Vanadium battery energy storage and boosting all-in-one machine

Abstract

The utility model relates to a vanadium battery energy storage and boosting all-in-one machine, which belongs to the technical field of vanadium batteries and comprises a movable direct-current converter, a plurality of bidirectional converters and a transformer. The plurality of bidirectional converters are connected with the plurality of vanadium batteries through the plurality of direct-current power switches and are connected with the transformer through a low-voltage bus, and the transformer is connected to a power grid; when the vanadium battery is in a low-voltage state, the corresponding direct-current power switch of the vanadium battery is switched off, the movable direct-current converter is connected with the corresponding direct-current power switch in parallel through the parallel interface, and alternating-current voltage input by a power grid is converted into battery activation voltage through the transformer, the corresponding bidirectional converter and the movable direct-current converter. According to the utility model, a common charging voltage is converted into a battery activation voltage required by the vanadium battery by adopting the accessed mobile direct-current converter, and the mobile direct-current converter can be moved out after starting, so that the running efficiency of the energy storage system is prevented from being reduced while zero-voltage starting is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of vanadium batteries, in particular to a vanadium battery energy storage and voltage boosting integrated machine. Background Art

[0002] All-vanadium liquid flow battery is a new energy storage technology with relatively young technology. It is particularly suitable for applications with high safety requirements and the need for flexible adjustment of energy storage capacity. Its basic principle is: vanadium ion solutions with different valence states are stored in the positive and negative electrolyte tanks respectively, and the positive and negative electrolytes are provided to the battery module separately through an external pump body. The positive and negative electrolytes are separated by a diaphragm inside the battery. After the redox reaction occurs, each returns to its own storage tank, and this cycle continues to complete the mutual conversion of electrical energy and chemical energy.

[0003] The voltage of the all-vanadium liquid flow battery does not match the power grid. When the battery is discharging, it needs to be boosted before it can be input into the power grid. When charging, the voltage input from the power grid needs to be stepped down. Therefore, it needs to be connected to the power grid through a PCS (Power Conversion System, bidirectional energy storage inverter) to complete the charging and discharging work. The voltage of the all-vanadium liquid flow battery is lower than the minimum voltage during normal operation. For example, when the electrolyte is in the initial factory state, the positive and negative tanks are in the same state, the electrolyte has no power, or the electrolyte needs to be replenished, mixed, and other maintenance. At this time, the normal operating voltage of the vanadium battery exceeds the operating voltage range of the bidirectional inverter. At this time, if conventional PCS is used for charging, a large current will be generated, causing the equipment to trip.

[0004] Therefore, it is urgent to propose an energy storage inverter that can meet the zero-voltage starting requirements of all-vanadium batteries. Utility Model Content

[0005] In view of this, it is necessary to provide a vanadium battery energy storage and boosting integrated machine to solve the technical problem that the existing energy storage converter cannot perform zero-voltage start on the vanadium battery.

[0006] In order to solve the above problems, the utility model provides a vanadium battery energy storage and boosting integrated machine, including a mobile DC converter, a plurality of bidirectional converters and a transformer;

[0007] A plurality of the bidirectional converters are connected to a plurality of vanadium batteries through a plurality of DC power switches and connected to the transformer through a low-voltage bus, and the transformer is connected to a power grid;

[0008] When the vanadium battery is in a low voltage state, the corresponding DC power switch of the vanadium battery is disconnected, and the mobile DC converter is connected in parallel with the corresponding DC power switch through a parallel interface, and the AC voltage input from the power grid is converted into a battery activation voltage through the transformer, the corresponding bidirectional converter and the mobile DC converter.

[0009] In a possible implementation, the bidirectional converter includes an LC filter and an inverter;

[0010] The LC filter is connected to the inverter and the transformer respectively, and the inverter is connected to the DC power switch;

[0011] The inverter is used to convert direct current into alternating current or to convert alternating current into direct current;

[0012] The LC filter is used to filter out harmonics generated by the inverter.

[0013] In a possible implementation, the parallel interface includes a first interface and a second interface, and the mobile DC converter includes a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a third insulated gate bipolar transistor, a fourth insulated gate bipolar transistor, a first inductor, and a first capacitor;

[0014] The collector of the first insulated gate bipolar transistor is connected to the positive electrode of the first interface and the first end of the first capacitor, the emitter of the first insulated gate bipolar transistor is connected to the first end of the first inductor and the collector of the second insulated gate bipolar transistor, the emitter of the second insulated gate bipolar transistor T2 is connected to the negative electrode of the first interface, the second end of the first capacitor, the emitter of the fourth insulated gate bipolar transistor and the negative electrode of the second interface, the collector of the fourth insulated gate bipolar transistor is connected to the second end of the first inductor and the emitter of the third insulated gate bipolar transistor, and the collector of the third insulated gate bipolar transistor is connected to the positive electrode of the second interface.

[0015] In a possible implementation, the inverter is an E-type three-level inverter, which is composed of twelve insulated gate bipolar transistors, six diodes and two capacitors.

[0016] In a possible implementation, the LC filter includes second to seventh inductors, second to fourth capacitors, and first to third resistors;

[0017] The first end of the second inductor, the first end of the third inductor L3 and the first end of the fourth inductor are connected to the voltage input terminal of the inverter, the second end of the second inductor is connected to the first end of the fifth inductor and the first end of the second capacitor, the second end of the third inductor L3 is connected to the first end of the sixth inductor and the first end of the third capacitor, the first end of the fourth inductor is connected to the first end of the seventh inductor and the first end of the fourth capacitor, the second end of the second capacitor is connected to the first end of the first resistor, the second end of the third capacitor is connected to the first end of the second resistor, the second end of the fourth capacitor is connected to the first end of the third resistor, the second end of the first resistor is connected to the second end of the second resistor and the second end of the third resistor, and the second end of the fifth inductor, the second end of the sixth inductor and the second end of the seventh inductor are connected to the transformer as three-phase ends.

[0018] In a possible implementation, an AC electromagnetic compatibility filter is further provided between the transformer and the bidirectional converter;

[0019] The AC electromagnetic compatibility filter is used to filter out electromagnetic interference and electric spark interference on the AC side of the bidirectional converter.

[0020] In a possible implementation, a lightning arrester is provided between the AC electromagnetic compatibility filter and the transformer and between the vanadium battery and the corresponding DC power switch.

[0021] In a possible implementation manner, an AC contactor and an AC circuit breaker are provided between the AC electromagnetic compatibility filter and the bidirectional converter.

[0022] In a possible implementation, a DC electromagnetic compatibility filter is provided between the bidirectional converter and the corresponding DC power switch;

[0023] The DC electromagnetic compatibility filter is used to filter out electromagnetic interference and electric spark interference on the DC side of the bidirectional converter.

[0024] In a possible implementation, a load switch and a DC fuse are provided between the corresponding DC power switch and the vanadium battery.

[0025] The beneficial effects of the utility model are as follows: the vanadium battery energy storage and boosting integrated machine provided by the utility model includes a mobile DC converter, a plurality of bidirectional converters and a transformer. When the vanadium battery is in a low voltage state, the corresponding DC power switch of the vanadium battery is controlled to be disconnected, the mobile DC converter is connected in parallel with the corresponding DC power switch through a parallel interface, the high voltage AC input from the power grid is stepped down through the transformer, the corresponding bidirectional converter is used to convert the stepped-down AC power into DC power, and then the connected mobile DC converter is used to convert the DC power into the battery activation voltage required by the vanadium battery, the vanadium battery is charged through the battery activation voltage, and the zero voltage start of the vanadium battery is realized. After starting, the mobile DC converter can be removed to avoid the mobile DC converter working for a long time and reducing the operation efficiency of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the working principle of an embodiment of a vanadium battery energy storage and boosting integrated device provided by the utility model;

[0027] Figure 2 A schematic diagram of the circuit structure of an embodiment of a bidirectional converter in a vanadium battery energy storage and boosting integrated machine provided by the utility model;

[0028] Figure 3 The present invention provides a schematic diagram of the circuit structure of a mobile DC converter in a vanadium battery energy storage and boosting integrated machine according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0030] Reference Figure 1 , Figure 1 A schematic diagram of the working principle of an embodiment of a vanadium battery energy storage and boosting integrated machine provided by the utility model; the utility model discloses a vanadium battery energy storage and boosting integrated machine, including a mobile DC converter 70, a plurality of bidirectional converters 10 and a transformer 20;

[0031] A plurality of bidirectional converters 10 are connected to a plurality of vanadium batteries through a plurality of DC power switches K3 and connected to a transformer 20 through a low-voltage bus, and the transformer 20 is connected to a power grid;

[0032] When the vanadium battery is in a low voltage state, the corresponding DC power switch K3 of the vanadium battery is disconnected, and the mobile DC converter 70 is connected in parallel with the corresponding DC power switch K3 through the parallel interface 80, and the AC voltage input from the power grid is converted into a battery activation voltage through the transformer 20, the corresponding bidirectional converter 10 and the mobile DC converter 70.

[0033] It should be noted that in the embodiment of the utility model, the vanadium battery energy storage and boosting integrated machine is a container-type structure, and the transformer 20 can adopt a 35kv dry-type main transformer, which adopts an integrated design, has a high degree of system integration, and is highly adaptable to the environment, effectively reducing the workload of on-site installation, commissioning, and later maintenance. During implementation, the high-voltage side of the dry-type main transformer is connected to the power grid, and the low-voltage side divides a plurality of AC three-phase windings to the AC side of a plurality of bidirectional converters 10. The inverter 110 of the bidirectional converter 10 converts the AC into DC to charge the vanadium battery or converts the DC power discharged by the vanadium battery into AC and then transmits it to the power grid. When the working voltage of the vanadium battery is lower than the lowest voltage that the bidirectional converter 10 can output (i.e., the low-voltage state), the vanadium The DC power switch K3 of the battery connects the mobile DC converter 70, and converts the DC voltage output by the bidirectional converter 10 into the adaptation voltage of the vanadium battery through the mobile DC converter 70 (because the voltage conversion range required for zero-voltage starting of the vanadium battery is relatively wide and the voltage value is relatively low, it is easier to achieve using a DC converter), and the mobile DC converter 70 is only used when the vanadium battery is started at zero voltage. After completing the zero-voltage starting of the vanadium battery, the mobile DC converter 70 can be withdrawn, and the corresponding DC power switch K3 is closed to restore the connection between the bidirectional converter 10 and the vanadium battery to perform normal charging and discharging operations, thereby avoiding the long-term connection of the mobile DC converter 70, which leads to higher energy consumption and lower efficiency of the entire energy storage system.

[0034] Compared with the prior art, the vanadium battery energy storage and boosting integrated machine provided by the utility model includes a mobile DC converter 70, a plurality of bidirectional converters 10 and a transformer 20. When the vanadium battery is in a low voltage state, the corresponding DC power switch K3 of the vanadium battery is controlled to be disconnected, and the mobile DC converter 70 is connected in parallel with the corresponding DC power switch K3 through a parallel interface 80. The high-voltage AC input from the power grid is stepped down through the transformer 20, and the stepped-down AC power is converted into DC power by the corresponding bidirectional converter 10. The connected mobile DC converter 70 is then used to convert the DC power into the battery activation voltage required by the vanadium battery. The vanadium battery is charged by the battery activation voltage to achieve zero-voltage start-up of the vanadium battery. After starting, the mobile DC converter 70 can be removed to avoid the mobile DC converter 70 working for a long time to reduce the operating efficiency of the energy storage system.

[0035] Since the bidirectional converter 10 is a voltage source converter based on an insulated gate bipolar transistor, and voltage conversion is mainly achieved through high-frequency switching, which will generate corresponding switching frequency harmonics, the bidirectional converter 10 provided by the utility model includes an LC filter 120 and an inverter 110;

[0036] The LC filter 120 is connected to the inverter 110 and the transformer 20 respectively, and the inverter 110 is connected to the DC power switch K3;

[0037] The inverter 110 is used to convert direct current into alternating current or to convert alternating current into direct current;

[0038] The LC filter 120 is used to filter out harmonics generated by the inverter 110 .

[0039] Reference Figure 2 , Figure 2 The circuit structure diagram of an embodiment of a bidirectional converter in a vanadium battery energy storage and boosting integrated machine provided by the utility model. In a specific implementation, the LC filter 120 includes a second inductor L2 to a seventh inductor L7, a second capacitor C2 to a fourth capacitor C4 and a first resistor R1 to a third resistor R3;

[0040] The first end of the second inductor L2, the first end of the third inductor L3 and the first end of the fourth inductor L4 are connected to the voltage input terminal of the inverter 110, the second end of the second inductor L2 is connected to the first end of the fifth inductor L5 and the first end of the second capacitor C2, the second end of the third inductor L3 is connected to the first end of the sixth inductor L6 and the first end of the third capacitor C3, the first end of the fourth inductor L4 is connected to the first end of the seventh inductor L7 and the first end of the fourth capacitor C4, the second end of the second capacitor C2 is connected to the first end of the first resistor R1, the second end of the third capacitor C3 is connected to the first end of the second resistor R2, the second end of the fourth capacitor C4 is connected to the first end of the third resistor R3, the second end of the first resistor R1 is connected to the second end of the second resistor R2 and the second end of the third resistor R3, and the second end of the fifth inductor L5, the second end of the sixth inductor L6 and the second end of the seventh inductor L7 are connected to the transformer 20 as three-phase ends.

[0041] Reference Figure 3 , Figure 3 A circuit structure diagram of an embodiment of a mobile DC converter in a vanadium battery energy storage and boosting integrated machine provided by the utility model. In the embodiment of the utility model, the parallel interface 80 includes a first interface 810 and a second interface 820, and the mobile DC converter 70 includes a first insulated gate bipolar transistor T1, a second insulated gate bipolar transistor T2, a third insulated gate bipolar transistor T3, a fourth insulated gate bipolar transistor T4, a first inductor L1 and a first capacitor C1;

[0042] The collector of the first insulated gate bipolar transistor T1 is connected to the positive electrode of the first interface 810 and the first end of the first capacitor C1, the emitter of the first insulated gate bipolar transistor T1 is connected to the first end of the first inductor L1 and the collector of the second insulated gate bipolar transistor T2, the emitter of the second insulated gate bipolar transistor T2 is connected to the negative electrode of the first interface 810, the second end of the first capacitor C1, the emitter of the fourth insulated gate bipolar transistor T4 and the negative electrode of the second interface 820, the collector of the fourth insulated gate bipolar transistor T4 is connected to the second end of the first inductor L1 and the emitter of the third insulated gate bipolar transistor T3, and the collector of the third insulated gate bipolar transistor T3 is connected to the positive electrode of the second interface 820.

[0043] It should be noted that in the embodiment of the utility model, the mobile DC converter 70 adopts a modular design and is equipped with an easy-to-operate interface. The easy-to-operate interface can be a plug-in power aviation plug or a trolley-type contact arm, which is convenient for connection with the above-mentioned parallel interface. The mobile DC converter 70 can be equipped with an electric trolley or rollers, which can be freely moved in the energy storage power station. When a vanadium battery is in a low voltage state and needs to be activated, the mobile DC converter 70 is moved to the vicinity of the vanadium battery, and connected to the parallel interface 80 through the easy-to-operate interface. 0 is connected to the loop, and the corresponding DC power switch K3 is disconnected at this time. The mobile DC converter 70 converts the DC power output by the bidirectional converter 10 into the battery activation voltage required by the vanadium battery, and charges the vanadium battery through the battery activation voltage. When the vanadium battery is out of the low voltage state (that is, the bidirectional converter 10 can provide the charging voltage alone), the mobile DC converter 70 is disconnected, the DC power switch K3 is closed, and the vanadium battery resumes normal charging and discharging operation. The mobile DC converter 70 can be moved to other vanadium batteries that need to be activated to continue the battery activation work.

[0044] It can be understood that in the embodiment of the utility model, during the battery activation process, since the internal resistance of the vanadium battery is only 50-80 milliohms, which is relatively small, the output voltage of the portable DC converter 70 in the initial stage is not easy to be too large, so as to avoid current runaway and battery overcurrent. Although the portable DC converter 70 can adopt the traditional voltage and current dual closed-loop control, the current can be gradually increased steplessly from small to large, and the processing method can be activated by the current ramp starting method or the step current starting method.

[0045] In some embodiments of the present invention, the inverter 110 is an E-type three-level inverter, which is composed of twelve insulated gate bipolar transistors, six diodes and two capacitors.

[0046] For specific implementation, please refer to Figure 2Specific electrical structure diagram of the bidirectional converter, the inverter 110 includes 12 insulated gate bipolar transistors T5 to T14, six diodes D1 to D6, and a fifth capacitor and a sixth capacitor.

[0047] It should be noted that the E-type three-level inverter is a bidirectional inverter 110, which can convert the input AC into DC during charging, and can convert the DC output of the vanadium battery into AC during discharging, which is achieved by controlling the switching frequency of the insulated gate bipolar transistor through pulse width modulation. The electrical connection between the inverter 110 and the LC filter 120 can be referred to Figure 2 .

[0048] In order to filter out the high-frequency harmonic interference of the AC measurement of the bidirectional converter 10, the utility model further provides an AC electromagnetic compatibility filter 30 between the transformer 20 and the bidirectional converter 10;

[0049] The AC electromagnetic compatibility filter 30 is used to filter out electromagnetic interference and electric spark interference on the AC side of the bidirectional converter 10 .

[0050] In some embodiments of the present invention, since the vanadium battery energy storage and boosting integrated machine mostly adopts a container-type structure, there is a possibility of outdoor work and it may be damaged when encountering lightning. Therefore, the vanadium battery energy storage and boosting integrated machine provided by the present invention is provided with a lightning arrester between the AC electromagnetic compatibility filter and the transformer 20 and between the vanadium battery and the corresponding DC power switch K3, such as Figure 1 As shown, it includes an AC lightning arrester 50 and a DC lightning arrester 60 .

[0051] In some embodiments of the present invention, an AC contactor K1 and an AC circuit breaker K2 are provided between the AC electromagnetic compatibility filter 30 and the bidirectional converter 10 .

[0052] It can be understood that the AC contactor K1 is used to control the on and off of the AC side of the bidirectional converter 10, and the AC circuit breaker K2 is used to cut off the AC line in time when the vanadium battery energy storage booster fails.

[0053] It can be understood that in the embodiment of the utility model, the DC side of the bidirectional converter 10 may also have high-frequency harmonic interference, so a DC electromagnetic compatibility filter 40 is provided between the bidirectional converter 10 and the corresponding DC power switch K3;

[0054] The DC electromagnetic compatibility filter 40 is used to filter out strong electromagnetic interference and electric spark interference on the DC side of the bidirectional converter 10 .

[0055] It should be noted that since the DC side of the bidirectional converter 10 is connected to the vanadium battery, it can directly affect the safety of the vanadium battery. Therefore, the utility model is provided with a load switch K4 and DC fuses F1 and F2 between the corresponding DC power switch K3 and the vanadium battery to ensure the safety of the DC side of the bidirectional converter 10.

[0056] It should be noted that in the embodiment of the utility model, when the vanadium battery is discharged, the bidirectional converter 10 can flexibly control the output voltage phase and amplitude through pulse width modulation, and use the phase and amplitude difference between the output voltage and the grid voltage to form active and reactive currents on the filter inductor of the output side LC filter 120, thereby achieving the purpose of controlling the four-quadrant operation of the active and reactive power injected into the grid.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention.

Claims

1. A vanadium battery energy storage and boosting integrated machine, characterized in that: Includes mobile DC converters, multiple bidirectional converters and transformers; A plurality of the bidirectional converters are connected to a plurality of vanadium batteries through a plurality of DC power switches and connected to the transformer through a low-voltage bus, and the transformer is connected to a power grid; When the vanadium battery is in a low voltage state, the corresponding DC power switch of the vanadium battery is disconnected, and the mobile DC converter is connected in parallel with the corresponding DC power switch through a parallel interface, and the AC voltage input from the power grid is converted into a battery activation voltage through the transformer, the corresponding bidirectional converter and the mobile DC converter; The parallel interface includes a first interface and a second interface, and the mobile DC converter includes a first insulated gate bipolar transistor, a second insulated gate bipolar transistor, a third insulated gate bipolar transistor, a fourth insulated gate bipolar transistor, a first inductor and a first capacitor; The collector of the first insulated gate bipolar transistor is connected to the positive electrode of the first interface and the first end of the first capacitor, the emitter of the first insulated gate bipolar transistor is connected to the first end of the first inductor and the collector of the second insulated gate bipolar transistor, the emitter of the second insulated gate bipolar transistor is connected to the negative electrode of the first interface, the second end of the first capacitor, the emitter of the fourth insulated gate bipolar transistor and the negative electrode of the second interface, the collector of the fourth insulated gate bipolar transistor is connected to the second end of the first inductor and the emitter of the third insulated gate bipolar transistor, and the collector of the third insulated gate bipolar transistor is connected to the positive electrode of the second interface.

2. The vanadium battery energy storage and boosting integrated machine according to claim 1 is characterized in that: The bidirectional converter includes an LC filter and an inverter; The LC filter is connected to the inverter and the transformer respectively, and the inverter is connected to the DC power switch; The inverter is used to convert direct current into alternating current or to convert alternating current into direct current; The LC filter is used to filter out harmonics generated by the inverter.

3. The vanadium battery energy storage and boosting integrated machine according to claim 2 is characterized in that: The inverter is an E-type three-level inverter, which is composed of twelve insulated gate bipolar transistors, six diodes and two capacitors.

4. The vanadium battery energy storage and boosting integrated machine according to claim 3 is characterized in that: The LC filter includes second to seventh inductors, second to fourth capacitors, and first to third resistors; The first end of the second inductor, the first end of the third inductor and the first end of the fourth inductor are connected to the voltage input terminal of the inverter, the second end of the second inductor is connected to the first end of the fifth inductor and the first end of the second capacitor, the second end of the third inductor is connected to the first end of the sixth inductor and the first end of the third capacitor, the first end of the fourth inductor is connected to the first end of the seventh inductor and the first end of the fourth capacitor, the second end of the second capacitor is connected to the first end of the first resistor, the second end of the third capacitor is connected to the first end of the second resistor, the second end of the fourth capacitor is connected to the first end of the third resistor, the second end of the first resistor is connected to the second end of the second resistor and the second end of the third resistor, and the second end of the fifth inductor, the second end of the sixth inductor and the second end of the seventh inductor are connected to the transformer as three-phase ends.

5. The vanadium battery energy storage and boosting integrated machine according to claim 1, characterized in that: An AC electromagnetic compatibility filter is also provided between the transformer and the bidirectional converter; The AC electromagnetic compatibility filter is used to filter out electromagnetic interference and electric spark interference on the AC side of the bidirectional converter.

6. The vanadium battery energy storage and boosting integrated machine according to claim 5, characterized in that: A lightning arrester is provided between the AC electromagnetic compatibility filter and the transformer and between the vanadium battery and the corresponding DC power switch.

7. The vanadium battery energy storage and boosting integrated machine according to claim 6, characterized in that: An AC contactor and an AC circuit breaker are arranged between the AC electromagnetic compatibility filter and the bidirectional converter.

8. The vanadium battery energy storage and boosting integrated machine according to claim 1, characterized in that: A DC electromagnetic compatibility filter is provided between the bidirectional converter and the corresponding DC power switch; The DC electromagnetic compatibility filter is used to filter out electromagnetic interference and electric spark interference on the DC side of the bidirectional converter.

9. The vanadium battery energy storage and boosting integrated machine according to claim 8, characterized in that: A load switch and a DC fuse are provided between the corresponding DC power switch and the vanadium battery.

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