SOC balance switching system of liquid flow energy storage system

Abstract

The utility model relates to the field of liquid flow energy storage systems, in particular to an SOC (system on chip) balance switching system of a liquid flow energy storage system, which comprises an equalizer, N liquid flow subsystems to be equalized, N control loops, N controlled loops and N switching loops, and the N control loops are N groups of relay coils connected in parallel between a power supply end and a PLC (programmable logic controller) output end; the controlled loop comprises a relay normally-open contact, a relay normally-closed contact and N groups of direct-current contactor coils, the relay normally-open contact and the relay normally-closed contact are contacts corresponding to the relay coil on the control loop, each group of direct-current contactor coils comprises two direct-current contactor coils which are connected in parallel, and the N paths of switching loops are 2N contactor normally-open contacts. And the 2N contactor normally open contacts are connected between the equalizer and the positive and negative electrodes of the N to-be-equalized liquid flow subsystems connected in series, and N is a positive integer greater than 1. The system is suitable for various energy storage systems with different scales, and can solve the problem that the expansibility of current balance switching is limited.

Description

TECHNICAL FIELD

[0001] The utility model relates to liquid flow energy storage equalization field, concretely is a kind of SOC equalization switching system of liquid flow energy storage system. BACKGROUND

[0002] The main direction of energy storage technology development is large-scale, long life, low cost and environment-friendly. Liquid flow battery energy storage system has become one of the preferred technologies for large-scale energy storage technology due to its long service life, large energy storage scale, safety, no pollution, fast response speed and real-time monitoring of charge and discharge state. It has been successfully applied in many large-scale solar energy storage and wind power storage devices, large-scale emergency power supply systems and peak load shifting of power systems. SOC (state of charge) is a parameter that reflects the battery power state, and is the most direct basis for accurate control and management of battery system. It is also one of the most important parameters of liquid flow battery. In order to improve the performance and life of liquid flow battery, SOC equalization technology plays an important role in this regard. SOC equalization technology can be divided into active equalization technology and passive equalization technology. Active equalization technology is to dynamically adjust the power of the battery in the battery pack through active circuit or device to ensure that the SOC of all batteries is consistent. Passive equalization technology is to balance the power between batteries through resistance or other energy-consuming devices. However, whether it is active equalization technology or passive equalization technology, when the system detects a liquid cluster with uneven SOC, the equalization circuit and the liquid cluster form a loop, i.e. an equalization loop, through a certain switching method, and the equalization process can be carried out.

[0003] Most of the current equalization switching technologies face the problem of limited scalability. Although some equalization switching methods are suitable for small-scale energy storage systems, they may not be able to perform well in larger-scale energy storage systems and need to be redesigned. UTILITY MODEL CONTENT

[0004] The technical problem to be solved by the utility model is to provide a SOC equalization switching system for liquid flow energy storage system, which can be used in different scale energy storage systems without the need for redesign, thereby effectively solving the problem of limited scalability of most current equalization switching technologies.

[0005] To solve the technical problems, the utility model adopts the technical scheme: a kind of SOC equalization switching system of liquid flow energy storage system, including equalizer and N pending equalization liquid flow subsystem, still including N control loop, N controlled loop and N switching loop, N control loop is N groups of relay coil parallel between power supply end and PLC output end;Controlled loop includes relay normally open point, relay normally closed point and N groups of DC contactor coil, relay normally open point and relay normally closed point are the contact corresponding to relay coil on control loop, each group of relay coil includes one relay normally open point and N-1 relay normally closed points, one relay normally open point and N-1 relay normally closed points are connected on N controlled loop, and there is only one relay normally open point on each controlled loop;N groups of DC contactor coil are connected in series on controlled loop, each group of DC contactor coil includes two parallel DC contactor coils, N switching loop is 2N contactor normally open points corresponding to DC contactor coil on controlled loop, 2N contactor normally open points are connected between equalizer and the positive and negative pole of N series pending equalization liquid flow subsystem;The above N is greater than 1 positive integer.

[0006] Further, it further includes 2N feedback loops, 2N feedback loops are 2N contactor normally open points corresponding to DC contactor coil on controlled loop, and 2N contactor normally open points are connected between power supply end and PLC input end.

[0007] Further, the contactor normally open point is connected with the DC fuse through the busbar, and the DC fuse is connected with the positive pole or the negative pole of the liquid flow subsystem to be equalized.

[0008] Further, each group of relay coil on the control loop is an independent relay coil.

[0009] Further, each group of relay coil on the control loop is a plurality of parallel relay coils.

[0010] Further, N is an even number.

[0011] The utility model has the advantages that the utility model can adapt to energy storage systems of various scales, and when facing energy storage systems of different scales, the equalization switching system can be used, and only the number of corresponding circuits needs to be increased or reduced according to the number of liquid path clusters of the energy storage system, without adjusting the equalization switching method, thereby effectively solving the problem of limited expansion of the current equalization switching system. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is the circuit schematic diagram of the switching loop in embodiment 1.

[0013] Figure 2 It is the circuit schematic diagram of the control loop and controlled loop in embodiment 1.

[0014] Figure 3 Circuit diagram of the feedback loop in Example 1;

[0015] Figure 4 Circuit diagram of the switching loop in Example 2;

[0016] Figure 5 Circuit diagram of the control loop and the controlled loop in Example 2;

[0017] Figure 6 Circuit diagram of the feedback loop in Example 2;

[0018] Figure 7 Circuit diagram of the switching loop in Example 3;

[0019] Figure 8 Circuit diagram of the control loop and the controlled loop in Example 3;

[0020] Figure 9 Circuit diagram of the feedback loop in Example 3;

[0021] In the figure: FU1 to FU12 are DC fuses; KM1 to KM12 are DC contactors; KA1 to KA12 are intermediate relays. DETAILED DESCRIPTION

[0022] The utility model will be further explained in connection with the drawings and specific embodiments.

[0023] Example 1

[0024] This embodiment discloses a SOC equalization switching system of liquid flow energy storage system, and is suitable for 500kW / 2MWh vanadium redox flow energy storage switching system, such as Figure 1 、 2As shown, the system includes an equalizer and two liquid flow subsystems to be equalized, and further includes a two-way control loop, a two-way controlled loop and a two-way switching loop. The two-way control loop includes two independent relay coils KA1 and KA2 connected in parallel between a power supply end and a PLC output end. The controlled loop includes relay normally open points, relay normally closed points and two groups of DC contactor coils. The relay normally open points and the relay normally closed points are the contacts corresponding to the relay coils in the control loop, such as KA1-1 and KA1-2 which are the normally open points and the normally closed points corresponding to the relay coil KA1, and KA2-1 and KA2-2 which are the normally closed points and the normally open points corresponding to the relay coil KA2. The relay normally open points KA1-1 and KA2-1 and the relay normally closed points KA2-1 and KA2-2 are connected to the two-way controlled loop, and there is only one relay normally open point in each of the two-way controlled loop. The two groups of DC contactor coils are connected in series in the controlled loop, and each group of DC contactor coils includes two DC contactor coils connected in parallel, i.e. KM1 and KM3, and KM2 and KM4 in the figure. The two-way switching loop includes four contactor normally open points KM4-, KM3-, KM2- and KM1- corresponding to the DC contactor coils in the controlled loop, and the four contactor normally open points are connected between the equalizer and the positive and negative electrodes of the two series-connected liquid flow subsystems to be equalized.

[0025] As shown in Figure 3 , the system further includes a four-way feedback loop, which includes four contactor normally open points KM1, KM2, KM3 and KM4 corresponding to the DC contactor coils in the controlled loop, and the four contactor normally open points are connected between the power supply end and the PLC input end. In this embodiment, the power supply end is 24V provided by a battery management system (BMS) cabinet.

[0026] In this embodiment, the contactor normally open points are connected to DC fuses through busbars, and the DC fuses are connected to the positive or negative electrode of the liquid flow subsystem to be equalized. As shown in Figure 1 , the contactor normally open point KM4- is connected to the fuse FU5 through a busbar, the fuse FU5 is connected to the positive electrode of the subsystem 1, the contactor normally open point KM3- is connected to the fuse FU4 through a busbar, the fuse FU4 is connected to the negative electrode of the subsystem 1, the contactor normally open point KM2- is connected to the fuse FU2 through a busbar, the fuse FU2 is connected to the positive electrode of the subsystem 2, and the contactor normally open point KM1- is connected to the fuse FU1 through a busbar, and the fuse FU1 is connected to the negative electrode of the subsystem 2. In this embodiment, the subsystem 1 and the subsystem 2 are connected in series, i.e. the negative electrode of the subsystem 1 and the positive electrode of the subsystem 2 are connected together.

[0027] In this embodiment, the DC fuses are circuit protection devices, the busbars are connection devices, the DC contactors are circuit on-off control devices, and the relays are electric control devices. The SOC equalization switching is realized through the cooperation of these devices.

[0028] In this embodiment, the process of SOC equalization switching is: in the process of energy storage system discharging, taking the equalization of subsystem 1 as an example, the rest is the same. In the process of charging and discharging, when the SOC (i.e. state of charge) of subsystem 1 is lower than a predetermined value or is not in the equalization range, the equalization system will start to work. Figure 2 As shown in the figure, the 4th DO point output signal of the PLC module is output to the intermediate relay coil KA2, the 2-2 of the intermediate relay coil KA2 is a normally open point, and the 2-1 is a normally closed point, so when the intermediate relay coil KA2 is energized, the normally open point 2-1 is disconnected, and the normally closed point 2-2 is closed; and the 1-2 of the intermediate relay coil KA1 is a normally closed point, and the 1-1 is a normally open point, so at this time only the DC contactor coil KM2 and KM4 are connected, so that the contactor normally open points KM2- and KM4- are closed, and in Figure 1 We can know that at this time the equalizer and subsystem 1 form a loop, which charges subsystem 1, so that the state of charge of subsystem 1 of container 1 is in the equalization range, thereby achieving the purpose of equalization. Figure 3 For the feedback system, when the DC contactor coil KM2 and KM4 are connected, the normally open points KM2 and KM4 will also be connected, and the signal will be transmitted back to the DI point of the PLC module.

[0029] Embodiment 2

[0030] This embodiment discloses a SOC equalization switching system for a vanadium redox flow storage system, applicable to a 1MW / 4MWh all-vanadium redox flow storage switching system. It includes an equalizer and four flow subsystems to be equalized, as well as four control loops, four controlled loops, and four switching loops. The four control loops consist of four independent relay coils KA1, KA2, KA3, and KA4 connected in parallel between the power supply terminal and the PLC output terminal. The controlled loops include normally open and normally closed relay contacts and four sets of DC contactor coils. The normally open and normally closed relay contacts are the corresponding contacts of the relay coils in the control loops, such as KA1-1, KA1-2, and KA4. 1-3 and KA1-4 are one normally open contact and three normally closed contacts corresponding to relay coil KA1; KA2-1, KA2-2, KA2-3, and KA2-4 are the normally open contact and three normally closed contacts corresponding to relay coil KA2; KA3-1, KA3-2, KA3-3, and KA3-4 are the normally open contact and three normally closed contacts corresponding to relay coil KA3; KA4-1, KA4-2, KA4-3, and KA4-4 are the normally open contact and three normally closed contacts corresponding to relay coil KA4. The normally open and normally closed contacts of the relays are connected to the four controlled circuits, with only one normally open contact on each controlled circuit. Four sets of DC contactor coils are connected in series in the controlled circuit. Each set of DC contactor coils includes two DC contactor coils connected in parallel, namely KM1 and KM5, KM2 and KM6, KM3 and KM7, KM4 and KM8 in the figure. The four switching circuits are eight normally open contacts of the contactors corresponding to the DC contactor coils in the controlled circuit: KM8-, KM7-, KM6-, KM5-, KM4-, KM3-, KM2-, and KM1-. ​​The eight normally open contacts are connected between the equalizer and the positive and negative poles of the four series-connected fluid flow subsystems to be equalized.

[0031] like Figure 6 As shown, this system also includes eight feedback loops, which are eight normally open contacts (KM1, KM2, KM3, KM4, KM5, KM6, KM7, and KM8) corresponding to the DC contactor coils on the controlled circuit. These eight normally open contacts are connected between the power supply terminal and the PLC input terminal. In this embodiment, the power supply is 24V provided by the battery management system (BMS) cabinet.

[0032] In this embodiment, the normally open contact of the contactor is connected to a DC fuse via a busbar, and the DC fuse is connected to the positive or negative terminal of the fluid flow subsystem to be balanced. Specifically, as follows... Figure 4As shown, the contactor normally open point KM8 is connected to the fuse FU8 through the busbar, the fuse FU8 is connected to the positive pole of the subsystem 1, the contactor normally open point KM7 is connected to the fuse FU7 through the busbar, the fuse FU7 is connected to the negative pole of the subsystem 1. The contactor normally open point KM6 is connected to the fuse FU6 through the busbar, the fuse FU6 is connected to the positive pole of the subsystem 2, the contactor normally open point KM5 is connected to the fuse FU5 through the busbar, the fuse FU5 is connected to the negative pole of the subsystem 2. The contactor normally open point KM4 is connected to the fuse FU4 through the busbar, the fuse FU4 is connected to the positive pole of the subsystem 3, the contactor normally open point KM3 is connected to the fuse FU3 through the busbar, the fuse FU3 is connected to the negative pole of the subsystem 3, the contactor normally open point KM2 is connected to the fuse FU2 through the busbar, the fuse FU2 is connected to the positive pole of the subsystem 4, the contactor normally open point KM1 is connected to the fuse FU1 through the busbar, and the fuse FU1 is connected to the negative pole of the subsystem 4. In this embodiment, the subsystem 1, the subsystem 2, the subsystem 3 and the subsystem 4 are connected in series, that is, the negative pole of the subsystem 1 and the positive pole of the subsystem 2 are connected together, the negative pole of the subsystem 2 and the positive pole of the subsystem 3 are connected together, and the negative pole of the subsystem 3 and the positive pole of the subsystem 4 are connected together.

[0033] In this embodiment, the DC fuse is a circuit protection device, the busbar is a connecting device, the DC contactor is a circuit on-off control device, and the relay is an electric control device. The SOC balanced switching is realized through the cooperation of these devices.

[0034] Although the scale of this embodiment is doubled compared with the embodiment 1, the balanced loop needs to be increased to 4, and the balanced switching method does not need to be redesigned. In the process of charging and discharging, taking the balancing of the subsystem 2 as an example, the rest is the same. In the process of charging, when the SOC (state of charge) of the subsystem 2 is lower than a preset value or is not in the balanced range, the PLC module sends a signal to the relay coil KA3, and the relay coil KA3 is connected to the DC contactor coil KM3 / 7. When the relay coil KA3 is powered on, the normally closed points 3-1, 3-2 and 3-4 are disconnected, and the normally open point 3-3 is connected. At this time, only the DC contactor coil KM3 / 7 is connected, so that the contactor normally open points KM3- and KM7- are closed, and the contactor normally open points KM1-, KM2-, KM4- and KM5- are disconnected. At this time, the DC contactor coil KM3 / 7 is connected to the subsystem 2, and the subsystem 2 is charged, so that the state of charge of the subsystem 2 is in the balanced range, thereby achieving the purpose of balancing. Figure 5 As shown, the PLC module outputs an electrical signal to the intermediate relay coil KA3 through the 5th DO point, and the 3-1, 3-2 and 3-4 of the KA3 are normally closed points. Therefore, when the relay coil KA3 is powered on, the normally closed points 3-1, 3-2 and 3-4 are disconnected, and the normally open point 3-3 is connected. At this time, only the DC contactor coil KM3 / 7 is connected, so that the contactor normally open points KM3- and KM7- are closed, and the contactor normally open points KM1-, KM2-, KM4- and KM5- are disconnected. At this time, the DC contactor coil KM3 / 7 is connected to the subsystem 2, and the subsystem 2 is charged, so that the state of charge of the subsystem 2 is in the balanced range, thereby achieving the purpose of balancing. Figure 4 As shown, the PLC module outputs an electrical signal to the intermediate relay coil KA3 through the 5th DO point, and the 3-1, 3-2 and 3-4 of the KA3 are normally closed points. Therefore, when the relay coil KA3 is powered on, the normally closed points 3-1, 3-2 and 3-4 are disconnected, and the normally open point 3-3 is connected. At this time, only the DC contactor coil KM3 / 7 is connected, so that the contactor normally open points KM3- and KM7- are closed, and the contactor normally open points KM1-, KM2-, KM4- and KM5- are disconnected. At this time, the DC contactor coil KM3 / 7 is connected to the subsystem 2, and the subsystem 2 is charged, so that the state of charge of the subsystem 2 is in the balanced range, thereby achieving the purpose of balancing. Figure 6 As feedback, when the DC contactor coil KM3 and KM7 are connected, the normally open points KM3 and KM7 are also closed, and the signal is transmitted back to the DI point of the PLC module.

[0035] Example 3

[0036] This embodiment discloses a SOC equalization switching system for a vanadium redox flow storage system, applicable to a 1.5MW / 6MWh all-vanadium redox flow storage switching system. For example... Figure 7 , 8 As shown, it includes an equalizer and six fluid flow subsystems to be equalized, as well as six control loops, six controlled loops, and six switching loops. The six control loops consist of six sets of relay coils connected in parallel between the power supply terminal and the PLC output terminal; each set of relay coils includes two relay coils connected in parallel, i.e. Figure 8 KA1 and KA2, KA3 and KA4, KA5 and KA6, KA7 and KA8, KA9 and KA10, KA11 and KA12.

[0037] The controlled circuit includes normally open and normally closed relay contacts and six sets of DC contactor coils. The normally open and normally closed relay contacts are the contacts of the relay coils in the control circuit. For example, KA1-1, KA1-2, and KA1-3 are one normally open and two normally closed contacts corresponding to relay coil KA1; KA2-1, KA2-2, and KA2-3 are three normally closed contacts corresponding to relay coil KA2; KA3-1, KA3-2, and KA3-3 are normally open and two normally closed contacts corresponding to relay coil KA3; and KA4-1, KA4-2, and KA4-3 are three normally closed contacts corresponding to relay coil KA4. The others are the same and will not be repeated here. The normally open and normally closed relay contacts are connected to the six controlled circuits, with only one normally open relay contact on each controlled circuit. Six sets of DC contactor coils are connected in series in the controlled circuit. Each set of DC contactor coils includes two DC contactor coils connected in parallel, namely KM1 and KM7, KM2 and KM8, KM3 and KM9, KM4 and KM10, KM5 and KM11, KM6 and KM12 in the figure. The six switching circuits have 12 normally open contacts corresponding to the DC contactor coils in the controlled circuit: KM12-, KM11-, KM10-, KM9-, KM8-, KM7-, KM6-, KM5-, KM4-, KM3-, KM2-, and KM1-. ​​The 12 normally open contacts are connected between the equalizer and the positive and negative poles of the six series-connected fluid flow subsystems to be equalized.

[0038] like Figure 6 As shown, this system also includes 12 feedback loops, which are 12 normally open contacts KM1, KM2, KM3, KM4, KM5, KM6, KM7, KM8, KM9, KM10, KM11, and KM12 corresponding to the DC contactor coils on the controlled circuit. The 12 normally open contacts are connected between the power supply terminal and the PLC input terminal.

[0039] In this embodiment, the normally open contact of the contactor is connected to a DC fuse via a busbar, and the DC fuse is connected to the positive or negative terminal of the fluid flow subsystem to be balanced. Specifically, as follows... Figure 7 As shown, the normally open contact KM12 of the contactor is connected to the fuse FU12 via the busbar. The fuse FU12 is connected to the positive terminal of subsystem 1. The normally open contact KM11 of the contactor is connected to the fuse FU11 via the busbar. The fuse FU11 is connected to the negative terminal of subsystem 1. The same applies here, and will not be repeated.

[0040] In this embodiment, the DC fuse is a circuit protection device, the busbar is a connection device, the DC contactor is a circuit on / off control device, and the relay is an electrical control device. The coordination of these devices achieves SOC balanced switching.

[0041] In this embodiment, the selection of devices is the same as in Embodiments 1 and 2, the equalization method remains unchanged, and the number of equalization loops is increased to 6. During the discharge process of the energy storage system, taking the equalization of subsystem 4 as an example, the rest are handled similarly. During the discharge process, when the SOC (State of Charge) of subsystem 4 is lower than a predetermined value or is not within the equalization range, such as... Figure 8 The PLC module shown outputs an electrical signal from point DO (position 5) to intermediate relays KA5 and KA6. KA5 has normally closed contacts 5-1 and 5-2, and normally open contact 5-3; KA6 has normally closed contacts 6-1, 6-2, and 6-3. Therefore, when relays KA5 and KA6 are energized, normally closed contacts 5-1, 5-2, 6-1, 6-2, and 6-3 are open, and normally open contact 5-3 is closed. At this time, only the DC contactor coil KM3 / 9 is conducting, causing the normally open contacts KM3- and KM9- to close. Figure 7 We can see that at this time, the equalizer and subsystem 4 form a loop, charging the subsystem and keeping its charge state within the equalization range, thus achieving the purpose of equalization. Figure 9 As a feedback system, when DC contactors KM3 and KM9 are turned on, they will transmit signals back to the DI point of the PLC module.

[0042] The SOC equalization switching system described in this utility model can adapt to energy storage systems of various sizes. When facing energy storage systems of different sizes, this equalization switching system can be used. It is only necessary to increase or decrease the number of equalization circuits and feedback circuits according to the number of liquid circuit clusters in the energy storage system. There is no need to adjust the equalization switching logic, thereby effectively solving the problem of limited scalability of the current equalization switching system.

[0043] The above description is only the basic principle and preferred embodiment of this utility model. Any improvements and substitutions made by those skilled in the art based on this utility model shall fall within the protection scope of this utility model.

Claims

1. A SOC equalization switching system of a liquid flow energy storage system, comprising an equalizer and N liquid flow subsystems to be equalized, characterized in that: The application also comprises N control circuits, N controlled circuits and N switching circuits, the N control circuits are N groups of relay coils connected in parallel between a power supply end and a PLC output end; the controlled circuits comprise relay normally open points, relay normally closed points and N groups of DC contactor coils, the relay normally open points and the relay normally closed points are contacts corresponding to the relay coils on the control circuits, each group of relay coils comprises one relay normally open point and N-1 relay normally closed points, one relay normally open point and N-1 relay normally closed points are connected on the N controlled circuits, and there is only one relay normally open point on each controlled circuit; the N groups of DC contactor coils are connected in series on the controlled circuits, each group of DC contactor coils comprises two parallel DC contactor coils, the N switching circuits are 2N contactor normally open points corresponding to the DC contactor coils on the controlled circuits, and the 2N contactor normally open points are connected between the balancer and the positive and negative poles of the N series liquid flow subsystems to be balanced; the N is a positive integer greater than 1.

2. The SOC equalization switching system of liquid flow energy storage system of claim 1, wherein: The application also comprises 2N feedback circuits, the 2N feedback circuits are 2N contactor normally open points corresponding to the DC contactor coils on the controlled circuits, and the 2N contactor normally open points are connected between the power supply end and the PLC input end.

3. The SOC equalization switching system of flow-based energy storage system of claim 1, wherein: The contactor normally open points are connected to the DC fuses through busbars, and the DC fuses are connected to the positive or negative poles of the liquid flow subsystems to be balanced.

4. The SOC equalization switching system of flow-based energy storage system of claim 1, wherein: Each group of relay coils on the control circuits is one independent relay coil.

5. The SOC equalization switching system of flow-based energy storage system of claim 1, wherein: Each group of relay coils on the control circuits is a plurality of parallel relay coils.

6. The SOC balancing switch system of flow energy storage system of claim 1, wherein: The N is an even number.

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