Energy storage converter for all-vanadium redox flow battery system

Abstract

The utility model relates to an energy storage converter for an all-vanadium redox flow battery system, which comprises an input isolation circuit, a power transmission circuit and an initial charging circuit, and the initial charging circuit comprises two direct current charging buses used for connecting the positive electrode and the negative electrode of an all-vanadium redox flow battery. The two direct current charging buses are respectively provided with a group of electrical switches S1 and a group of main switches S2, two ends of the main switch S2 of one direct current charging bus are connected in parallel with a multi-stage initial charging circuit, the multi-stage initial charging circuit comprises a plurality of initial charging branches which are connected in parallel, and each stage of initial charging branch comprises a branch switch and a protective resistor which are connected in series. According to the energy storage converter for the all-vanadium redox flow battery system, the all-vanadium redox flow battery is initially charged step by step through alternating-current pre-charging and multi-stage charging, and is converted into a normal charging and discharging mode after the normal voltage value of the battery is reached during the initial charging, so that the stable transition of the initial charging stage is realized, and the charging efficiency and the battery performance of the all-vanadium redox flow battery are further improved; and the battery life is prolonged.

Description

Technical Field

[0001] The utility model relates to the field of power energy storage technology and equipment, and particularly relates to an energy storage converter for a vanadium redox flow battery system. Background Art

[0002] At present, in the field of power energy storage technology, vanadium redox flow batteries have attracted much attention due to their long service life, large stored energy, high energy efficiency, and good environmental adaptability. When a vanadium redox flow battery is initially started, it needs to be initially charged to activate the battery and bring it to an operating state. This step is very important for the performance and life of the battery. However, the existing charging methods usually rely on external power sources or standard charging equipment for initial charging, and cannot well control the initial charging process to smoothly enter the subsequent constant voltage or constant current charging stage, and may lead to a decrease in battery efficiency or a shortening of battery life during the charging stage. Summary of the Utility Model

[0003] The technical problem to be solved by the utility model is to overcome the defect of the existing external source charging technology that cannot well control the initial charging process, and provide an energy storage converter for a vanadium redox flow battery system, which initially charges the vanadium redox flow battery through AC pre-charging and multi-stage charging, and switches to the normal charge and discharge mode after the initial charge reaches the normal voltage value of the battery, realizing a smooth transition in the initial charging stage, thereby improving the charging efficiency, battery performance of the vanadium redox flow battery, and extending the battery life.

[0004] The energy storage converter for the vanadium redox flow battery system includes an input isolation circuit, a power transmission circuit, and an initial charging circuit. The power grid charges the vanadium redox flow battery through the isolation circuit, the power transmission circuit, and the initial charging circuit in sequence. Among them, the initial charging circuit includes two DC charging buses for connecting the positive and negative electrodes of the vanadium redox flow battery. A group of electrical switches S1 and a group of main switches S2 are provided on both DC charging buses. A multi-stage initial charging circuit is connected in parallel across the main switch S2 of one of the DC charging buses. The multi-stage initial charging circuit includes several parallel initial charging branches, and each initial charging branch includes a series-connected branch switch and a protection resistor.

[0005] Further, the multi-stage initial charging circuit includes a total of three parallel initial charging branches.

[0006] Optimally, the power transmission circuit includes a main power circuit and a rectifier bridge pre-charging circuit, and the rectifier bridge pre-charging circuit is connected in parallel across the main power circuit.

[0007] Further, the main power circuit is a two-level or three-level, single-phase or three-phase bridge rectifier and inverter circuit.

[0008] The utility model relates to an energy storage converter for a vanadium redox flow battery system, which overcomes the defect of the existing external power source charging technology that cannot well control the initial charging process. The vanadium redox flow battery is initially charged by AC pre-charging and multi-stage charging step by step, and after the initial charge reaches the normal voltage value of the battery, it switches to the normal charge and discharge mode, realizing a smooth transition in the initial charging stage, thereby improving the charging efficiency, battery performance of the vanadium redox flow battery, and extending the battery life. Description of the Drawings

[0009] The following further describes the energy storage converter for a vanadium redox flow battery system of the present utility model with reference to the drawings:

[0010] Figure 1 is the logic structure and connection principle block diagram of the energy storage converter for the vanadium redox flow battery system;

[0011] Figure 2 is the internal circuit diagram of the initial charging circuit of the energy storage converter for the vanadium redox flow battery system;

[0012] Figure 3 is the internal logic structure block diagram of the power transmission circuit of the energy storage converter for the vanadium redox flow battery system;

[0013] Figure 4 is the switch action timing diagram of the initial charging process of the initial charging circuit of the energy storage converter for the vanadium redox flow battery system.

[0014] In the figure:

[0015] 1 - Input isolation circuit;

[0016] 2 - Power transmission circuit; 21 - Main power circuit, 22 - Rectifier bridge pre-charging circuit

[0017] 3 - Initial charging circuit; 31 - DC charging bus, 32 - Multi-stage initial charging circuit, 33 - Initial charging branch; 331 - Series branch switch, 332 - Protection resistor. Detailed Embodiment

[0018] In the present utility model, unless otherwise clearly defined and limited, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal connection or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0019] In the description of the present utility model, it should be understood that the orientation or positional relationships indicated by the terms "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc. are all based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model.

[0020] The following uses specific embodiments to further describe the technical solution of the present utility model, but the protection scope of the present utility model is not limited to the following embodiments.

[0021] Embodiment 1: As Figure 1 , 2 shown, the energy storage converter for a vanadium redox flow battery system includes an input isolation circuit 1, a power transmission circuit 2, and an initial charging circuit 3. The power grid charges the vanadium redox flow battery through the isolation circuit 1, the power transmission circuit 2, and the initial charging circuit 3 in sequence. Among them, the initial charging circuit 3 includes two DC charging buses 31 for connecting the positive and negative electrodes of the vanadium redox flow battery. A set of electrical switches S1 and a set of main switches S2 are provided on both DC charging buses 31. A multi-stage initial charging circuit 32 is connected in parallel across the main switch S2 of one of the DC charging buses 31. The multi-stage initial charging circuit 32 includes several parallel initial charging branches 33. Each initial charging branch 33 includes a series-connected branch switch 331 and a protection resistor 332. The main switch S2 on the positive and negative input port sides of the initial charging circuit is used to short-circuit the initial charging resistor after the initial charging is completed; the initial charging branches of the multi-stage initial charging circuit are connected in parallel with each other. The number of stages N of the initial charging branches is related to the charging current allowed during the initial charging process of the vanadium redox flow battery and the initial charging resistor. Generally, it can be set to 3 stages, such as Figure 2 shown in the first, second, and third initial charging branches; the smaller the charging current allowed by the vanadium redox flow battery during the initial charging stage, the larger the protection resistor is set; the electrical switch S1 at the positive and negative output ends of the initial charging protection circuit serves as an electrical disconnection point and is used for output disconnection in the shutdown or fault state.

[0022] Embodiment 2: The multi-stage initial charging circuit 32 of the energy storage converter for a vanadium redox flow battery system of the present utility model altogether includes three parallel initial charging branches 33. The remaining structures and components are as described in Embodiment 1 and will not be repeated here.

[0023] Embodiment 3: As Figure 3As shown, the power transmission circuit 2 of the energy storage converter for the all-vanadium redox flow battery system includes a main power circuit 21 and a rectifier bridge pre-charge circuit 22, and the rectifier bridge pre-charge circuit 22 is connected in parallel on both sides of the main power circuit 21. The remaining structures and components are as described in Embodiment 1 and will not be repeated. The main power circuit 21 of the energy storage converter for the all-vanadium redox flow battery system adopts a two-level or three-level, single-phase or three-phase bridge rectifier-inverter circuit. The remaining structures and components are as described in Embodiment 1 and will not be repeated. The rectifier bridge pre-charge circuit is used to gradually raise the DC bus voltage during the initial charge stage, and the two-level or three-level, single-phase or three-phase bridge rectifier-inverter circuit of the main power circuit performs constant voltage or constant current AC-DC conversion for high-power constant voltage or constant current charging after the initial charge is completed. The remaining structures and components are as described in Embodiment 1 and will not be repeated.

[0024] During operation: First, the rectifier bridge pre-charge circuit is used to pre-charge the DC bus inside the all-vanadium redox flow battery energy storage converter. Under the action of the AC power grid and the rectifier bridge pre-charge circuit, the DC bus voltage gradually rises. After the DC bus is pre-charged to the voltage threshold Vth (the voltage threshold Vth can be set according to the amplitude of the grid voltage), the system determines that the AC pre-charge is completed; as Figure 4 shown, after the AC pre-charge is completed, the system controls the initial charging of the all-vanadium redox flow battery. The energy storage converter first closes the electrical switch S1 at time t0, judges step by step according to the detected battery terminal voltage, and closes the branch switches S3 - S5 in the initial charging protection circuit step by step. After the initial charging is completed, the main switch S2 is closed and the branch switches S3 - S5 are opened; finally, the main power circuit runs for normal constant voltage or constant current charging.

[0025] The energy storage converter for the all-vanadium redox flow battery system overcomes the defect of the existing external source charging technology in the inability to well control the initial charge process. It performs initial charging on the all-vanadium redox flow battery through AC pre-charge and multi-stage charging step by step, and switches to the normal charge and discharge mode after the initial charge reaches the normal voltage value of the battery, realizing a smooth transition in the initial charge stage, thereby improving the charging efficiency, battery performance of the all-vanadium redox flow battery, and extending the battery life.

[0026] The above description shows the main features, basic principles, and advantages of the present utility model. For those skilled in the art, it is obvious that the present utility model is not limited to the details of the above-described exemplary embodiments or examples, and can be implemented in other specific forms without departing from the spirit or basic features of the present utility model. Therefore, the above-described embodiments or examples should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present utility model. Any reference signs in the claims should not be construed as limiting the claims involved.

[0027] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An energy storage converter for an all-vanadium liquid flow battery system, characterized in that: Include input An isolation circuit (1), a power transmission circuit (2), and an initial charging circuit (3), wherein the power grid charges the all-vanadium liquid flow battery via the isolation circuit (1), the power transmission circuit (2), and the initial charging circuit (3) in sequence, wherein: The initial charging circuit (3) comprises two DC charging busbars (31) for connecting the positive and negative electrodes of the all-vanadium liquid flow battery, each of which is provided with a group of electrical switches S1 and a group of main switches S2, wherein two ends of the main switch S2 of one DC charging busbar (31) are connected in parallel with a multi-stage initial charging circuit (32), the multi-stage initial charging circuit (32) comprising a plurality of parallel initial charging branches (33), each stage of the initial charging branch (33) comprising a branch switch (331) and a protective resistor (332) connected in series.

2. The energy storage converter for the all-vanadium liquid flow battery system according to claim 1 is characterized in that: The multi-stage initial charging circuit (32) comprises a total of three parallel initial charging branches (33).

3. The energy storage converter for the all-vanadium liquid flow battery system according to claim 2 is characterized in that: The power transmission circuit (2) comprises a main power circuit (21) and a rectifier bridge pre-charging circuit (22), wherein the rectifier bridge pre-charging circuit (22) is connected in parallel to the main power circuit (21).

4. The energy storage converter for the all-vanadium liquid flow battery system according to claim 3 is characterized in that: The main power circuit (21) adopts a two-level or three-level, single-phase or three-phase bridge rectifier inverter circuit.

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