WO2024051217A1

WO2024051217A1 - Battery energy storage circuit and system

Info

Publication number: WO2024051217A1
Application number: PCT/CN2023/097005
Authority: WO
Inventors: 彭鹏; 陈满; 李毓烜; 叶复萌; 李勇琦
Original assignee: 南方电网调峰调频发电有限公司储能科研院
Priority date: 2022-09-06
Filing date: 2023-05-30
Publication date: 2024-03-14
Also published as: LU505599B1; CN115473265A

Abstract

The present application relates to a battery energy storage circuit, comprising a first voltage-stabilizing bridge arm, a second voltage-stabilizing bridge arm, a first phase cluster, a second phase cluster and a third phase cluster. A first end of the first voltage-stabilizing bridge arm is configured to be connected to a first end of a DC power grid; a first end of the second voltage-stabilizing bridge arm is connected to a second end of the first voltage-stabilizing bridge arm and a neutral wire of a three-phase AC power grid, respectively, and a second end of the second voltage-stabilizing bridge arm is configured to be connected to a second end of the DC power grid; the first phase cluster comprises a first energy storage bridge arm and a second energy storage bridge arm; the second phase cluster comprises a third energy storage bridge arm and a fourth energy storage bridge arm; the third phase cluster comprises a fifth energy storage bridge arm and a sixth energy storage bridge arm.

Description

Battery energy storage circuits and systems

This application claims priority to the Chinese patent application with application number 202211084100.8, which was submitted to the China Patent Office on September 6, 2022. The entire content of this application is incorporated into this application by reference.

Technical field

The present application relates to the field of electronic circuit technology, for example, to a battery energy storage circuit and system.

Background technique

Battery energy storage is a technology that has developed rapidly in recent years. There are various battery energy storage technology routes, such as two-level battery energy storage systems with voltage grid-connection, three-level battery energy storage systems with medium voltage grid-connection and those that can realize from Low voltage to high voltage grid-connected modular battery energy storage system. Among them, the modular battery energy storage system avoids the direct large-scale series connection of power switching devices and energy storage batteries, has strong scalability, good output power quality, and is modular and easy to maintain, while the modular multi-level converter (Modula Multi- Level Converter (MMC) battery energy storage system is one of the most important application forms.

In related technologies, modular multi-level energy storage systems usually have 6 bridge arms to form a three-phase three-wire structure. They can only operate in a three-phase three-wire manner and cannot be directly used in situations where three-phase four-wire AC grid connection/power supply is required. Be applicable.

Contents of the invention

This application provides a battery energy storage circuit and system to solve the problem that the traditional three-phase three-wire structure energy storage system cannot be applied in three-phase four-wire grid connection/power supply situations.

On the one hand, this application provides a battery energy storage circuit, including:

A first voltage stabilizing bridge arm, the first end of the first voltage stabilizing bridge arm is used to connect the first end of the DC power grid;

a second voltage stabilizing bridge arm. The first end of the second voltage stabilizing bridge arm is connected to the second end of the first voltage stabilizing bridge arm and the neutral line of the three-phase AC power grid respectively. The second voltage stabilizing bridge arm The second end of the bridge arm is used to connect the second end of the DC power grid;

The first phase cluster includes a first energy storage bridge arm and a second energy storage bridge arm. The first end of the first energy storage bridge arm is used to connect the first end of the DC grid. The first energy storage bridge arm The second end of the bridge arm is connected to the first end of the second energy storage bridge arm and the first phase line of the three-phase AC power grid respectively, and the second end of the second energy storage bridge arm is used to connect all The second end of the DC grid;

The second phase cluster includes a third energy storage bridge arm and a fourth energy storage bridge arm. The first end of the third energy storage bridge arm is used to connect the first end of the DC grid. The third energy storage bridge arm The second end of the bridge arm is connected to the first end of the fourth energy storage bridge arm and the second phase line of the three-phase AC power grid respectively, and the second end of the fourth energy storage bridge arm is used to connect all The second end of the DC grid;

The third phase cluster includes a fifth energy storage bridge arm and a sixth energy storage bridge arm. The first end of the fifth energy storage bridge arm is used to connect the first end of the DC grid. The fifth energy storage bridge arm The second end of the bridge arm is connected to the first end of the sixth energy storage bridge arm and the third phase line of the three-phase AC power grid respectively, and the second end of the sixth energy storage bridge arm is used to connect all The second end of the DC grid.

The second aspect of this application provides a battery energy storage system, including: a three-phase AC power grid, including a first phase line, a second phase line, a third phase line and a neutral line, and as described in any of the foregoing embodiments. The battery energy storage circuit described above, wherein the battery energy storage circuit is connected to the first phase line, the second phase line, the third phase line and the neutral line respectively.

Description of the drawings

The drawings needed to be used in the embodiments will be briefly introduced below. The drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without exerting creative efforts, Other drawings can also be obtained from these drawings.

Figure 1 is a schematic structural diagram of a battery energy storage circuit in an embodiment provided by this application;

Figure 2 is a schematic structural diagram of a battery energy storage circuit in another embodiment provided by this application;

Figure 3 is a schematic structural diagram of a voltage stabilizing unit in an embodiment provided by this application;

Figure 4 is a schematic structural diagram of an energy storage unit in an embodiment provided by this application.

Detailed ways

In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are given in the accompanying drawings. However, the present application may be embodied in many different forms, and these embodiments are provided so that the disclosure of the present application will be thorough and comprehensive.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only.

It will be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to compare the first element to another Component differentiation.

It should be noted that when an element is said to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intervening element. In addition, "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

As used herein, the singular forms "a," "an," and "the" may include the plural forms as well, unless the context clearly dictates otherwise. It will also be understood that the terms "comprising" or "having" and the like specify the presence of stated features, integers, steps, operations, components, parts or combinations thereof, but do not exclude the presence or addition of one or more Possibility of other features, integers, steps, operations, components, parts or combinations thereof.

In one embodiment of the present application, as shown in Figure 1, a battery energy storage circuit is provided, including a first voltage stabilizing bridge arm 10, a second voltage stabilizing bridge arm 20, a first phase cluster 30, a second phase cluster 40 and the third phase cluster 50, wherein the first end of the first voltage stabilizing bridge arm 10 is used to connect the first end of the DC power grid; the first end of the second voltage stabilizing bridge arm 20 is connected to the first voltage stabilizing bridge arm respectively. The second end of 10 is connected to the neutral line of the three-phase AC power grid, and the second end of the second voltage stabilizing bridge arm 20 is used to connect to the second end of the DC power grid; the first phase cluster 30 includes a first energy storage bridge arm 31 and the second energy storage bridge arm 32. The first end of the first energy storage bridge arm 31 is used to connect the first end of the DC grid, and the second end of the first energy storage bridge arm 31 is connected to the second energy storage bridge arm 32 respectively. The first end of the three-phase AC power grid is connected to the first phase line, and the second end of the second energy storage bridge arm 32 is used to connect to the second end of the DC power grid; the second phase cluster 40 includes a third energy storage bridge arm 41 and the fourth energy storage bridge arm 42. The first end of the third energy storage bridge arm 41 is used to connect the first end of the DC grid, and the second end of the third energy storage bridge arm 41 is connected to the fourth energy storage bridge arm 42 respectively. The first end of the three-phase AC power grid is connected to the second phase line, and the second end of the fourth energy storage bridge arm 42 is used to connect the second end of the DC power grid; the third phase cluster 50 includes a fifth energy storage bridge arm 51 and the sixth energy storage bridge arm 52. The first end of the fifth energy storage bridge arm 51 is used to connect the first end of the DC grid, and the second end of the fifth energy storage bridge arm 51 is connected to the sixth energy storage bridge arm 52 respectively. The first end of the sixth energy storage bridge arm 52 is connected to the third phase line of the three-phase AC power grid, and the second end of the sixth energy storage bridge arm 52 is used to connect to the second end of the DC power grid.

In the battery energy storage circuit described in the above embodiment, by providing the first voltage stabilizing bridge arm 10 and the second voltage stabilizing bridge arm 20, on the one hand, the output voltage at the DC grid end can be stabilized, and on the other hand, through the first voltage stabilizing bridge The midpoint of the arm 10 and the second voltage stabilizing bridge arm 20 can provide a stable reference voltage, thereby providing a stable neutral point for the subsequent AC power grid, so that the battery energy storage circuit can meet the operation requirements of the three-phase four-wire power grid.

As an example, please refer to Figure 2. The first voltage stabilizing bridge arm 10 includes a plurality of first voltage stabilizing units S ₁ arranged in cascade, in which the first end of the first-stage first voltage stabilizing unit S ₁₁ serves as the first stabilizing unit. The first end of the voltage stabilizing arm 10 and the second end of the last stage first voltage stabilizing unit S _1N serve as the second end of the first voltage stabilizing bridge arm 10; the second voltage stabilizing unit The bridge arm 20 includes a plurality of second voltage stabilizing units S ₂ arranged in cascade, wherein the first end of the second voltage stabilizing unit S ₂₁ of the first stage serves as the first end of the second voltage stabilizing bridge arm 20 , and the last stage The second end of the second voltage stabilizing unit S _2N serves as the second end of the second voltage stabilizing bridge arm 20 . In some embodiments, the number of first voltage stabilizing units S ₁ and the number of second voltage stabilizing units S ₂ are equal. In any voltage stabilizing bridge arm, multiple voltage stabilizing units serve as backup for each other, which improves the working stability of the voltage stabilizing bridge arm. In actual work, by controlling the input of the first voltage stabilizing bridge arm and the second voltage stabilizing bridge arm, The number of voltage stabilizing units ensures that the voltages of the upper and lower voltage stabilizing bridge arms are equal and both are U _dc /2, where U _dc is the output voltage of the DC grid. Therefore, on the one hand, it ensures that the first voltage stabilizing bridge arm and the second stabilizing bridge arm The sum of the voltages of the voltage-stabilizing bridge arms is the output voltage U _dc of the DC grid, achieving a voltage stabilizing effect. On the other hand, by controlling the input end of the first voltage-stabilizing bridge arm to be the forward voltage U _dc /2, the second voltage-stabilizing arm is controlled The output terminal voltage of the bridge arm is a negative voltage - U _dc /2, so that the midpoint voltage of the first voltage stabilizing bridge arm and the second voltage stabilizing bridge arm is 0 and can remain relatively stable, thereby providing AC for the subsequent stage. The power grid provides a stable neutral point and provides power for the three-phase four-wire power grid.

As an example, please refer to Figure 3. The first voltage stabilizing unit S ₁ and the second voltage stabilizing unit S ₂ respectively include: a first switching tube T ₁ , a second switching tube T ₂ , a first diode D ₁ , and a second switching tube T 2 . Diode D ₂ and voltage stabilizing capacitor C ₀ , where the control end of the first switching transistor T ₁ is used to receive the first control signal, and the first end of the first switching transistor T ₁ is connected to the first diode D ₁ respectively. The cathode and the first end of the voltage stabilizing capacitor C ₀ are connected, the second end of the first switching tube T ₁ is connected to the anode of the first diode D ₁ , and the second end of the first switching tube T ₁ serves as the first stabilizing capacitor. The first end of the voltage unit S ₁ and the second voltage stabilizing unit S ₂ ; the control end of the second switching tube T ₂ is used to receive the second control signal, and the first end of the second switching tube T ₂ is connected to the second diode respectively. The cathode of tube D ₂ is connected to the second end of the first switching tube T ₁ , and the second end of the second switching tube T ₂ is connected to the anode of the second diode D ₂ and the second end of the voltage stabilizing capacitor C ₀ respectively. , the second terminal of the second switching tube T ₂ serves as the second terminal of the first voltage stabilizing unit S ₁ and the second voltage stabilizing unit S ₂ ; wherein the first switching tube T ₁ is under the action of the first control signal, and The second switch transistor T ₂ is turned on at the same time or in a time-sharing manner under the action of the second control signal. In some embodiments, the drive control signals of the first switching tube T ₁ and the second switching tube T ₂ may use DC as the carrier phase shift of the modulated wave, that is, the switching devices of each voltage stabilizing unit use the same The modulation wave generates a PWM modulation wave, and the carrier waves of adjacent voltage stabilizing units differ by the same phase angle. The sum of the phase angles of all voltage stabilizing units is 2π, π is the pi, and the first switching tube T ₁ and the second switching tube _T2 can also be put into operation in a cyclical rotation mode. By cyclically switching the input of the voltage stabilizing unit, the input number of the voltage stabilizing unit and the output of the voltage stabilizing unit of the first voltage stabilizing bridge arm and the second voltage stabilizing bridge arm are maintained. The products of the voltages are all U _dc /2. Workers in this field can choose the switch control method according to their needs.

As an example, please continue to refer to Figure 2, the first energy storage bridge arm 31, the second energy storage bridge arm 32, the third energy storage bridge arm 41, the fourth energy storage bridge arm 42, the fifth energy storage bridge arm 51, the Each of the six energy storage bridge arms 52 includes a plurality of energy storage units arranged in cascade, and the two energy storage bridge arms in the same phase cluster each include the same number of energy storage units. In some embodiments, the input number of energy storage units in each energy storage bridge arm can be controlled to generate a three-phase AC voltage with a phase difference of 120° at the three-phase AC inlet.

In one embodiment, the first energy storage bridge arm 31, the second energy storage bridge arm 32, the third energy storage bridge arm 41, the fourth energy storage bridge arm 42, the fifth energy storage bridge arm 51, the sixth energy storage bridge arm 51, and the sixth energy storage bridge arm 42. The energy bridge arms 52 respectively include the same number of energy storage units, first voltage stabilizing units, and second voltage stabilizing units.

As an example, please refer to Figure 4. The energy storage unit includes a third switching tube T ₃ , a fourth switching tube T ₄ , a third diode D ₃ , a fourth diode D ₄ and an energy storage device U, where the The control terminal of the three switch tube T ₃ is used to receive the third control signal. The first terminal of the third switch tube T ₃ is connected to the cathode of the third diode D ₃ and the positive terminal of the energy storage device U respectively. The second end of the tube T ₃ is connected to the anode of the third diode D ₃ , the second end of the third switching tube T ₂ serves as the first end of the voltage stabilizing unit; the control end of the fourth switching tube T ₄ is used to receive The fourth control signal, the first end of the fourth switching tube T ₄ is connected to the cathode of the fourth diode D ₄ and the second end of the third switching tube T ₃ respectively, and the second end of the fourth switching tube T _{4 is respectively connected to the cathode of the fourth diode D 4} and the second end of the third switching tube T 3 Connected to the anode of the fourth diode D ₄ and the negative terminal of the energy storage device U, the second end of the fourth switching tube T ₄ serves as the second end of the voltage stabilizing unit; wherein, the third switching tube T ₃ Under the action of the control signal, the fourth switching transistor T ₄ is turned on at the same time or in a time-sharing manner under the action of the fourth control signal. In some embodiments, through the modulation method of the driving signals of the third switching tube T ₃ and the fourth switching tube T ₄ , a three-phase alternating current with a phase difference of 120° is used as the carrier phase shift of the modulated wave, that is, the bridge arms are in different phases. The carrier waves are exactly the same, but the phase difference of the modulation waves is 120°. On the same bridge arm, the carrier phases of adjacent energy storage units differ by the same phase angle. The sum of the phase angle differences of all energy storage units is 2π.

Optionally, the specific type of the energy storage device U is not unique. In some embodiments, the energy storage device U may be a battery. Optionally, a lithium titanate battery can be used as the energy storage device U. For example, the lithium titanate battery used has a rated voltage of 48V and a nominal capacity of 55Ah. In the same way, the specific types of the first switch tube T ₁ , the second switch tube T ₂ , the third switch tube T ₃ and the fourth switch tube T ₄ are not unique. For example, the first switch tube T ₁ , the second switch tube T 4 The transistor T ₂ , the third switching transistor T ₃ and the fourth switching transistor T ₄ may all be metal oxide semiconductor field effect transistors. In some embodiments, in order to ensure that the battery energy storage system can be used in a higher voltage environment, the selected MOSFET should have a withstand voltage value of 100V-150V. Optionally, in a more detailed In the embodiment, the power MOSFET model SFG180N10PF is selected as the switching device of the energy storage unit. The continuous drain current it can allow is 180A, and the pulse drain current it can withstand is 540A. In the same voltage stabilizing unit, two MOSFETs are connected in a half-bridge structure and connected in parallel with the voltage stabilizing capacitor C _0. The capacity of the voltage stabilizing capacitor C ₀ can be 6800uF. In the same energy storage unit, two MOSFETs are connected in a half-bridge structure and are connected in parallel with the filter capacitor C ₁ and the energy storage device U. The capacity of the filter capacitor C ₁ can be 6800uF.

As an example, please continue to refer to Figure 4. The energy storage unit also includes a filter capacitor C ₁ , in which the first end of the filter capacitor C ₁ is connected to the positive terminal of the energy storage device U, and the second end of the filter capacitor C ₁ is connected to the energy storage device U. The negative terminal of device U is connected.

As an example, please continue to refer to Figure 2. The battery energy storage circuit also includes a first inductor L ₁ , a second inductor L ₂ , a third inductor L ₃ , a fourth inductor L ₄ , a fifth inductor L ₅ , and a sixth inductor L ₆ , the seventh inductor L ₇ and the eighth inductor L ₈ , wherein the first inductor L ₁ is respectively connected to the second end of the first voltage stabilizing bridge arm 10 and the first common endpoint, and the first common endpoint is the first voltage stabilizing bridge arm. The end point between the second end of 10 and the first end of the second voltage stabilizing bridge arm 20 and connected to the neutral line; the second inductor L ₂ is respectively connected to the first end of the second voltage stabilizing bridge arm 20 and the first common endpoint; the third inductor L ₃ is connected to the second end of the first energy storage bridge arm 31 and the second common endpoint respectively, and the second common endpoint is the second end of the first energy storage bridge arm 31 and the second energy storage bridge arm 32 between the first ends and connected to the first phase line; the fourth inductor L ₄ is connected to the first end and the second common end of the second energy storage bridge arm 32 respectively; the fifth inductor L ₅ is connected to the third storage bridge arm 32 respectively. The second end of the energy storage bridge arm 41 and the third common endpoint. The third common endpoint is between the second end of the third energy storage bridge arm 41 and the first end of the fourth energy storage bridge arm 42 and with the second phase line. The end points of the connection; the sixth inductor L ₆ is respectively connected to the first end and the third common end of the fourth energy storage bridge arm 42; the seventh inductor L ₇ is respectively connected to the second end of the fifth energy storage bridge arm 51 and the fourth common end. endpoint, the first common endpoint is the endpoint between the second end of the fifth energy storage bridge arm 51 and the first end of the sixth energy storage bridge arm 52 and connected to the third phase line; the eighth inductor L ₈ is connected to the third phase line respectively. The first end and the fourth common end of the six energy storage bridge arms 52.

As an example, please continue to refer to Figure 2. The battery energy storage circuit also includes: a ninth inductor L ₉ , a tenth inductor L ₁₀ and an eleventh inductor L ₁₁ . The ninth inductor L ₉ is connected to the second common endpoint and the first inductor L 11 respectively. One phase line; the tenth inductor L ₁₀ is connected to the third common terminal and the second phase line respectively; the ninth inductor L ₁₁ is connected to the fourth common terminal and the third phase line respectively.

The second aspect of this application provides a battery energy storage system, including: a three-phase AC power grid, including a first phase line, a second phase line, a third phase line and a neutral line, and as in any one of the preceding embodiments A battery energy storage circuit, wherein the battery energy storage circuit is connected to the first phase line, the second phase line, the third phase line and the neutral line respectively.

The present application will be explained below with reference to specific embodiments. The battery energy storage system of this embodiment is used in a 60kW/380V battery energy storage system, and the DC side rated voltage is 750V. The rated capacity of the transformer in the distribution network connected to the battery energy storage system is 250kVA. The voltage stabilizing unit of this embodiment includes two switching devices, a freewheeling diode, and a voltage stabilizing capacitor C ₀ , which are connected in parallel to form a voltage stabilizing unit. The energy storage unit includes Two switching devices and freewheeling diodes, a filter capacitor C ₁ and an energy storage battery U are connected in parallel to form an energy storage unit. Each bridge arm has 20 energy storage units, which are connected as shown in Figure 1 to form the entire battery energy storage system. Among them, the energy storage battery U of the energy storage unit is a lithium titanate battery with a rated voltage of 48V and a nominal capacity of 55Ah. The bridge arms connected between each bridge arm are connected to inductors (i.e., the first inductor L ₁ to the eighth inductor L ₈ ) The inductance values are all 1mH. After considering the filtering effect of the AC side connected inductors (i.e. the ninth inductor L ₁ to the eleventh inductor L ₁₁ ), the inductance value is selected to be 1mH. The first switching tube T ₁ , the second switching tube T ₂ , the third switching tube T ₃ and the fourth switching tube T ₄ are MOSFETs with a withstand voltage of 100V-150V. The MOSFET model SFG180N10PF is selected as the switching device, which can allow The continuous drain current passed is 180A, and the pulsed drain current it can withstand is 540A. In the same voltage stabilizing unit, two MOSFETs are connected in a half-bridge structure and connected in parallel with the voltage stabilizing capacitor C _0. The capacity of the voltage stabilizing capacitor C ₀ can be 6800uF. In the same energy storage unit, two MOSFETs are connected in a half-bridge structure and are connected in parallel with the filter capacitor C ₁ and the energy storage device U. The capacity of the filter capacitor C ₁ can be 6800uF. Assume that the positive terminal voltage of the DC grid is +U _dc /2 and the negative terminal voltage is -U _dc /2. The voltage stabilizing unit uses DC as the carrier phase shift of the modulated wave, or each voltage stabilizing unit is connected in turn to maintain the neutral line voltage of the three-phase AC power grid at 0, and the driving signal of the switching device in the energy storage unit is The modulation method uses three-phase alternating current with a phase difference of 120° as the carrier phase shift of the modulated wave, so that the voltage at the three-phase AC outlet is maintained as a three-phase alternating current with a phase difference of 120°.

It should be noted that in the embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the system embodiments described above are only illustrative. For example, the division of the units can be a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or can be Integrated into another system, or some features can be ignored, or not implemented. On the other hand, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the units or modules may be in electrical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed to multiple units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application can be integrated into one processing unit, each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware.

Claims

A battery energy storage circuit including:

A first voltage stabilizing bridge arm, the first end of the first voltage stabilizing bridge arm is used to connect the first end of the DC power grid;

a second voltage stabilizing bridge arm. The first end of the second voltage stabilizing bridge arm is connected to the second end of the first voltage stabilizing bridge arm and the neutral line of the three-phase AC power grid respectively. The second voltage stabilizing bridge arm The second end of the bridge arm is used to connect the second end of the DC power grid;

The first phase cluster includes a first energy storage bridge arm and a second energy storage bridge arm. The first end of the first energy storage bridge arm is used to connect the first end of the DC grid. The first energy storage bridge arm The second end of the bridge arm is connected to the first end of the second energy storage bridge arm and the first phase line of the three-phase AC power grid respectively, and the second end of the second energy storage bridge arm is used to connect all The second end of the DC grid;

The second phase cluster includes a third energy storage bridge arm and a fourth energy storage bridge arm. The first end of the third energy storage bridge arm is used to connect the first end of the DC grid. The third energy storage bridge arm The second end of the bridge arm is connected to the first end of the fourth energy storage bridge arm and the second phase line of the three-phase AC power grid respectively, and the second end of the fourth energy storage bridge arm is used to connect all The second end of the DC grid;

The third phase cluster includes a fifth energy storage bridge arm and a sixth energy storage bridge arm. The first end of the fifth energy storage bridge arm is used to connect the first end of the DC grid. The fifth energy storage bridge arm The second end of the bridge arm is connected to the first end of the sixth energy storage bridge arm and the third phase line of the three-phase AC power grid respectively, and the second end of the sixth energy storage bridge arm is used to connect all The second end of the DC grid.
The battery energy storage circuit according to claim 1, wherein the first voltage stabilizing bridge arm includes a plurality of first voltage stabilizing units arranged in cascade, wherein the first voltage stabilizing unit in the first stage The end is used as the first end of the first voltage stabilizing bridge arm, and the second end of the first voltage stabilizing unit of the last stage is used as the second end of the first voltage stabilizing bridge arm;

The second voltage stabilizing bridge arm includes a plurality of second voltage stabilizing units arranged in cascade, wherein the first end of the second voltage stabilizing unit in the first stage serves as the first end of the second voltage stabilizing bridge arm. , the second end of the second voltage stabilizing unit of the last stage serves as the second end of the second voltage stabilizing bridge arm.
The battery energy storage circuit according to claim 2, wherein the number of the first voltage stabilizing units is equal to the number of the second voltage stabilizing units.
The battery energy storage circuit according to claim 2, wherein the first voltage stabilizing unit and the second voltage stabilizing unit respectively include: a first switching tube, a second switching tube, a first diode, a second diode. tube and voltage stabilizing capacitor, where,

The control end of the first switch tube is used to receive the first control signal. The first end of the first switch tube is connected to the cathode of the first diode and the first end of the voltage stabilizing capacitor respectively. The second end of the first switch tube is connected to the anode of the first diode, and the second end of the first switch tube serves as the The first voltage stabilizing unit and the first end of the second voltage stabilizing unit;

The control end of the second switch tube is used to receive a second control signal. The first end of the second switch tube is connected to the cathode of the second diode and the second end of the first switch tube respectively. , the second end of the second switch tube is connected to the anode of the second diode and the second end of the voltage stabilizing capacitor respectively, and the second end of the second switch tube serves as the first stabilizing capacitor. voltage unit and the second end of the second voltage stabilizing unit; wherein the first switching tube is under the action of the first control signal, and the second switching tube is under the action of the second control signal. conduction at the same time or time-sharing.
The battery energy storage circuit according to claim 2, wherein the first energy storage bridge arm, the second energy storage bridge arm, the third energy storage bridge arm, the fourth energy storage bridge arm, The fifth energy storage bridge arm and the sixth energy storage bridge arm each include a plurality of energy storage units arranged in cascade.
The battery energy storage circuit according to claim 5, wherein the two energy storage bridge arms in the same phase cluster respectively include the same number of energy storage units.
The battery energy storage circuit according to claim 6, wherein the first energy storage bridge arm, the second energy storage bridge arm, the third energy storage bridge arm, the fourth energy storage bridge arm, The fifth energy storage bridge arm and the sixth energy storage bridge arm respectively include the same number of energy storage units, the number of the first voltage stabilizing units, and the number of the second voltage stabilizing units.
The battery energy storage circuit according to claim 7, wherein the energy storage unit includes a third switching tube, a fourth switching tube, a third diode, a fourth diode and an energy storage device, wherein,

The control terminal of the third switch tube is used to receive the third control signal, and the first terminal of the third switch tube is connected to the cathode of the third diode and the positive terminal of the energy storage device respectively, so The second end of the third switch tube is connected to the anode of the third diode, and the second end of the third switch tube serves as the first end of the voltage stabilizing unit;

The control end of the fourth switch tube is used to receive a fourth control signal. The first end of the fourth switch tube is connected to the cathode of the fourth diode and the second end of the third switch tube respectively. , the second end of the fourth switch tube is connected to the anode of the fourth diode and the negative terminal of the energy storage device respectively, and the second end of the fourth switch tube serves as the voltage stabilizing unit. The second end; wherein, the third switching tube is turned on at the same time or in a time-sharing manner under the action of the third control signal, and the fourth switching tube is turned on at the same time or in time division under the action of the fourth control signal.
The battery energy storage circuit according to claim 8, wherein the energy storage unit includes a filter capacitor, wherein the first end of the filter capacitor is connected to the positive terminal of the energy storage device, and the third end of the filter capacitor The two terminals are connected to the negative terminal of the energy storage device.
The battery energy storage circuit according to any one of claims 1 to 9, further comprising: a first inductor, a second inductor, a third inductor, a fourth inductor, a fifth inductor, a sixth inductor, seventh inductor and the eighth inductor, where,

The first inductor is respectively connected to the second end of the first voltage stabilizing bridge arm and a first common endpoint, and the first common endpoint is the second end of the first voltage stabilizing bridge arm and the second stabilizing bridge arm. an end point between the first ends of the pressure bridge arms and connected to the neutral line;

The second inductor is respectively connected to the first end of the second voltage stabilizing bridge arm and the first common terminal;

The third inductor is respectively connected to the second end of the first energy storage bridge arm and a second common endpoint, and the second common endpoint is the second end of the first energy storage bridge arm and the second storage endpoint. The endpoint between the first ends of the bridge arms and connected to the first phase line;

The fourth inductor is respectively connected to the first end of the second energy storage bridge arm and the second common endpoint;

The fifth inductor is respectively connected to the second end of the third energy storage bridge arm and a third common endpoint, and the third common endpoint is the second end of the third energy storage bridge arm and the fourth storage endpoint. The endpoint between the first ends of the bridge arms and connected to the second phase line;

The sixth inductor is respectively connected to the first end of the fourth energy storage bridge arm and the third common endpoint;

The seventh inductor is respectively connected to the second end and the fourth common endpoint of the fifth energy storage bridge arm. The first common endpoint is the second end of the fifth energy storage bridge arm and the sixth storage endpoint. The endpoint between the first ends of the bridge arms and connected to the third phase line;

The eighth inductor is respectively connected to the first end of the sixth energy storage bridge arm and the fourth common endpoint.
The battery energy storage circuit according to claim 10, wherein the battery energy storage circuit further includes: a ninth inductor, a tenth inductor and an eleventh inductor, wherein,

The ninth inductor is connected to the second common terminal and the first phase line respectively;

The tenth inductor is respectively connected to the third common terminal and the second phase line;

The ninth inductor is respectively connected to the fourth common terminal and the third phase line.
A battery energy storage system, including: a three-phase AC power grid, including a first phase line, a second phase line, a third phase line and a neutral line, and the battery energy storage system as claimed in any one of claims 1-11 circuit, wherein the battery energy storage circuit is connected to the first phase line, the second phase line, the third phase line and the neutral line respectively.