All-vanadium redox flow battery DCDC type equalization system and electric energy equalization method thereof

Abstract

The invention relates to an all-vanadium redox flow battery DCDC type equalization system and an electric energy equalization method thereof. The system comprises a DCDC equalizer, a PCS energy storage converter and a redox flow battery subsystem. The positive electrode of the flow battery subsystem A is connected with the input positive electrode In + of the DCDC equalizer after passing through the switching circuit Q1, the negative electrode of the flow battery subsystem A is connected with the output positive electrode Out + of the DCDC equalizer after converging with the positive electrode of the flow battery subsystem B and passing through the switching circuit Q2, and the negative electrode of the flow battery subsystem B is connected with the input negative electrode and the output negative electrode Bus-of the DCDC equalizer. A plurality of power loops are arranged in the DCDC equalizer, one end of an inductor on each power loop is connected with an output positive electrode Out +, and the other end of each inductor is connected with an input positive electrode In + and an input negative electrode In-through a switch tube. On the premise of not depending on the energy of the power grid, the electric quantity balance control among the flow battery subsystems is realized, so that the performance and the reliability of the whole system are improved.

Description

Technical Field

[0001] The present invention relates to the field of electric energy storage technology and system equipment, and in particular to an all-vanadium liquid flow battery DCDC type balancing system and an electric energy balancing method thereof. Background Art

[0002] At present, in the field of power energy storage technology, all-vanadium flow batteries have attracted much attention due to their advantages such as long life, large energy storage, high energy efficiency and good environmental adaptability. With the continuous improvement of the scale and complexity of all-vanadium flow battery systems, the imbalance problem between battery subsystems has gradually emerged, and this problem directly affects the performance and service life of the overall system. The battery balancing problem of all-vanadium flow batteries is mainly reflected in the concentration difference of the electrolyte and the voltage difference of the battery cells. The charging and discharging state of each battery cell cannot be kept consistent during long-term operation, which leads to uneven distribution of vanadium ion concentration in the electrolyte, which in turn causes the decline of battery performance and capacity loss. In addition, the voltage difference between battery cells will cause some battery subsystems to be overcharged or over-discharged, further exacerbating the risk of battery aging and damage. Although the existing ACDC equalizer can realize power balance control by charging the subsystem with lower SOC and discharging the subsystem with higher SOC, its balancing process needs to rely on the power supply of the power grid, resulting in high requirements for the external conditions required for its application. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a DCDC type balancing system for an all-vanadium liquid flow battery and an electric energy balancing method thereof, which realizes the electric energy balancing control between the liquid flow battery subsystems by connecting the three ports of the DCDC equalizer with the positive and negative poles of the two subsystems of the liquid flow battery without relying on the energy of the power grid, and cooperates with the multiple power circuit design, thereby improving the performance and reliability of the overall system.

[0004] The all-vanadium liquid flow battery DCDC type balancing system includes a DCDC balancer, a PCS energy storage converter, and two balanced liquid flow battery subsystems in the all-vanadium liquid flow battery; in the two balanced liquid flow battery subsystems, the positive electrode of the liquid flow battery subsystem A is connected to the input positive electrode In+ of the DCDC balancer through a switching circuit Q1, the negative electrode of the liquid flow battery subsystem A is connected to the output positive electrode Out+ of the DCDC balancer after merging with the positive electrode of the liquid flow battery subsystem B through a switching circuit Q2, and the negative electrode of the liquid flow battery subsystem B is connected to the input negative electrode and the output negative electrode Bus- of the DCDC balancer, wherein the DCDC balancer is provided with several heavy power circuits, and the power circuits include two switching tubes and an inductor, one end of the inductor is connected to the output positive electrode Out+, and the other end of the inductor is connected to the input positive electrode In+ and the input negative electrode In- through a switching tube. Each heavy power circuit balances the SOC between the liquid flow battery subsystems in an interlaced parallel manner.

[0005] Preferably, the power circuit includes two power circuits, a single power circuit and a double power circuit, wherein one end of the inductor L1 of the single power circuit is connected to the output positive pole Out+, and the other end is connected to the input positive pole In+ and the input negative pole In﹣ via switch tubes S1 and S2 respectively; one end of the inductor L2 of the single power circuit of the double power circuit is connected to the output positive pole Out+ after merging with L1, and the other end is connected to the input positive pole In+ and the input negative pole In﹣ via switch tubes S3 and S4 respectively.

[0006] Furthermore, the switching circuit Q1 is connected in series to the electrical connection line between the positive electrode of the liquid flow battery subsystem A and the input positive electrode In+ of the DCDC equalizer, and the switching circuit Q2 is connected in series to the electrical connection line between the negative electrode of the battery subsystem A, the positive electrode of the liquid flow battery subsystem B and the output positive electrode Out+ of the DCDC equalizer, and the switching circuit includes a switch and a resistor in parallel.

[0007] The controller input end of the all-vanadium liquid flow battery DCDC type equalization system is connected to the PCS energy storage converter and the liquid flow battery subsystems A and B, and the controller output end is connected to the DCDC equalizer; the controller integrates a microprocessor, a multi-channel signal channel module, a relay module, a 485 interface module, a DO / AO interface module, a display module, and a wireless data transmission module.

[0008] Furthermore, the voltage transformer and SOC sensor integrated on the PCS energy storage inverter and liquid flow battery subsystems A and B are connected to the microprocessor input via a multi-channel signal channel module, the microprocessor output is connected to the DO / AO interface module via a relay module, and the 485 interface module, display module, and wireless data transmission module are serially connected to the microprocessor. The microprocessor is connected to the PCS energy storage converter and the DCDC equalizer through the 485 interface module. The former is used to receive the charging condition signal of the PCS energy storage converter, and the latter is used to control the DCDC equalizer to switch the power supply current direction. The microprocessor determines charging or discharging through calculation, and the output signal is converted into a switch quantity signal or an analog signal for the switch of the switching circuit to close and open, and each switch tube to be turned on and off through the signal relay module. The switching circuit and each switch tube of the multiple power circuit are connected through the DO / AO interface module, and the execution signal is transmitted to realize automatic control. The display module is integrated with a liquid crystal display screen, which is used to display the PCS charging condition determined by the microprocessor, the received charge and discharge voltage and SOC value of the liquid flow battery subsystem A and B, the determined required charge and discharge condition, and the calculated charge and discharge time and progress and other parameters on site. The wireless data transmission module is used to upload the above parameter data to the remote host computer synchronously, and download and execute the instructions or programs sent by the remote host computer for parameter adjustment or system upgrade.

[0009] The electric energy balancing method of the all-vanadium liquid flow battery DCDC type balancing system realizes the electric energy balancing between the liquid flow battery subsystems A and B through the above-mentioned all-vanadium liquid flow battery DCDC type balancing system. The method for realizing electric energy balancing in the system includes the following steps: S1: PCS energy storage converter charges the flow battery subsystem; S2: The controller detects the difference SOCd between the SOCs of the liquid flow battery subsystem A and the liquid flow battery subsystem B in real time. When the SOCd is greater than the threshold value X%, it is determined that charge and discharge balance is required; S3: If the SOC of flow battery subsystem A is greater than the SOC of flow battery subsystem B, the controller determines that it is charging and controls the charging current of the DCDC balancer to flow from the input side to the output side; if the SOC of flow battery subsystem A is less than the SOC of flow battery subsystem B, the controller determines that it is discharging and controls the charging current in the DCDC balancer to flow from the output side to the input side; S4: During the charging and discharging process, the controller continuously detects the difference SOCd between the SOCs of the liquid flow battery subsystem A and the liquid flow battery subsystem B in real time. When the SOCd is less than the threshold value Y%, the controller controls the DCDC type equalizer to stop working and returns to step S2.

[0010] Furthermore, as described in step S3, the method in which the controller controls the current direction of the DCDC equalizer is that the controller controls the direction of the power supply current on the DCDC equalizer by controlling the closing / opening of the switch of the switching circuit Q1 / Q2, switching the flow from the output side to the input side and from the input side to the output side.

[0011] The beneficial effects of the all-vanadium liquid flow battery DCDC type balancing system and the electric energy balancing method thereof of the present invention are as follows: (1) The balancing control process does not rely on the energy of the grid; (2) The controller monitors the voltage and power parameters of the battery unit in real time and displays them on site and transmits the data remotely, ensuring that the operating status of the battery subsystem and the process of power balancing are clearly known; (3) Multiple power circuit design to reduce output ripple through interleaved control. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following is a further description of a DCDC type balancing system for an all-vanadium liquid flow battery and a method for balancing electric energy thereof in conjunction with the accompanying drawings: Figure 1 This is a wireframe diagram of the logic structure and connection principle of the embodiment 1 of the all-vanadium liquid flow battery DCDC type equalization system; Figure 2 It is a circuit diagram of the DCDC equalizer described in Example 2 of the DCDC type equalization system of the all-vanadium liquid flow battery; Figure 3This is a wireframe diagram of the logic structure and connection principle of the DCDC type equalization system embodiment 3 of the all-vanadium liquid flow battery; Figure 4 This is a wireframe diagram of the internal logic structure of the controller described in Example 5 of the all-vanadium liquid flow battery DCDC type equalization system; Figure 5 This is a step diagram of the implementation method of the electric energy balancing method of the all-vanadium liquid flow battery DCDC type balancing system; Figure 6 This is an operation flow chart of the electric energy balancing method of the all-vanadium liquid flow battery DCDC type balancing system.

[0013] In the figure: 1-DCDC equalizer, 2- PCS energy storage converter, 3- battery subsystem; 11- power circuit; 10-controller; 101-microprocessor, 102-multi-channel signal channel module, 103-relay module, 104-DO / AO interface module, 105-display module, 106-wireless data transmission module. DETAILED DESCRIPTION

[0014] In the present invention, unless otherwise clearly specified and limited, the terms "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 directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0015] In the description of the present invention, it should be understood that the terms "left", "right", "front", "back", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0016] The technical solution of the present invention is further described below with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0017] Example 1: Figure 1 , 2As shown, the all-vanadium liquid flow battery DCDC type balancing system includes a DCDC equalizer 1, a PCS energy storage converter 2, and two balanced liquid flow battery subsystems 3 in the all-vanadium liquid flow battery; in the two balanced liquid flow battery subsystems 3, the positive electrode of the liquid flow battery subsystem A is connected to the input positive electrode In+ of the DCDC equalizer 1 after passing through the switching circuit Q1, the negative electrode of the liquid flow battery subsystem A is connected to the output positive electrode Out+ of the DCDC equalizer 1 after merging with the positive electrode of the liquid flow battery subsystem B through the switching circuit Q2, and the negative electrode of the liquid flow battery subsystem B is connected to the input negative electrode and the output negative electrode Bus- of the DCDC equalizer 1, wherein the DCDC equalizer 1 is provided with a plurality of heavy power circuits 11, and the power circuit 11 includes two switching tubes and an inductor, one end of the inductor is connected to the output positive electrode Out+, and the other end of the inductor is connected to the input positive electrode In+ and the input negative electrode In- respectively through a switching tube. The switching circuit controls the direction of the supply current between the input and output of the DCDC equalizer, and cooperates with the heavy power loop to achieve SOC balance between the flow battery subsystems through staggered parallel connection.

[0018] Embodiment 2: The power circuit 11 of the all-vanadium liquid flow battery DCDC type equalization system includes two power circuits, a primary power circuit and a secondary power circuit. One end of the inductor L1 of the primary power circuit is connected to the output positive electrode Out+, and the other end is connected to the input positive electrode In+ and the input negative electrode In- through switch tubes S1 and S2 respectively; one end of the inductor L2 of the primary power circuit of the secondary power circuit is connected to the output positive electrode Out+ after merging with L1, and the other end is connected to the input positive electrode In+ and the input negative electrode In- through switch tubes S3 and S4 respectively. When the power of the liquid flow battery is large, multiple power circuits can be added. The switching circuit Q1 is connected in series to the electrical connection line between the positive electrode of the liquid flow battery subsystem A and the input positive electrode In+ of the DCDC equalizer 1, and the switching circuit Q2 is connected in series to the electrical connection line between the negative electrode of the battery subsystem A and the positive electrode of the liquid flow battery subsystem B and the output positive electrode Out+ of the DCDC equalizer 1. The switching circuit includes a parallel switch and a resistor. The two power circuits are equivalent circuits in terms of functional realization. During operation, the two power circuits are interleaved through the controller control to reduce the output ripple. When the power of the liquid flow battery is large, the required flow power between the liquid flow battery subsystems will increase. The DCDC type equalizer increases the number of multiple power circuits to meet the SOC balance between the liquid flow battery subsystems. The remaining structures and components are as described in Implementation 1 and will not be described again.

[0019] Example 3: Figure 3 , 4As shown, the input end of the controller 10 of the all-vanadium liquid flow battery DCDC type equalization system is connected to the PCS energy storage converter 2 and the liquid flow battery subsystems A and B, and the output end of the controller 10 is connected to the DCDC equalizer; the controller 10 is integrated with a microprocessor 101, a multi-channel signal channel module 102, a relay module 103, a DO / AO interface module 104, a display module 105, and a wireless data transmission module 106. The voltage transformer and SOC sensor integrated on the PCS energy storage converter 2 and the liquid flow battery subsystems A and B are connected to the input end of the microprocessor 101 through the multi-channel signal channel module, and the output end of the microprocessor 101 is connected to the DO / AO interface module 104 through the relay module 103 group, and the display module 105 and the wireless data transmission module 106 are serially connected to the microprocessor 101. The microprocessor is connected to the PCS energy storage converter and the DCDC equalizer through the 485 interface module. The former is used to receive the charging condition signal of the PCS energy storage converter, and the latter is used to control the DCDC equalizer to switch the power supply current direction. The microprocessor determines charging or discharging through calculation, and the output signal is converted into a switch quantity signal or analog signal for the switch of the switching circuit to close and open, and each switch tube to be turned on and off through the relay module. The DO / AO interface module connects the switching circuit and each switch tube of the multiple power circuit, and transmits the execution signal to realize automatic control. The display module is integrated with a liquid crystal display screen, which is used to display the PCS charging condition determined by the microprocessor, the charge and discharge voltage and SOC value of the received liquid flow battery subsystem A and B, the determined charge and discharge condition, and the calculated charge and discharge time and progress and other parameters on site. The wireless data transmission module is used to upload the above parameter data to the remote host computer synchronously, and download and execute the instructions or programs sent by the remote host computer for parameter adjustment or system upgrade. The remaining structures and components are as described in Implementation 1, and will not be described again.

[0020] Implementation method: Figure 5 , 6 As shown, the electric energy balancing method of the all-vanadium liquid flow battery DCDC type balancing system is implemented by the above-mentioned all-vanadium liquid flow battery DCDC type balancing system. The method for implementing electric energy balancing in the system includes the following steps: S1: PCS energy storage converter 2 charges the flow battery subsystem 3; S2: The controller detects the difference SOCd between the SOCs of the liquid flow battery subsystem A and the liquid flow battery subsystem B in real time. When the SOCd is greater than the threshold value X%, it is determined that charge and discharge balance is required; S3: If the SOC of flow battery subsystem A is greater than the SOC of flow battery subsystem B, the controller determines that it is charging, and controls the charging current of DCDC equalizer 1 to flow from the input side to the output side; if the SOC of flow battery subsystem A is less than the SOC of flow battery subsystem B, the controller determines that it is discharging, and controls the charging current in the DCDC equalizer to flow from the output side to the input side; S4: During the charging and discharging process, the controller continuously detects the difference SOCd between the SOC of the liquid flow battery subsystem A and the liquid flow battery subsystem B in real time. When SOCd is less than the threshold value Y%, the controller controls the DCDC type equalizer to stop working and returns to step S2. Further continue to detect the situation where the SOC between the two liquid flow battery subsystems continues to increase. Among them, the method described in step S3, in which the controller controls the current direction of the DCDC equalizer 1 is that the controller controls the direction of the power supply current on the DCDC equalizer by controlling the switch closing / opening of the switching circuit Q1 / Q2, switching the output side to the input side and the input side to the output side.

[0021] The all-vanadium liquid flow battery DCDC type balancing system and its electric energy balancing method, without relying on the energy of the power grid, realizes the power balancing control between the liquid flow battery subsystems through the connection method of the three ports of the DCDC equalizer with the positive and negative electrodes of the two subsystems of the liquid flow battery, and cooperates with the multiple power circuit design, thereby improving the performance and reliability of the overall system.

[0022] The above description shows the main features, basic principles, and advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments or embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, the above embodiments or embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A DCDC type balancing system for all-vanadium liquid flow batteries, characterized by: It comprises a DCDC equalizer (1), a PCS energy storage converter (2), and two balanced flow battery subsystems (3) in the all-vanadium flow battery; in the two balanced flow battery subsystems (3), the positive electrode of the flow battery subsystem A is connected to the input positive electrode In+ of the DCDC equalizer (1) through a switching circuit Q1, the negative electrode of the flow battery subsystem A is connected to the output positive electrode Out+ of the DCDC equalizer (1) through a switching circuit Q2 after merging with the positive electrode of the flow battery subsystem B, and the negative electrode of the flow battery subsystem B is connected to the input negative electrode and the output negative electrode Bus- of the DCDC equalizer (1), wherein: The DCDC equalizer (1) is provided with a plurality of heavy power circuits (11), wherein the power circuit (11) comprises two switch tubes and an inductor, wherein one end of the inductor is connected to the output positive electrode Out+, and the other end of the inductor is connected to the input positive electrode In+ and the input negative electrode In- through a switch tube. The heavy power circuits (11) are connected in parallel in an interlaced manner to balance the SOC between the liquid flow battery subsystems.

2. The all-vanadium liquid flow battery DCDC type equalization system according to claim 1 is characterized in that: The power circuit (11) comprises two power circuits, a primary power circuit and a secondary power circuit, wherein one end of the inductor L1 of the primary power circuit is connected to the output positive electrode Out+, and the other end is connected to the input positive electrode In+ and the input negative electrode In- through switch tubes S1 and S2, respectively; one end of the inductor L2 of the primary power circuit of the secondary power circuit is connected to the output positive electrode Out+ after merging with L1, and the other end is connected to the input positive electrode In+ and the input negative electrode In- through switch tubes S3 and S4, respectively.

3. The all-vanadium liquid flow battery DCDC type equalization system according to claim 2 is characterized by: The switching circuit Q1 is connected in series to the electrical connection line between the positive electrode of the liquid flow battery subsystem A and the input positive electrode In+ of the DCDC equalizer (1), and the switching circuit Q2 is connected in series to the electrical connection line between the negative electrode of the battery subsystem A and the positive electrode of the liquid flow battery subsystem B and the output positive electrode Out+ connected to the DCDC equalizer (1), and the switching circuit includes a switch and a resistor connected in parallel.

4. An energy balancing method for a DCDC type balancing system of an all-vanadium liquid flow battery, characterized by: The all-vanadium liquid flow battery DCDC type balancing system is the all-vanadium liquid flow battery DCDC type balancing system according to any one of claims 1 to 3, and the method for realizing electric energy balancing in the system comprises the following steps: S1: PCS energy storage converter (2) charges the flow battery subsystem (3); S2: The controller detects the difference SOCd between the SOCs of the liquid flow battery subsystem A and the liquid flow battery subsystem B in real time. When the SOCd is greater than the threshold value X%, it is determined that charge and discharge balance is required; S3: If the SOC of the flow battery subsystem A is greater than the SOC of the flow battery subsystem B, the controller determines that it is charging and controls the DCDC equalizer (1) so that the charging current flows from the input side to the output side; If the SOC of flow battery subsystem A is less than the SOC of flow battery subsystem B, the controller determines that it is discharging and controls the charging current in the DCDC equalizer to flow from the output side to the input side; S4: During the charging and discharging process, the controller continuously detects the difference SOCd between the SOCs of the liquid flow battery subsystem A and the liquid flow battery subsystem B in real time. When the SOCd is less than the threshold value Y%, the controller controls the DCDC type equalizer to stop working and returns to step S2.

5. The electric energy balancing method of the all-vanadium liquid flow battery DCDC type balancing system according to claim 4 is characterized by: In step S3, the method for the controller to control the current direction of the DCDC equalizer (1) is that the controller controls the direction of the power supply current on the DCDC equalizer by controlling the switch closing / opening of the switching circuit Q1 / Q2, and switches the flow from the output side to the input side and from the input side to the output side.

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