Energy storage valve submodule and energy storage system

Abstract

The invention relates to an energy storage valve sub-module and an energy storage system, a resistance-inductance-capacitance damping circuit is arranged in parallel between a power conversion module and an energy storage module of the energy storage valve sub-module, and the resistance-inductance-capacitance damping circuit is connected in parallel with the energy storage module in the operation process of the energy storage valve sub-module. Under-damped oscillation between the power conversion module and the energy storage module can be restrained through the resistance-inductance-capacitance damping circuit, so that the situation that charging and discharging currents of the energy storage module exceed rated operation currents due to oscillation currents is relieved, abnormal attenuation of the service life of the energy storage module is reduced, and then the operation reliability of the energy storage valve sub-module is improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an energy storage valve submodule and an energy storage system. Background Art

[0002] Energy storage provides frequency regulation and peak regulation in all aspects of power generation, transmission, distribution and use, and plays a role in stabilizing the frequency of the power grid, alleviating grid congestion, and improving the flexibility of power generation and use. The cascade energy storage system has the advantages of modular design, high capacity utilization, high conversion efficiency, fast dynamic response, low harmonic content, and stable system operation. It has become a current research hotspot and has broad application prospects.

[0003] The energy storage valve submodule is the core component of the cascade energy storage system. By controlling the switching state of each energy storage valve submodule, the energy storage system completes the charging and discharging operation. However, in the related art, the operation reliability of the energy storage valve submodule is low. Summary of the invention

[0004] Based on this, it is necessary to provide an energy storage valve submodule and an energy storage system to improve the operational reliability of the energy storage valve submodule.

[0005] The present application provides an energy storage valve submodule, comprising a power conversion module, an energy storage module and a resistor, inductor and capacitor damping circuit, wherein the resistor, inductor and capacitor damping circuit are respectively arranged in parallel with the power conversion module and the energy storage module.

[0006] In the above scheme, a resistor, inductor, and capacitor damping circuit is arranged in parallel between the power conversion module and the energy storage module of the energy storage valve submodule. During the operation of the energy storage valve submodule, the resistor, inductor, and capacitor damping circuit can suppress the under-damped oscillation between the power conversion module and the energy storage module, thereby alleviating the situation in which the charging and discharging current of the energy storage module exceeds the rated operating current due to the oscillating current, reducing the abnormal attenuation of the life of the energy storage module, and thereby improving the operational reliability of the energy storage valve submodule.

[0007] In some embodiments, the RC damping circuit includes a first RC series branch, wherein the first RC series branch is connected in parallel with the power conversion module and the energy storage module;

[0008] The first resistor-inductor-capacitor series branch includes a first resistive element, a first inductive element and a first capacitive element, and the first resistive element, the first inductive element and the first capacitive element are arranged in series.

[0009] In the above scheme, the resistor, inductor and capacitor series branch includes a first resistive element, a first inductive element and a first capacitive element connected in series in sequence, that is, the resistor, inductor and capacitor series branch resonates in series to achieve suppression of under-damped oscillation, and has higher operating reliability.

[0010] In some embodiments, the first resistor-inductor-capacitor series branch further includes a first switch, and the first switch is arranged in parallel with the first resistive element.

[0011] In the above scheme, a first switch is also connected in parallel at both ends of the first resistive element of the first resistor-inductor-capacitor series branch. According to the on-off of the first switch, the energy storage valve submodule is precisely controlled to perform under-damped oscillation under the charging condition of the energy storage module, or to perform under-damped oscillation under the discharging condition, thereby achieving precise suppression of the under-damped oscillation.

[0012] In some embodiments, the first resistor-inductor-capacitor series branch further includes a second resistive element, a second switch and a third switch, the second switch is arranged in series between the first resistive element and the first inductive element, and after the second switch and the second resistive element are connected in series, they are arranged in parallel with the series branch of the first resistive element and the second switch.

[0013] In the above scheme, the first resistor-inductor-capacitor series branch is connected in series with the second switch between the first resistive element and the first inductive element. At the same time, a group of second resistive elements and third switches arranged in series are connected in parallel at both ends of the second switch and the first resistive element. When the energy storage module is in a charging condition and a discharging condition, different resistive elements can be connected to suppress under-damped oscillations, that is, under-damped oscillations are suppressed through different branches, thereby improving the suppression accuracy of under-damped oscillations.

[0014] In some embodiments, the RC damping circuit further includes a second RC series branch, and the second RC series branch is connected in parallel with the first RC series branch and the energy storage module;

[0015] The second resistor-inductor-capacitor series branch includes a third resistive element, a second inductive element and a second capacitive element, and the third resistive element, the second inductive element and the second capacitive element are arranged in series.

[0016] In the above scheme, the second resistor, inductor and capacitor series branch includes a third resistive element, a second inductive element and a second capacitive element connected in series in sequence, that is, a resistor, inductor and capacitor damping resonance in series, which can not only suppress under-damped oscillations, but also effectively reduce circuit volume and circuit cost.

[0017] In some embodiments, the second resistor-inductor-capacitor series branch further includes a fourth switch, and the fourth switch is connected in parallel with the third resistive element.

[0018] In the above scheme, a fourth switch is further connected in parallel at both ends of the third resistive element of the second resistor-inductor-capacitor series branch. According to the on-off of the fourth switch, the energy storage valve submodule is precisely controlled to perform under-damped oscillation under the charging condition of the energy storage module, or to perform under-damped oscillation under the discharging condition, thereby achieving precise suppression of the under-damped oscillation.

[0019] In some embodiments, the second resistor-inductor-capacitor series branch further includes a fourth resistive element, a fifth switch and a sixth switch, the fifth switch is arranged in series between the third resistive element and the second inductive element, and the sixth switch and the fourth resistive element are connected in series and then arranged in parallel with the series branch of the third resistive element and the fifth switch.

[0020] In the above scheme, the second resistor-inductor-capacitor series branch is connected in series with the fifth switch between the third resistive element and the second inductive element. At the same time, a group of fourth resistive elements and sixth switches arranged in series are connected in parallel at both ends of the fifth switch and the third resistive element. When the energy storage module is in a charging condition and a discharging condition, different resistive elements can be connected to suppress under-damped oscillations, that is, under-damped oscillations are suppressed through different branches, thereby improving the suppression accuracy of under-damped oscillations.

[0021] In some embodiments, the energy storage valve submodule includes at least one of the following items: first item: the resistance range of the first resistive element includes 1mΩ-1000mΩ; second item: the inductance range of the first inductive element includes 1uH-1000uH; third item: the capacitance range of the first capacitive element includes 1mF-1000mF.

[0022] In the above scheme, the resistance of the first resistive element is set to the milliohm level, the inductance of the first inductive element is set to the microhenry level, and the capacitance of the first capacitive element is set to the millifarad level, so as to meet the design requirements of flexible direct current engineering parameters and improve the operation reliability of the energy storage valve submodule.

[0023] In some embodiments, the energy storage valve submodule includes at least one of the following items: first item: the resistance range of the first resistive element includes 50mΩ-80mΩ; second item: the inductance range of the first inductive element includes 1uH-100uH; third item: the capacitance range of the first capacitive element includes 1mF-10mF.

[0024] In the above scheme, the resistance value of the first resistive element is selected from 50mΩ-80mΩ, the inductance value of the first inductive element is selected from 1uH-100uH, and the capacitance value of the first capacitive element is selected from 1mF-10mF. Under the condition of meeting the design requirements of the flexible direct current engineering parameters, the actual parameters of the resistance, inductance and capacitance damping circuit are matched with the oscillation condition of the energy storage valve submodule, which can effectively improve the oscillation suppression accuracy of the first resistance, inductance and capacitance series branch.

[0025] In some embodiments, the capacitance of the second capacitive element is smaller than the capacitance of the first capacitive element, and / or the inductance of the second inductive element is greater than the inductance of the first inductive element.

[0026] In the above scheme, based on the first resistor-inductor-capacitor series branch, in the resistor-inductor-capacitor series branch arranged in parallel, the capacitance of the second capacitive element is smaller than that of the first capacitive element, and / or the inductance of the second inductive element is greater than that of the first inductive element, thereby improving the reliability of the reduction of the current gain of the energy storage module in the frequency band lower than the resonant frequency.

[0027] In some embodiments, the power conversion module includes a power unit and a DC support capacitor, the first end of the DC support capacitor is connected to the first end of the resistor, inductor and capacitor damping circuit and the first DC end of the power unit, the second end of the DC support capacitor is connected to the second end of the resistor, inductor and capacitor damping circuit and the second DC end of the power unit, the first AC end and the second AC end of the power unit are used to cascade with other energy storage valve sub-modules, and the control end of the power unit is used to connect to a controller.

[0028] In the above scheme, the power conversion module includes a DC support capacitor and a power unit, which is connected to other energy storage valve submodules through the first AC end and the second AC end of the power unit, the first DC end and the second DC end are connected to the DC support capacitor, and the control end is connected to the controller. The overall circuit structure is simple, which can effectively reduce the circuit volume and circuit cost.

[0029] In some embodiments, the power conversion module further includes a bypass switch, and the first AC end and the second AC end of the power unit are respectively connected to the bypass switch.

[0030] In the above scheme, a bypass switch is also connected to the power unit. When the energy storage valve submodule fails, the power conversion module can be bypassed by the bypass switch, thereby effectively improving the operation safety of the energy storage valve submodule.

[0031] In some embodiments, the power cell comprises a full-bridge power cell or a half-bridge power cell.

[0032] In the above scheme, the power unit can be built into a full-bridge structure power unit or a half-bridge structure power unit according to actual conditions, so as to be suitable for different scenarios and improve the application scope of the energy storage valve submodule.

[0033] In some embodiments, the equivalent circuit of the energy storage valve submodule includes an equivalent inductance and an equivalent internal resistance of the energy storage module; and / or, the equivalent circuit of the energy storage valve submodule includes an equivalent inductance and an equivalent internal resistance of a busbar.

[0034] In the above scheme, the equivalent circuit of the energy storage valve submodule may include the equivalent inductance and equivalent internal resistance of the energy storage module. In the actual operation process, the resistor, inductor, and capacitor damping circuit can suppress the under-damped oscillation caused by the equivalent inductance and equivalent internal resistance of the energy storage module. It can also include the equivalent inductance and equivalent internal resistance of the busbar, and the resistor, inductor, and capacitor damping circuit can suppress the under-damped oscillation caused by the equivalent inductance and equivalent internal resistance of the busbar. The resistor, inductor, and capacitor damping circuit has good applicability.

[0035] The present application also provides an energy storage system, comprising the above-mentioned energy storage valve submodule. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 It is a schematic diagram of the topological structure of the energy storage valve submodule;

[0038] Figure 2 It is a schematic diagram of the equivalent network structure of the energy storage valve submodule;

[0039] Figure 3 This is a schematic diagram of the structure of the energy storage valve submodule in some embodiments of the present application;

[0040] Figure 4 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0041] Figure 5 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0042] Figure 6 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0043] Figure 7 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0044] Figure 8 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0045] Fig. 9 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0046] Fig.10 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0047] Fig.11 This is a schematic diagram of the structure of the energy storage valve submodule in some other embodiments of the present application;

[0048] Fig.12 The current transfer Bode diagram of the energy storage module in some embodiments of the present application;

[0049] Fig.13 A schematic diagram of a current waveform of an energy storage module in some embodiments of the present application;

[0050] Fig.14 The current transfer Bode diagram of the energy storage module in other embodiments of the present application;

[0051] Fig.15 Schematic diagram of current waveform of energy storage module in other embodiments of the present application. DETAILED DESCRIPTION

[0052] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians 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" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0054] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0055] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0056] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0057] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0058] At present, from the perspective of the development of the market situation, high-voltage direct-mounted energy storage has gradually been developed and applied because of its highly modular structure and ability to meet the needs of high efficiency, high reliability, economy and safety. In the high-voltage direct-mounted energy storage system, the core part is the energy storage valve submodule. Each energy storage valve submodule includes a power part and an energy storage part. Multiple energy storage valve submodules are connected to form an energy storage system. Typically, energy storage valve submodules are cascaded to form a cascade energy storage system. Therefore, the reliable operation of the energy storage valve submodule directly affects the operation of the energy storage system. How to improve the operational reliability of the energy storage valve submodule is particularly important.

[0059] During the operation of the energy storage valve submodule, if the DC support capacitor in the power conversion unit is not considered, due to the battery resistance-capacitance effect of the energy storage module under the charging and discharging operating conditions, combined with the equivalent inductance of the busbar or the equivalent inductance of the energy storage module itself, the equivalent circuit can be regarded as an RLC network, which will cause the energy storage valve submodule to produce under-damped oscillations during operation.

[0060] Furthermore, if the DC support capacitor in the power conversion unit is considered, the topology of the energy storage valve submodule is as follows: Figure 1 As shown, it can be equivalent to Figure 2The equivalent circuit shown in FIG. 1 is a circuit diagram of the power conversion module 101. The power conversion part in the power conversion module 101 can be regarded as an applied step trigger signal, C represents the DC support capacitor of the power conversion module 101, L represents the equivalent inductance of the energy storage module 103 and / or the equivalent inductance of the busbar in the energy storage valve submodule, R represents the internal resistance of the energy storage module 103 and / or the internal resistance of the busbar, I represents the internal resistance of the energy storage module 103 and / or the internal resistance of the busbar, and L (S) and I S (s) respectively represent the current of the energy storage module 103 and the power conversion module 101. As can be seen from the figure, the equivalent topology of the energy storage valve submodule can be regarded as an RLC network.

[0061] During the operation of the energy storage valve submodule, when the switching between the input and cut-off working modes is executed, the DC support capacitor, equivalent internal resistance and equivalent inductance of the power conversion module 101 will cause underdamped oscillation. The energy storage module 103 will have an oscillating current, causing the charging and discharging currents to exceed the rated operating current, which can easily cause abnormal attenuation of the service life of the energy storage module 103 and reduce the operational reliability of the energy storage valve submodule.

[0062] In order to alleviate the problem of low operating reliability of the energy storage valve submodule caused by the above-mentioned under-damped oscillation, the structure of the energy storage valve submodule can be improved, and an oscillation suppression circuit can be added to the energy storage valve submodule to reduce the current gain of the energy storage module 103 when the energy storage valve submodule switches between the input and cut-off working modes, thereby suppressing the under-damped oscillation caused by the internal resistive elements and integrated inductive elements between the DC support capacitor and the energy storage module 103, thereby improving the operating reliability of the energy storage valve submodule.

[0063] Based on the above considerations, in the technical solution of the present application, a resistor-inductor-capacitor damping circuit is arranged in parallel on the side of the DC support capacitor of the power conversion module 101 close to the energy storage module 103, that is, a circuit including a resistive element R, an inductive element L and a capacitive element C, which can also be called an RLC damping circuit. In this way, the current gain of the energy storage module 103 can be reduced during the process of the energy storage valve submodule performing the switching of the input and cut-off working modes, thereby alleviating the influence of the oscillating current on the energy storage module 103 and improving the operating reliability of the energy storage module 103.

[0064] Furthermore, in order to make the oscillation suppression degree or effect of the RC damping circuit match that of the energy storage valve sub-module, it is also possible to configure corresponding device parameters for each component in the RC damping circuit in combination with relevant parameters of the energy storage valve sub-module in actual application scenarios, such as resonant frequency, damping ratio and gain coefficient, so as to improve the accuracy of oscillation suppression.

[0065] It can be understood that in the resistor-inductor-capacitor damping circuit, the specific types of resistive elements, inductive elements and capacitive elements are not unique. In one embodiment, the resistive element includes a resistor, the inductive element includes an inductor, and the capacitive element includes a capacitor. More specifically, in one embodiment, the resistive element may include a resistor, or a resistor component formed by connecting two or more resistors in series and / or in parallel, which is not specifically limited. The inductive element may include an inductor, or an inductor component formed by connecting two or more inductors in series and / or in parallel, which is not specifically limited. The capacitive element may include a capacitor, or a capacitor component formed by connecting two or more capacitors in series and / or in parallel, which is not specifically limited.

[0066] The energy storage valve submodule provided in the present application is applied in an energy storage system. Specifically, the energy storage valve submodule is applied in an electrochemical energy storage system, that is, an energy storage system that stores, releases and manages energy through batteries. Furthermore, the type of electrochemical energy storage system is not unique, as long as it is an electrochemical energy storage system that needs to be built using an energy storage valve submodule. For example, in a more detailed embodiment, the electrochemical energy storage system includes a high-voltage direct-mounted energy storage system. In order to facilitate understanding of the technical solution of the present application, the following embodiments can all be understood as the energy storage valve submodule being applied in a high-voltage direct-mounted energy storage system.

[0067] See also Figure 3 A storage valve submodule includes a power conversion module 101, an energy storage module 103 and a resistor-inductor-capacitor damping circuit 301, wherein the resistor-inductor-capacitor damping circuit 301 is respectively connected in parallel with the power conversion module 101 and the energy storage module 103.

[0068] Specifically, the power conversion module 101 is a device in the energy storage valve submodule for realizing the power conversion function, which at least includes two parts: power conversion and DC support capacitor. The energy storage module 103 is a device in the energy storage valve submodule for realizing electric energy storage. During the operation of the energy storage valve submodule, the energy storage module 103 can store or release electric energy according to actual needs. The resistance, inductance and capacitance damping circuit 301 is a circuit formed by resistive elements, inductive elements and capacitors, and has the function of suppressing under-damped oscillations, that is, an RLC damping circuit.

[0069] In the solution of this embodiment, the resistor, inductor, and capacitor damping circuit 301 is set in parallel with the power conversion module 101 and is located between the power conversion module 101 and the energy storage module 103. During the operation of the energy storage valve submodule, the resistor, inductor, and capacitor damping circuit 301 can reduce the current gain of the energy storage module 103, thereby alleviating the impact of the oscillating current on the energy storage module 103.

[0070] In such Figure 2In the equivalent network shown in FIG. 1 , taking the equivalent inductance and equivalent internal resistance of the energy storage module 103 and the busbar as an example, the inherent oscillation frequency of the energy storage valve submodule can be expressed as Wherein, R represents the equivalent internal resistance of the energy storage module 103 and the busbar, L represents the equivalent inductance of the energy storage module 103 and the busbar, C represents the DC support capacitance of the power conversion module 101, and s represents a complex variable.

[0071] The current transfer function of the energy storage module 103 can be expressed as: Among them, I L (s) represents the current of the energy storage module 103, I S (s) represents the current of the power conversion module 101. Further, in combination with the equivalent inductance of the energy storage module 103 and the busbar, and the equivalent internal resistance of the energy storage module 103 and the busbar in the equivalent network, the current transfer function can be equivalent to:

[0072] After the parallel resistor, inductor and capacitor damping circuit 301, the equivalent network of the energy storage valve submodule is as follows: Figure 3 As shown, correspondingly, in this state, the current transfer function of the energy storage module 103 is: Among them, Y s Represents the admittance of the RC damping circuit 301. Figure 2 In the equivalent network shown in FIG. 1 , the current transfer function of the energy storage module 103 has Y added to the denominator. s , the energy storage valve submodule after the parallel resistor, inductor and capacitor damping circuit 301 can have a lower current gain than the energy storage valve submodule without the parallel resistor, inductor and capacitor damping circuit 301, thereby being able to suppress under-damped oscillation.

[0073] In the above scheme, a resistor, inductor, and capacitor damping circuit 301 is arranged in parallel between the power conversion module 101 and the energy storage module 103 of the energy storage valve submodule. During the operation of the energy storage valve submodule, the resistor, inductor, and capacitor damping circuit 301 can suppress the under-damped oscillation between the power conversion module 101 and the energy storage module 103, thereby alleviating the situation in which the charging and discharging current of the energy storage module 103 exceeds the rated operating current due to the oscillating current, reducing the abnormal attenuation of the life of the energy storage module 103, and thereby improving the operational reliability of the energy storage valve submodule.

[0074] See also Figure 4 In some embodiments, the RC damping circuit 301 includes a first RC series branch 501 , and the first RC series branch 501 is connected in parallel with the power conversion module 101 and the energy storage module 103 .

[0075] Specifically, in the solution of this embodiment, the resistor, inductor, and capacitor damping circuit 301 specifically includes a resistor, inductor, and capacitor series branch, that is, includes a first resistor, inductor, and capacitor series branch 501, which is arranged in parallel between the power conversion module 101 and the energy storage module 103. The resistor, inductor, and capacitor series branch is used to reduce the current gain of the energy storage module 103 in the energy storage valve submodule, thereby achieving the suppression of under-damped oscillations.

[0076] In the above scheme, the resistor, inductor and capacitor damping circuit 301 specifically includes a resistor, inductor and capacitor series branch, that is, a resistor, inductor and capacitor series branch is connected in parallel on the side of the power conversion module 101 close to the energy storage module 103, which can effectively reduce the circuit volume while achieving reliable suppression of under-damping.

[0077] It should be noted that the specific structure of the first resistor, inductor and capacitor series branch 501 is not unique. Figure 4 In some more detailed embodiments, the first resistor-inductor-capacitor series branch 501 includes a resistor-inductor-capacitor series resonant circuit, that is, the first resistor-inductor-capacitor series branch 501 includes a first resistive element R1, a first inductive element L1 and a first capacitive element C1. After the first resistive element R1, the first inductive element L1 and the first capacitive element C1 are connected in series, they are arranged in parallel with the power conversion module 101 and the energy storage module 103.

[0078] More specifically, in one embodiment, a first end of the first resistive element R1 is connected to a first end of the power conversion module 101 and a first end of the energy storage module 103, a second end of the first resistive element R1 is connected to a first end of the first inductive element L1, a second end of the first inductive element L1 is connected to a first end of the first capacitive element C1, and a second end of the first capacitive element C1 is connected to a second end of the power conversion module 101 and a second end of the energy storage module 103.

[0079] Specifically, in the solution of this embodiment, the first resistive element R1, the first inductive element L1 and the first capacitive element C1 are connected in series in sequence, the first end of the first resistive element R1 is used as the first end of the first resistor, inductor and capacitor series branch 501, the second end of the first capacitive element C1 is used as the second end of the first resistor, inductor and capacitor series branch 501, and the series resistor, inductor and capacitor series branches are connected in parallel between the power conversion module 101 and the energy storage module 103. When the energy storage valve submodule operates in the charging mode or the discharging mode, under-damped oscillation suppression can be achieved through the same resistor, inductor and capacitor series branch.

[0080] It should be noted that, in one embodiment, the first end of the energy storage module 103 may be the positive electrode of the energy storage module 103, and the second end of the energy storage module 103 may be the negative electrode. In another embodiment, the first end of the energy storage module 103 may be the negative electrode, and the second end of the energy storage module 103 may be the positive electrode. There is no specific limitation, and the selection may be made in combination with actual needs.

[0081] The admittance of the RC damping circuit 301 can be expressed as: Wherein, R1 represents the resistance value of the first resistive element R1, L1 represents the inductive element value of the first inductive element L1, C1 represents the capacitance value of the first capacitive element C1, and s represents a complex variable. The above formula is transformed, and the numerator and denominator are multiplied by Then we get:

[0082]

[0083] The second-order bandpass filter has the characteristics of precise filtering, fast attenuation, and phase retention. Its transfer function is: Where K is the gain coefficient, ξ is the damping ratio, ω n is the center frequency (resonant frequency). The series branch of resistance, inductance and capacitance can be used as an electronic harmonic oscillator, a bandpass or bandstop filter in practical applications. Therefore, the above Y(s) is compared to a second-order bandpass filter to obtain: and

[0084] Therefore, in actual application scenarios, the gain coefficient, damping ratio and resonant frequency of the energy storage valve submodule can be combined to realize the device parameter setting of the first resistor, inductor and capacitor series branch 501, and finally the constructed first resistor, inductor and capacitor series branch 501 is matched with the current energy storage valve submodule, and the current gain of the energy storage module 103 is reduced, thereby reducing the oscillation current and realizing accurate suppression of under-damped oscillation.

[0085] In a more detailed embodiment, in order to achieve under-damped oscillation suppression, the current gain of the current transfer function of the energy storage module 103 at the resonant frequency needs to be designed to be less than zero. Based on this idea, the gain coefficient is in the range of 10-100, and the damping ratio is in the range of 0.5-5. Combined with the resonant frequency of the energy storage valve submodule in the actual scenario, the above mapping relationship is substituted, and the power upper limit of the resistive element is combined at the resonant frequency for precise design. Finally, the capacitance value of the first capacitive element C1 is in the mF level, the inductive element value of the first inductive element L1 is in the μH level, and the resistive element value of the first resistive element R1 is in the mΩ level, so as to meet the design requirements of the flexible direct current engineering parameters.

[0086] In the above scheme, the resistor, inductor and capacitor series branch includes a first resistive element R1, a first inductive element L1 and a capacitor connected in series in sequence, that is, the resistor, inductor and capacitor series branch resonates in series to achieve suppression of under-damped oscillation, and has higher operating reliability.

[0087] See also Figure 5 In some embodiments, the first RC series branch 501 further includes a first switch D1, and the first switch D1 is connected in parallel with the first resistive element R1.

[0088] It can be understood that the specific type of the first switch D1 is not unique, as long as the first resistive element R1 is short-circuited when the energy storage valve submodule is in the charging state, or the first resistive element R1 is short-circuited when the energy storage valve submodule is in the discharging state. For example, the first switch D1 can be a semiconductor switch device, whose control end is connected to the controller, and the on-off control is realized under the control of the controller. In another embodiment, the first switch D1 can also be a diode.

[0089] For ease of understanding, the first switch D1 including a diode is taken as an example for explanation. In more detail, at this time, the cathode of the first switch D1 is connected to the first end of the first resistive element R1, and the anode of the first switch D1 is connected to the second end of the first resistive element R1.

[0090] Specifically, the first resistor-inductor-capacitor series branch 501 is also provided with a first switch D1 in parallel at both ends of the first resistive element R1, so that the first resistor-inductor-capacitor series branch 501 suppresses the oscillation of the energy storage valve submodule under the charging condition, or suppresses the oscillation of the energy storage valve submodule under the discharging state. Specifically, if the first end of the energy storage module 103 is the positive pole and the second end of the energy storage module 103 is the negative pole, under the charging condition, the current is transmitted through the first resistive element R1, the first inductive element L1 and the first capacitive element C1, and oscillation suppression can be achieved at this time; while under the discharging condition, the current is transmitted through the first capacitive element C1, the first inductive element L1 and the first switch D1, and no oscillation suppression is performed at this time. On the contrary, if the second end of the energy storage module 103 is the positive pole and the first end of the energy storage module 103 is the negative pole, oscillation suppression is performed under the discharging condition, and oscillation suppression is not performed under the charging condition.

[0091] In the above scheme, a first switch D1 is further connected in parallel at both ends of the first resistive element R1 of the first resistor-inductor-capacitor series branch 501. According to the on-off of the first switch D1, the energy storage valve submodule is precisely controlled to perform under-damped oscillation under the charging condition of the energy storage module 103, or to perform under-damped oscillation under the discharging condition, thereby achieving precise suppression of the under-damped oscillation.

[0092] See also Figure 6In some embodiments, the first resistor-inductor-capacitor series branch 501 further includes a second resistive element R2, a second switch D2, and a third switch D3. The second switch D2 is arranged in series between the first resistive element R1 and the first inductive element L1. After the third switch D3 and the second resistive element R2 are connected in series, they are arranged in parallel with the series branch of the first resistive element R1 and the second switch D2.

[0093] More specifically, in one embodiment, the second switch D2 and the third switch D3 both include diodes, the second end of the first resistive element R1 is connected to the anode of the second switch D2, the cathode of the second switch D2 is connected to the first end of the second resistive element R2 and the first end of the first inductive element L1, the second end of the second resistive element R2 is connected to the anode of the third switch D3, and the cathode of the third switch D3 is connected to the first end of the first resistive element R1.

[0094] Specifically, the solution of this embodiment utilizes the on-off characteristics of the switch to set two different circuits in the first resistor-inductor-capacitor series branch 501, and respectively set a first resistive element R1 and a second resistive element R2 to suppress oscillations under charging conditions and discharging conditions, thereby improving the reliability of oscillation suppression under charging conditions and discharging conditions.

[0095] Specifically, if the first end of the energy storage module 103 is a positive electrode and the second end of the energy storage module 103 is a negative electrode, under the charging condition, the current is transmitted through the first resistive element R1, the second switch D2, the first inductive element L1 and the first capacitive element C1 to achieve oscillation suppression; and under the discharging condition, the current is transmitted through the first capacitive element C1, the first inductive element L1, the second resistive element R2 and the third switch D3 to achieve oscillation suppression. On the contrary, if the second end of the energy storage module 103 is a positive electrode and the first end of the energy storage module 103 is a negative electrode, under the discharging condition, the current is transmitted through the first resistive element R1, the second switch D2, the first inductive element L1 and the first capacitive element C1 to achieve oscillation suppression; and under the charging condition, the current is transmitted through the first capacitive element C1, the first inductive element L1, the second resistive element R2 and the third switch D3 to achieve oscillation suppression.

[0096] It can be understood that the resistance values ​​of the first resistive element R1 and the second resistive element R2 are not unique, and can be set in combination with the charging condition and the discharging condition of the energy storage valve. In one embodiment, the resistance values ​​of the first resistive element R1 and the second resistive element R2 can be set to be different. In another embodiment, the resistance values ​​of the first resistive element R1 and the second resistive element R2 can also be set to be the same.

[0097] In the above scheme, the first resistor-inductor-capacitor series branch 501 is connected in series with the second switch D2 between the first resistive element R1 and the first inductive element L1, and at the same time, a second resistive element R2 and a third switch D3 that are arranged in series in reverse are connected in parallel at both ends of the second switch D2 and the first resistive element R1. When the energy storage module 103 is in a charging condition and a discharging condition, different resistive elements can be connected to suppress under-damped oscillations, that is, under-damped oscillations are suppressed through different branches, thereby improving the suppression accuracy of under-damped oscillations.

[0098] See also Figure 7 In some embodiments, the RC damping circuit 301 further includes a second RC series branch 801 , and the second RC series branch 801 is connected in parallel with the first RC series branch 501 and the energy storage module 103 .

[0099] Specifically, in the solution of this embodiment, the resistor, inductor, and capacitor damping circuit 301 includes a first resistor, inductor, and capacitor series branch 501 and a second resistor, inductor, and capacitor series branch 801. The first resistor, inductor, and capacitor series branch 501 and the second resistor, inductor, and capacitor series branch 801 are connected in parallel to form a resistor, inductor, and capacitor damping circuit 301. Then, the resistor, inductor, and capacitor damping circuit 301 is arranged in parallel between the power conversion module 101 and the energy storage module 103, and the oscillation suppression of the energy storage valve submodule is achieved through the two resistor, inductor, and capacitor series branches.

[0100] In the above scheme, the resistor-inductor-capacitor damping circuit 301 includes a first resistor-inductor-capacitor series branch 501 and a second resistor-inductor-capacitor series branch 801 connected in parallel. Through the design of the two resistor-inductor-capacitor series branches, the current gain of the energy storage module 103 in the frequency band lower than the resonant frequency can be effectively reduced, and the suppression reliability of under-damped oscillation can be further improved.

[0101] Please continue reading Figure 7 In some embodiments, the second resistor-inductor-capacitor series branch 801 includes a third resistive element R3, a second inductive element L2, and a second capacitive element C2. After the third resistive element R3, the second inductive element L2, and the second capacitive element R2 are connected in series, they are arranged in parallel with the first resistor-inductor-capacitor series branch 501 and the energy storage module 103.

[0102] In more detail, in one embodiment, a first end of the third resistive element R3 is connected to a first end of the energy storage module 103 and a first end of the first resistor-inductor-capacitor series branch 501, a second end of the third resistive element R3 is connected to a first end of the second inductive element L2, a second end of the second inductive element L2 is connected to a first end of the second capacitive element C2, and a second end of the second capacitive element C2 is connected to a second end of the first resistor-inductor-capacitor series branch 501 and the energy storage module 103.

[0103] Specifically, the third resistive element R3, the second inductive element L2 and the second capacitive element C2 are connected in series in sequence, and the first end of the third resistive element R3 is used as the first end of the second resistor, inductor and capacitor series branch 801, and the second end of the second capacitive element C2 is used as the second end of the second resistor, inductor and capacitor series branch 801. The first ends of the first resistor, inductor and capacitor series branch 501 and the second resistor, inductor and capacitor series branch 801 are used together as the first end of the resistor, inductor and capacitor damping circuit 301, and the second ends of the first resistor, inductor and capacitor series branch 501 and the second resistor, inductor and capacitor series branch 801 are used together as the second end of the resistor, inductor and capacitor damping circuit 301, and are connected in parallel between the power conversion module 101 and the energy storage module 103. When the energy storage valve submodule operates in the charging mode or the discharging mode, the under-damped oscillation suppression can be achieved through the first resistor, inductor and capacitor series branch 501 and the second resistor, inductor and capacitor series branch 801.

[0104] Accordingly, in the solution of this embodiment, the admittance of the RC damping circuit 301 can be expressed as: Wherein, R1 represents the resistance value of the first resistive element R1, L1 represents the inductive element value of the first inductive element L1, C1 represents the capacitance value of the first capacitive element C1, s represents a complex variable, R3 represents the resistance value of the third resistive element R3, L2 represents the inductive element value of the second inductive element L2, and C2 represents the capacitance value of the second capacitive element C2. According to a method similar to the first RC series branch 501 described above, the resistance value of the third resistive element R3, the inductive element value of the second inductive element L2, and the capacitance value of the second capacitive element C2 are appropriately selected to finally achieve oscillation suppression.

[0105] It should be pointed out that in the solution of this embodiment, relative to the first resistor, inductor and capacitor series branch 501 designed in the above embodiment, if the selected resonant frequency is relatively small, it is necessary to appropriately reduce the capacitance value of the second capacitive element C2 of the second resistor, inductor and capacitor series branch 801 and / or increase the inductive element value of the second inductive element L2 on the basis of the device parameters of the first resistor, inductor and capacitor series branch 501, so as to reduce the current gain in the frequency band below the resonant frequency.

[0106] It can be understood that in the solution of this embodiment, the structure of the first resistor, inductor and capacitor series branch 501 is not unique. The specific structure of the first resistor, inductor and capacitor series branch 501 can refer to the above embodiments and drawings. It can include a first resistive element R1, a first inductive element L1 and a first capacitive element C1, or it can include a first resistive element R1, a first inductive element L1, a first capacitive element C1 and a first switch D1, or it can include a first resistive element R1, a first inductive element L1, a first capacitive element C1, a second resistive element R2, a second switch D2 and a third switch D3. It only needs to be selected according to actual needs.

[0107] In more detail, in one embodiment, the first resistor-inductor-capacitor series branch 501 has the same structure as the second resistor-inductor-capacitor series branch 801, including a first resistive element R1, a first inductive element L1 and a first capacitive element C1. Through the solution of this embodiment, through two resistor-inductor-capacitor series branches, oscillation suppression under charging conditions and oscillation suppression under discharging conditions can be achieved.

[0108] In the above scheme, the second resistor-inductor-capacitor series branch 801 includes a third resistive element R3, a second inductive element L2 and a second capacitive element C2 connected in series in sequence, that is, the resistor-inductor-capacitor series branch resonates in series, which can not only suppress under-damped oscillations, but also effectively reduce circuit volume and circuit cost.

[0109] See also Figure 8 In some embodiments, the second RC series branch 801 further includes a fourth switch D4, and the fourth switch D4 is connected in parallel with the third resistive element R3.

[0110] More specifically, in one embodiment, the fourth switch D4 includes a diode, a cathode of the fourth switch D4 is connected to the first end of the third resistive element R3, and an anode of the fourth switch D4 is connected to the second end of the third resistive element R3.

[0111] Specifically, in the solution of this embodiment, the second resistor-inductor-capacitor series branch 801 is provided with a fourth switch D4 in parallel at both ends of the third resistive element R3, and by utilizing the on-off characteristics of the fourth switch D4, the second resistor-inductor-capacitor series branch 801 can conduct the oscillation suppression circuit under the charging condition, and not conduct the oscillation suppression under the discharging condition. Alternatively, the oscillation suppression circuit is conducted under the discharging condition, and not conduct the oscillation suppression under the charging condition.

[0112] It can be understood that in the solution of this embodiment, the structure of the first resistor, inductor and capacitor series branch 501 is not unique. The specific structure of the first resistor, inductor and capacitor series branch 501 can refer to the above embodiments and drawings. It can include a first resistive element R1, a first inductive element L1 and a first capacitive element C1, or it can include a first resistive element R1, a first inductive element L1, a first capacitive element C1 and a first switch D1, or it can include a first resistive element R1, a first inductive element L1, a first capacitive element C1, a second resistive element R2, a second switch D2 and a third switch D3. It only needs to be selected according to actual needs.

[0113] In more detail, in one embodiment, the structure of the first resistor-inductor-capacitor series branch 501 is similar to the structure of the second resistor-inductor-capacitor series branch 801, and the first resistor-inductor-capacitor series branch 501 includes a first resistive element R1, a first inductive element L1, a first capacitive element C1 and a first switch D1. Taking the first end of the energy storage module 103 as the positive electrode and the second end as the negative electrode as an example, under the charging condition, the current is transmitted through the first resistive element R1, the first switch D1, the first inductive element L1, the first capacitive element C1, and the third resistive element R3, the fourth switch D4, the second inductive element L2 and the second capacitive element C2, and the oscillation suppression under the charging condition is realized by the dual oscillation suppression circuit, and under the discharging condition, the first resistive element R1 and the third resistive element R3 are short-circuited by the first switch D1 and the fourth switch D4 respectively, and the oscillation suppression cannot be realized at this time. Through this solution, accurate oscillation suppression under the charging condition or the discharging condition can be realized.

[0114] In the above scheme, a fourth switch D4 is further connected in parallel at both ends of the third resistive element R3 of the second resistor-inductor-capacitor series branch 801. According to the on-off characteristics of the fourth switch D4, the energy storage valve submodule is precisely controlled to perform under-damped oscillation under the charging condition of the energy storage module 103, or to perform under-damped oscillation under the discharging condition, thereby achieving precise suppression of the under-damped oscillation.

[0115] See also Fig. 9 In some embodiments, the second resistor-inductor-capacitor series branch 801 further includes a fourth resistive element R4, a fifth switch D5 and a sixth switch D6. The fifth switch D5 is arranged in series between the third resistive element R3 and the second inductive element L2. After the sixth switch D6 and the fourth resistive element R4 are connected in series, they are arranged in parallel with the series branch of the third resistive element R3 and the fifth switch D5.

[0116] In more detail, in one embodiment, the fifth switch D5 and the sixth switch D6 both include diodes, the second end of the third resistive element R3 is connected to the anode of the fifth switch D5, the cathode of the fifth switch D5 is connected to the first end of the second inductive element L2 and the first end of the fourth resistive element R4, the second end of the fourth resistive element R4 is connected to the anode of the sixth switch D6, and the cathode of the sixth switch D6 is connected to the first end of the third resistive element R3.

[0117] Specifically, the solution of this embodiment utilizes the on-off characteristics of the switch to set two different lines in the second resistor-inductor-capacitor series branch 801, and respectively set the third resistive element R3 and the fourth resistive element R4 to suppress oscillation in the charging condition and the discharging condition. Specifically, taking the first end of the energy storage module 103 as the positive electrode and the second end of the energy storage module 103 as the negative electrode as an example, under the charging condition, the current is transmitted through the third resistive element R3, the fifth switch D5, the second inductive element L2 and the second capacitive element C2 to achieve oscillation suppression; and under the discharging condition, the current is transmitted through the second capacitive element C2, the second inductive element L2, the fourth resistive element R4 and the sixth switch D6 to achieve oscillation suppression.

[0118] It should be noted that the resistance setting of the third resistive element R3 and the fourth resistive element R4 is not unique, and can be set specifically in combination with the charging condition and the discharging condition of the energy storage valve. In one embodiment, the resistance values ​​of the third resistive element R3 and the fourth resistive element R4 can be set to be different. In another embodiment, the resistance values ​​of the third resistive element R3 and the fourth resistive element R4 can also be set to be the same.

[0119] It can be understood that in the solution of this embodiment, the structure of the first resistor, inductor and capacitor series branch 501 is not unique. The specific structure of the first resistor, inductor and capacitor series branch 501 can refer to the above embodiments and drawings. It can include a first resistive element R1, a first inductive element L1 and a first capacitive element C1, or it can include a first resistive element R1, a first inductive element L1, a first capacitive element C1 and a first switch D1, or it can include a first resistive element R1, a first inductive element L1, a first capacitive element C1, a second resistive element R2, a second switch D2 and a third switch D3. The specific structure can be selected according to actual needs.

[0120] In more detail, in one embodiment, the structure of the first resistor, inductor, and capacitor series branch 501 is similar to the structure of the second resistor, inductor, and capacitor series branch 801, and includes a first resistive element R1, a first inductive element L1, a first capacitive element C1, a second resistive element R2, a second switch D2, and a third switch D3, thereby constructing an energy storage valve submodule. Under charging conditions and discharging conditions, the first resistor, inductor, and capacitor series branch 501 and the second resistor, inductor, and capacitor series branch 801 can be respectively connected with different oscillation circuits, and finally under-damped oscillation suppression is achieved through two oscillation circuits.

[0121] In the above scheme, the second resistor-inductor-capacitor series branch 801 is connected in series with the fifth switch D5 between the third resistive element R3 and the second inductive element L2. At the same time, a fourth resistive element R4 and a sixth switch D6 that are arranged in series in reverse are connected in parallel at both ends of the fifth switch D5 and the third resistive element R3. When the energy storage module 103 is in a charging condition and a discharging condition, different resistive elements can be connected to suppress under-damped oscillations, that is, under-damped oscillations are suppressed through different branches, thereby improving the suppression accuracy of under-damped oscillations.

[0122] In some embodiments, the resistance value of the first resistive element R1 ranges from 1 mΩ (milliohm) to 1000 mΩ. That is, the resistance value of the first resistive element R1 is set to the milliohm level, which can be 1 mΩ, 1000 mΩ, or any value between 1 mΩ and 1000 mΩ, for example, 100 mΩ, 200 mΩ, 300 mΩ, etc.

[0123] In some embodiments, the inductance value range of the first inductive element L1 includes 1uH (microhenry)-100uH. That is, the inductance value of the first inductive element L1 is set to the microhenry level, which can be 1uH, 1000uH, or any value between 1uH-1000uH, for example, 200uH, 4000uH, 600uH, etc.

[0124] In some embodiments, the capacitance value range of the first capacitive element C1 includes 1mF (millifarad)-1000mF. That is, the capacitance value of the first capacitive element C1 is set to the millifarad level, which can be 1mF, 1000mF, or any value between 1mF-1000mF, for example, 300mF, 500mF, 700mF, etc.

[0125] In the above embodiment, the resistance of the first resistive element R1 is set to the milliohm level, the inductance of the first inductive element L1 is set to the microhenry level, and the capacitance of the first capacitive element C1 is set to the millifarad level to meet the design requirements of flexible direct current engineering parameters and improve the operating reliability of the energy storage valve submodule.

[0126] More specifically, in some embodiments, the resistance value of the first resistive element R1 ranges from 50 mΩ to 80 mΩ, that is, the first resistive element R1 can be 50 mΩ, 80 mΩ, or any value between 50 mΩ and 80 mΩ, such as 60 mΩ, 70 mΩ, etc.

[0127] In some embodiments, the inductance value range of the first inductive element L1 includes 1uH-100uH. That is, the first inductive element L1 can be 1uH, 100uH, or any value between 1uH-100uH, for example, 10uH, 50uH, 90uH, etc.

[0128] In some embodiments, the capacitance range of the first capacitive element C1 includes 1 mF-10 mF, that is, the first capacitive element C1 can be 1 mF, 10 mF, or any value between 1 mF and 10 mF, for example, 3 mF, 5 mF, 7 mF, etc.

[0129] In the above scheme, the resistance value of the first resistive element R1 is selected from 50mΩ-80mΩ, the inductance value of the first inductive element L1 is selected from 1uH-100uH, and the capacitance value of the first capacitive element C1 is selected from 1mF-10mF. Under the condition of meeting the design requirements of flexible direct current engineering parameters, the actual parameters of the resistance, inductance and capacitance damping circuit are selected to match the oscillation working condition of the energy storage valve submodule, which can effectively improve the oscillation suppression accuracy of the first resistance, inductance and capacitance series branch 501.

[0130] It should be pointed out that in some embodiments, if the resonant frequency is selected to be relatively small relative to the first resistor, inductor, and capacitor series branch 501, it is necessary to appropriately reduce the capacitance value of the second capacitive element C2 of the second resistor, inductor, and capacitor series branch 801 and / or increase the inductive element value of the second inductive element L2 on the basis of the device parameters of the first resistor, inductor, and capacitor series branch 501, so as to improve the reliability of the reduction of the current gain in the frequency band below the resonant frequency.

[0131] See also Fig.10 In some embodiments, the power conversion module 101 includes a power unit 111 and a DC support capacitor C, a first end of the DC support capacitor C is connected to a first end of the resistor, inductor and capacitor damping circuit 301 and a first DC end of the power unit 111, a second end of the DC support capacitor C is connected to a second end of the resistor, inductor and capacitor damping circuit 301 and a second DC end of the power unit 111, a first AC end and a second AC end of the power unit 111 are used to be cascaded with other energy storage valve sub-modules, and a control end of the power unit 111 is used to connect to a controller (not shown).

[0132] Specifically, the power unit 111 is a device for realizing the power conversion function, which is specifically constructed by power switch devices in combination with actual needs. The DC support capacitor C is a capacitor for realizing DC power storage during the charging and discharging process of the energy storage module 103. The controller is a device in the energy storage valve submodule used to control the switching of the power conversion module 101.

[0133] In the above scheme, the power conversion module 101 includes a DC support capacitor C and a power unit 111, and other energy storage valve submodules are connected through the first AC end and the second AC end of the power unit 111, the first DC end and the second DC end are connected to the DC support capacitor C, and the control end is connected to the controller. The overall circuit structure is simple, which can effectively reduce the circuit volume and circuit cost.

[0134] See also Fig.10 In some embodiments, the power conversion module 101 further includes a bypass switch P, and the first AC end and the second AC end of the power unit 111 are connected to the bypass switch P respectively.

[0135] Specifically, the bypass switch P is a switch device connected across different power switch devices of the power unit 111. When the energy storage valve submodule fails, the bypass switch P is turned on to short-circuit the power unit 111, thereby cutting off the power unit 111.

[0136] In the above solution, a bypass switch P is also connected to the power unit 111. When the energy storage valve submodule fails, the power conversion module 101 can be bypassed by the bypass switch P, thereby effectively improving the operation safety of the energy storage valve submodule.

[0137] In some embodiments, the power cell 111 includes a full-bridge power cell or a half-bridge power cell.

[0138] For more details, see Fig.10 The half-bridge power unit includes a first power switch device T1 and a second power switch device T2, the input end of the first power switch device T1 is connected to the first end of the DC support capacitor C, the output end of the first power switch device T1 is connected to other energy storage valve sub-modules (not shown) and the input end of the second power switch device T2, the output end of the second power switch device T2 is connected to other energy storage valve sub-modules and the second end of the DC support capacitor C, and the control ends of the first power switch device T1 and the second power switch device T2 are respectively connected to the controller (not shown).

[0139] In some embodiments, see Fig.11The full-bridge power unit includes a third power switch device T3, a fourth power switch device T4, a fifth power switch device T5 and a sixth power switch device T6, the input end of the third power switch device T3 is connected to the input end of the fourth power switch device T4 and the first end of the DC support capacitor C, the output end of the third power switch device T3 is connected to other energy storage valve sub-modules (not shown) and the input end of the fifth power switch device T5, the output end of the fifth power switch device T5 is connected to the output end of the sixth power switch device T6 and the second end of the DC support capacitor C, the output end of the fourth power switch device T4 is connected to the input end of the sixth power switch device T6 and other energy storage valve sub-modules, and the control ends of the third power switch device T3, the fourth power switch device T4, the fifth power switch device T5 and the sixth power switch device T6 are respectively connected to the controller (not shown).

[0140] Specifically, the power unit 111 can be built in the form of a full bridge or a half bridge. In the half bridge structure, the input end of the first power switch device T1 is used as the first DC end, and the output end of the second power switch device T2 is used as the second DC end, which are respectively connected to the first end and the second end of the DC support capacitor C. The common connection end of the first power switch device T1 and the second power switch device T2 is used as the first AC end, and the output end of the second power switch device T2 is used as the second AC end for connecting other energy storage valve submodules. The control end of the first power switch device T1 and the control end of the second power switch device T2 are used as the control end of the power unit 111, which are connected to the controller, and then the switching conversion is realized under the control of the controller.

[0141] In the full-bridge structure, the common connection terminal of the third power switch device T3 and the fourth power switch device T4 is used as the first DC terminal, the common connection terminal of the fifth power switch device T5 and the sixth power switch device T6 is used as the second DC terminal, the common connection terminal of the third power switch device T3 and the fifth power switch device T5 is used as the first AC terminal, the common connection terminal of the fourth power switch device T4 and the sixth power switch device T6 is used as the second AC terminal, the control terminal of the third power switch device T3, the control terminal of the fourth power switch device T4, the control terminal of the fifth power switch device T5 and the control terminal of the sixth power switch device T6 are used as the control terminal of the power unit 111, which are connected to the controller, thereby realizing switching transformation under the control of the controller.

[0142] In the above solution, the power unit 111 can be constructed into a full-bridge structure power unit 111 or a half-bridge structure power unit 111 according to actual conditions, so as to be applicable to different scenarios and improve the application scope of the energy storage valve submodule.

[0143] In some embodiments, the equivalent circuit of the energy storage valve submodule includes an equivalent inductance and an equivalent internal resistance of the energy storage module; and / or, the equivalent circuit of the energy storage valve submodule includes an equivalent inductance and an equivalent internal resistance of the busbar.

[0144] Specifically, in the actual use scenario, the energy storage valve submodule may need to use a busbar to connect the energy storage module 103 according to the use requirements. The busbar between the energy storage module 103 and the power conversion module 101 has equivalent inductance and equivalent internal resistance. The equivalent inductance, equivalent internal resistance and DC support capacitor C form an RLC network, thereby generating underdamped oscillations. For the energy storage module 103, during the charging and discharging process, due to the resistance-capacitance effect of the battery, there may be equivalent internal resistance and equivalent capacitance. The equivalent internal resistance and equivalent capacitance, combined with the equivalent inductance and equivalent internal resistance of the busbar, can also form an RLC network to generate underdamped oscillations.

[0145] If the busbar is not used during the construction of the energy storage valve submodule, an RLC network will also be formed due to the resistance-capacitance effect of the battery and the equivalent stray inductance of the energy storage module 103, thereby generating under-damped oscillations. That is, in actual scenarios, the resistance-inductance-capacitance damping circuit of the energy storage valve submodule can be used to suppress the under-damped oscillations generated by the existence of the equivalent stray inductance and equivalent internal resistance of the energy storage module 103 alone; or suppress the under-damped oscillations generated by the existence of the equivalent stray inductance and equivalent internal resistance of the busbar alone; or suppress the under-damped oscillations generated when both exist at the same time.

[0146] In the above scheme, the equivalent circuit of the energy storage valve submodule may include the equivalent inductance and equivalent internal resistance of the energy storage module 103. In the actual operation process, the under-damped oscillation caused by the equivalent inductance and equivalent internal resistance of the energy storage module can be suppressed by the resistor, inductor, and capacitor damping circuit. It can also include the equivalent inductance and equivalent internal resistance of the busbar, and the under-damped oscillation caused by the equivalent inductance and equivalent internal resistance of the busbar can be suppressed by the resistor, inductor, and capacitor damping circuit. The resistor, inductor, and capacitor damping circuit has good applicability.

[0147] In order to facilitate understanding of the technical solution of the present application, the present application is explained below in conjunction with more detailed embodiments.

[0148] First, a first resistor-inductor-capacitor series branch 501 is arranged in parallel between the power conversion module 101 and the energy storage module 103. In the first resistor-inductor-capacitor series branch 501, a first end of the first resistive element R1 is connected to a first end of the power conversion module 101 and a first end (positive electrode) of the energy storage module 103, a second end of the first resistive element R1 is connected to a first end of the first inductive element L1, a second end of the first inductive element L1 is connected to a first end of the first capacitive element C1, and a second end of the first capacitive element C1 is connected to a second end of the power conversion module 101 and a second end (negative electrode) of the energy storage module 103. At this time, the admittance of the first resistor-inductor-capacitor series branch 501 can be regarded as:

[0149]

[0150] At this time, the current transfer function of the energy storage module 103 is: The admittance of the first RC series branch 501 is analogized to a second-order bandpass filter. get and Based on the idea that the current gain of the current transfer function of the energy storage module 103 at the resonant frequency is less than 0, the resonant frequency is set to 1KHz, the gain coefficient is within the range of 10-100, and the damping ratio is within the range of 0.5-5. Substitute the above mapping relationship and make precise design at the resonant frequency in combination with the upper limit of the power of the resistive element. Finally, the capacitance value of the first capacitive element C1 is in the mF level, the inductive element value of the first inductive element L1 is in the μH level, and the resistive element value of the first resistive element R1 is in the mΩ level, so as to build an energy storage valve submodule with under-damped oscillation suppression function.

[0151] Afterwards, the energy storage valve submodule is verified to obtain the Bode diagram of the current transfer function of the energy storage module 103 as shown in Fig.12 As shown, the current simulation of the energy storage module 103 is as follows Fig.13 As shown in the figure, it can be seen that the current gain of the current transfer function of the energy storage module 103 at the resonant frequency (1KHz) is suppressed to be less than 0 by the first resistor, inductor and capacitor series branch 501, and the peak value of the oscillating current of the energy storage module 103 is 2497A, which is much smaller than the peak value of the oscillating current 3684A when the first resistor, inductor and capacitor series branch 501 is not set. This solution can achieve under-damped oscillation suppression.

[0152] Furthermore, considering that the parallel connection of the first resistor, inductor, and capacitor series branch 501 may increase the current gain of the current transfer function of the energy storage module 103 in the low frequency band (i.e., the frequency band less than the resonant frequency), in order to reduce the low frequency band gain, a second resistor, inductor, and capacitor series branch 801 may be further arranged in parallel between the power conversion module 101 and the energy storage module 103, and a similar method as described above may be used to select the second resistor, inductor, and capacitor series branch 801, thereby optimizing the underdamped oscillation suppression effect.

[0153] Considering that the resonant frequency is relatively small, the second resistor-inductor-capacitor series branch 801 needs to appropriately reduce the capacitance value and / or increase the inductive element value based on the first resistor-inductor-capacitor series branch 501, that is, the capacitance value of the second capacitive element C2 is set to be greater than the capacitance value of the first capacitive element C1, and / or the inductive element value of the second inductive element L2 is set to be greater than the inductive element value of the first inductive element L1. Under this structure, the energy storage valve submodule is verified, and the Bode diagram of the current transfer function of the energy storage module 103 is obtained as shown in FIG. Fig.14 As shown, the current simulation of the energy storage module 103 is as follows Fig.15 As shown in the figure, it can be seen that the current gain of the current transfer function of the energy storage module 103 at the resonant frequency is suppressed to be less than 0 through the first resistor-inductor-capacitor series branch 501 and the second resistor-inductor-capacitor series branch 801, and the energy storage module 103 has a lower current gain in the frequency band less than the resonant frequency (1KHz). It can be seen from the figure that the peak value of the oscillating current of the energy storage module 103 is 2252A, which is much smaller than the peak value of the oscillating current 3684A when no oscillation is set. This solution can also achieve under-damped oscillation suppression.

[0154] An energy storage system comprises the above-mentioned energy storage valve submodule.

[0155] Specifically, the energy storage valve submodule is as shown in the above-mentioned embodiments and the accompanying drawings, and will not be described in detail here. In this solution, a resistor, inductor, and capacitor damping circuit 301 is arranged in parallel between the power conversion module 101 and the energy storage module 103 of the energy storage valve submodule. During the operation of the energy storage valve submodule, the resistor, inductor, and capacitor damping circuit 301 can suppress the under-damped oscillation between the power conversion module 101 and the energy storage module 103, thereby slowing down the situation where the charging and discharging current of the energy storage module 103 exceeds the rated operating current due to the oscillating current, reducing the abnormal attenuation of the life of the energy storage module 103, and thus improving the operation reliability of the energy storage valve submodule.

[0156] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; 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 included in the scope of the claims and specification of the present 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. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A storage valve submodule, characterized in that: include: Power conversion module; Energy storage module; A resistor, inductor, and capacitor damping circuit is respectively arranged in parallel with the power conversion module and the energy storage module.

2. The energy storage valve submodule according to claim 1, characterized in that: The RC damping circuit comprises a first RC series branch, wherein the first RC series branch is connected in parallel with the power conversion module and the energy storage module; The first resistor-inductor-capacitor series branch includes a first resistive element, a first inductive element and a first capacitive element, and the first resistive element, the first inductive element and the first capacitive element are arranged in series.

3. The energy storage valve submodule according to claim 2, characterized in that: The first resistor-inductor-capacitor series branch further includes a first switch, and the first switch is arranged in parallel with the first resistive element.

4. The energy storage valve submodule according to claim 2, characterized in that: The first resistor-inductor-capacitor series branch also includes a second resistive element, a second switch and a third switch, wherein the second switch is arranged in series between the first resistive element and the first inductive element, and after the third switch and the second resistive element are connected in series, they are arranged in parallel with the series branch of the first resistive element and the second switch.

5. The energy storage valve submodule according to any one of claims 2 to 4, characterized in that: The RC damping circuit further includes a second RC series branch, which is connected in parallel with the first RC series branch and the energy storage module. The second resistor-inductor-capacitor series branch includes a third resistive element, a second inductive element and a second capacitive element, and the third resistive element, the second inductive element and the second capacitive element are arranged in series.

6. The energy storage valve submodule according to claim 5, characterized in that: The second resistor-inductor-capacitor series branch further includes a fourth switch, and the fourth switch is arranged in parallel with the third resistive element.

7. The energy storage valve submodule according to claim 5, characterized in that: The second resistor-inductor-capacitor series branch also includes a fourth resistive element, a fifth switch and a sixth switch. The fifth switch is arranged in series between the third resistive element and the second inductive element. After the sixth switch and the fourth resistive element are connected in series, they are arranged in parallel with the series branch of the third resistive element and the fifth switch.

8. The energy storage valve submodule according to claim 5, characterized in that: Include at least one of the following: Item 1: The resistance value range of the first resistive element includes 1mΩ-1000mΩ; Item 2: The inductance value of the first inductive element ranges from 1uH to 1000uH; Item 3: The capacitance value range of the first capacitive element includes 1mF-1000mF.

9. The energy storage valve submodule according to claim 8, characterized in that: Include at least one of the following: Item 1: The resistance value of the first resistive element ranges from 50mΩ to 80mΩ; Item 2: The inductance value of the first inductive element ranges from 1uH to 100uH; Item 3: The capacitance value of the first capacitive element ranges from 1mF to 10mF.

10. The energy storage valve submodule according to claim 9, characterized in that: The capacitance of the second capacitive element is smaller than the capacitance of the first capacitive element, and / or the inductance of the second inductive element is larger than the inductance of the first inductive element.

11. The energy storage valve submodule according to any one of claims 1 to 4, characterized in that: The power conversion module includes a power unit and a DC support capacitor, wherein the first end of the DC support capacitor is connected to the first end of the resistor, inductor and capacitor damping circuit and the first DC end of the power unit, the second end of the DC support capacitor is connected to the second end of the resistor, inductor and capacitor damping circuit and the second DC end of the power unit, the first AC end and the second AC end of the power unit are used for cascading with other energy storage valve submodules, and the control end of the power unit is used for connecting to a controller.

12. The energy storage valve submodule according to claim 11, characterized in that: The power conversion module further includes a bypass switch, and the first AC end and the second AC end of the power unit are respectively connected to the bypass switch.

13. The energy storage valve submodule according to claim 11, characterized in that: The power unit includes a full-bridge power unit or a half-bridge power unit.

14. The energy storage valve submodule according to any one of claims 1 to 4, characterized in that: The equivalent circuit of the energy storage valve submodule includes an equivalent inductance and an equivalent internal resistance of the energy storage module; and / or the equivalent circuit of the energy storage valve submodule includes an equivalent inductance and an equivalent internal resistance of a busbar.

15. An energy storage system, characterized in that: It comprises the energy storage valve submodule as described in any one of claims 1-14.

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