Photovoltaic string distributed energy storage battery reverse charging device

Abstract

The utility model discloses a photovoltaic string distributed energy storage battery reverse charging device, which relates to the photovoltaic field and is used for realizing peak load shifting power generation of a photovoltaic power station. The reverse charging device is connected with the distributed energy storage battery through a first terminal, is connected with the photovoltaic inverter through a second terminal, and is connected with a power grid through a third terminal; the reverse charging device is provided with a switch, the first wiring terminal and the second wiring terminal are communicated in the daytime by shifting the switch, network access or power supply of photovoltaic power generation is achieved, and the first wiring terminal and the third wiring terminal are communicated at night, so that the distributed energy storage battery is charged by the mains supply. According to the device, the limitation that a traditional photovoltaic power station can only charge an energy storage battery through photovoltaic panel power generation is solved, external peak-load shifting power generation of the photovoltaic power station is achieved, and the stability of external output power of the photovoltaic power station is improved.

Description

Technical Field

[0001] The utility model relates to the photovoltaic field, in particular to a photovoltaic string distributed energy storage battery reverse charging device. Background Art

[0002] To solve the problem of unstable photovoltaic power generation, a photovoltaic optimizer (MPPT controller, Maximum Power Point Tracking) is connected to each photovoltaic panel. Usually, the output of each photovoltaic optimizer is connected in parallel to a group of energy storage batteries.

[0003] When the photovoltaic power generation is too large to be output externally through the photovoltaic inverter, the excess power will be used to charge the energy storage battery. When the photovoltaic inverter's inverter output power is large and the power generated by the photovoltaic panels cannot meet the demand, the energy storage battery will also output to the photovoltaic inverter to supplement the insufficient power of the photovoltaic panels, thereby ensuring stable power generation of the photovoltaic power station.

[0004] This type of distributed photovoltaic energy storage system can only store the electricity generated by the photovoltaic panels during the day. However, during the day, when the power demand of the grid is high, the photovoltaic panels' power generation is insufficient to charge the energy storage batteries. In some cases, the energy storage batteries may not be able to meet the grid's power requirements. Furthermore, at night, the photovoltaic panels are unable to generate electricity and charge the energy storage batteries. However, the grid load at night is much lower than during the day. This results in significant peaks and valleys in the power generation of the photovoltaic power station. Utility Model Content

[0005] The purpose of the invention of the utility model is to provide a photovoltaic string distributed energy storage battery reverse charging device to solve the above-mentioned problems, so as to realize peak shaving and valley filling power generation in photovoltaic power stations.

[0006] The technical solutions adopted in this utility model are as follows:

[0007] A photovoltaic string distributed energy storage battery reverse charging device, the reverse charging device is used to connect to the distributed energy storage battery via a first terminal, the reverse charging device is also used to connect to a photovoltaic inverter via a second terminal, and the reverse charging device is also used to connect to a power grid via a third terminal; the reverse charging device is provided with a switch, and by turning the switch on the reverse charging device, it is determined whether the first terminal is connected to the second terminal or the third terminal.

[0008] Furthermore, the switch is a single-pole double-throw switch, the two fixed ends of the single-pole double-throw switch are respectively connected to the photovoltaic inverter and the power grid, and the moving end of the single-pole double-throw switch is connected to the distributed energy storage battery.

[0009] Furthermore, the third terminal is connected to a rectifier and filter circuit, and a transformer circuit is connected between the rectifier and filter circuit and the switch.

[0010] Furthermore, the voltage conversion circuit is a DC-DC step-up / step-down circuit.

[0011] Furthermore, the reverse charging device also includes a switch switching circuit connected to the switch, and an activation circuit connected to the switch switching circuit; the switch switching circuit is configured to: under the stimulation of the activation circuit, flip the switch to connect the first terminal with the second terminal, or with the third terminal.

[0012] Furthermore, the excitation circuit is a timer circuit and / or a communication circuit.

[0013] Furthermore, the distributed energy storage battery includes multiple groups of energy storage batteries, and all of the energy storage batteries are connected in series to form the distributed energy storage battery.

[0014] Furthermore, each group of the energy storage batteries is connected to the output end of a photovoltaic optimizer, and each photovoltaic optimizer is connected to a photovoltaic panel.

[0015] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0016] The reverse charging device of this design solves the limitation that traditional photovoltaic power stations can only charge energy storage batteries with photovoltaic panel power generation. It can realize both photovoltaic charging and grid charging. During the peak period of photovoltaic power generation, photovoltaic power generation is used to charge the energy storage battery while meeting the power demand of the grid. During the valley period of power generation, the power demand of the grid is reduced at the same time. At this time, the grid is used to charge the energy storage battery, thereby realizing the peak-shaving and valley-filling power generation of the photovoltaic power station and improving the stability of its external output power. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the wiring diagram of the photovoltaic string distributed energy storage battery reverse charging device.

[0018] Markings in the figure: 1 is the reverse charging device, 2 is the photovoltaic inverter, 3 is the power grid, 4 is the energy storage battery, 5 is the photovoltaic optimizer, 6 is the photovoltaic panel, 11 is the switch, 12 is the rectification and filtering circuit, 13 is the voltage transformation circuit, 14 is the switch switching circuit, and 15 is the excitation circuit. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to the accompanying drawings.

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] The photovoltaic string distributed energy storage battery reverse charging device of this embodiment is used in a photovoltaic power station with a photovoltaic string module, such as Figure 1 As shown, the reverse charging device 1 is connected between the distributed energy storage battery and the photovoltaic inverter 2 .

[0022] The reverse charging device 1 includes three external terminals: a first terminal, a second terminal, and a third terminal. The reverse charging device 1 itself is connected to a distributed energy storage battery via the first terminal, to a photovoltaic inverter 2 via the second terminal, and to the power grid 3 via the third terminal.

[0023] The distributed energy storage battery includes multiple groups of energy storage batteries 4, and all energy storage batteries 4 are connected in series to form the distributed energy storage battery.

[0024] Each group of energy storage batteries 4 is connected to a group of photovoltaic modules and is charged by the excess power of the photovoltaic modules. Figure 1 As shown, the two stages of each group of energy storage batteries 4 are connected in parallel to the two output terminals of a photovoltaic optimizer 5. The two input terminals of each photovoltaic optimizer 5 are connected to the output terminals of a photovoltaic panel 6. The electrical energy converted by the photovoltaic panel 6 undergoes maximum power point tracking (MPPT) processing and output by the photovoltaic optimizer 5. After DC-AC conversion by the photovoltaic inverter 2, it is connected to the grid or load. When there is surplus power, the photovoltaic optimizer 5 charges the connected energy storage batteries 4. At night, the photovoltaic panels 6 output no current, and all photovoltaic optimizers 5 stop working and enter an open circuit state. At this time, the entire photovoltaic power station circuit is connected in series with all energy storage batteries 4, forming a distributed energy storage battery. In this series state, unified series charging can be achieved through a unified charging circuit.

[0025] As described in the background technology section, existing photovoltaic power stations typically output power from energy storage batteries 4 to photovoltaic inverters 2. The reverse charging device 1 of this embodiment retains this basic functionality, while also enabling grid 3 to charge energy storage batteries 4.

[0026] The reverse charging device 1 is equipped with a switch 11. By turning this switch 11, the connection between the first terminal and the second terminal is determined. This determines whether the energy storage battery 4 is connected to the grid 3 to be charged by the grid 3, or connected to the photovoltaic inverter 2 to output power to the photovoltaic inverter 2. During the day, when the switch 11 is turned to connect the first terminal with the second terminal, the electricity converted by the photovoltaic panel 6 is processed by the photovoltaic optimizer 5 and then transmitted to the photovoltaic inverter 2 through the switch 11. After inversion, it supplies power to the grid or load, just like an existing photovoltaic power station. At night, when the switch 11 is turned to connect the first terminal with the third terminal, the photovoltaic panel 6 cannot generate electricity, and the photovoltaic optimizer 6 is disconnected. The entire distributed energy storage battery is connected to the grid 3 via the reverse charging device 1, and the grid 3 charges the distributed energy storage battery. The specific charging process is usually configured with a corresponding circuit on the energy storage battery 4 to control the charging strategy, and charging is performed according to standard processes such as trickle current, constant current, and constant voltage. This is a conventional technical means and does not fall within the scope of this design, so it will not be elaborated on in detail.

[0027] Because the distributed energy storage battery is connected to either the photovoltaic inverter 2 or the grid 3, its switch 11 can be a single-pole double-throw (SPDT) switch. The two fixed terminals of the SPDT switch are connected to the photovoltaic inverter 2 and the grid 3, respectively, while the moving terminal of the SPDT switch is connected to the distributed energy storage battery. Connecting the moving terminal of the SPDT switch to either fixed terminal establishes connectivity between the corresponding terminals.

[0028] Grid 3 transmits AC power, while distributed energy storage batteries store DC power, necessitating AC-DC conversion. In some embodiments, reverse charging device 1 includes a rectifier and filter circuit 12 connected to the third terminal. This circuit 12 rectifies and filters the 220V AC power from grid 3, generating approximately 300V DC power.

[0029] Furthermore, the rated voltage for charging distributed energy storage batteries varies depending on the configuration of the photovoltaic power station. After obtaining the rectified and filtered DC power, the reverse charging device 1 is further equipped with a voltage transformer 13. This transformer 13 is connected between the rectifier and filter circuit 12 and the switch 11 and is used to step up or down the high-voltage DC power of approximately 300V to the total voltage of the distributed energy storage batteries.

[0030] For the rectifier and filter circuit 12 and the transformer circuit 13, existing mature circuits or products can be selected in specific implementation. This embodiment does not limit the specific implementation form. For example, the transformer circuit 13 can directly purchase a DC-DC boost circuit / chip or a DC-DC buck circuit / chip.

[0031] The switch 11 of the reverse charging device 1 can be manually operated or mechanically switched. Mechanical switching is safer and more efficient. The mechanical switching method can be timed or remotely controlled.

[0032] Specifically, the reverse charging device 1 further includes a switch switching circuit 14 connected to the switch 11, and an activation circuit 15 connected to the switch switching circuit 14. The switch switching circuit 14 is configured to, under the stimulation of the activation circuit 15, flip the switch 11 to connect the first terminal to the second terminal, or to connect the first terminal to the third terminal.

[0033] The switch switching circuit 14 is composed of a PLC and necessary peripheral circuits, and is used to perform the toggling action on the switch 11 according to the received command signal (such as a pulse signal, a level signal, etc.).

[0034] For the timed switching method, the excitation circuit 15 can be configured to include a timer circuit, which includes a clock, PLC / MCU / DSP and necessary peripheral circuits. By configuring the switching time in advance, a level signal (such as a high level) is output to the switch switching circuit 14 at this time. When the switch switching circuit 14 receives the high level, it switches the switch 11. When the switch switching circuit 14 receives the next high level, it switches the switch 11 again. Alternatively, the timer circuit outputs a pulse signal at a configured time (such as 06:00) and outputs two consecutive pulse signals at another configured time (such as 18:00). In response to receiving a pulse signal, the switch switching circuit 14 switches the switch 11 to connect the first terminal with the second terminal. In response to receiving two pulse signals, it switches the switch 11 to connect the first terminal with the third terminal.

[0035] For remote command switching, the excitation circuit 15 can be configured to include a communication circuit, which includes an antenna, an IoT communication module, an MCU / DSP / PLC, and peripheral circuits. The communication circuit receives the remote switching command, parses it, generates a corresponding control command, and sends it to the switch switching circuit 14. In response to the received control command, the switch switching circuit 14 toggles the switch 11 to connect the first terminal to the second terminal or the third terminal.

[0036] It should be noted that both the timer circuit and the communication circuit are common circuits in the Internet of Things. For the selection of circuit components and circuit design, those skilled in the art can make corresponding configurations based on actual needs. This embodiment does not limit the specific implementation method.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A photovoltaic string distributed energy storage battery reverse charging device, characterized in that: The reverse charging device is used to connect to the distributed energy storage battery through a first terminal, and is also used to connect to a photovoltaic inverter through a second terminal. The reverse charging device is also used to connect to a power grid through a third terminal. A switch is provided on the reverse charging device, and by turning the switch on the reverse charging device, it is determined whether the first terminal is connected to the second terminal or the third terminal.

2. The photovoltaic string distributed energy storage battery reverse charging device according to claim 1, characterized in that: The switch is a single-pole double-throw switch, the two fixed ends of the single-pole double-throw switch are respectively connected to the photovoltaic inverter and the power grid, and the moving end of the single-pole double-throw switch is connected to the distributed energy storage battery.

3. The photovoltaic string distributed energy storage battery reverse charging device according to claim 1, characterized in that: The third terminal is connected to a rectifier and filter circuit, and a transformer circuit is connected between the rectifier and filter circuit and the switch.

4. The photovoltaic string distributed energy storage battery reverse charging device according to claim 3, characterized in that: The voltage conversion circuit is a DC-DC step-up / step-down circuit.

5. The photovoltaic string distributed energy storage battery reverse charging device according to claim 1, characterized in that: It also includes a switch switching circuit connected to the switch, and an activation circuit connected to the switch switching circuit; the switch switching circuit is configured to: under the stimulation of the activation circuit, flip the switch to connect the first terminal with the second terminal, or with the third terminal.

6. The photovoltaic string distributed energy storage battery reverse charging device according to claim 5, characterized in that: The activation circuit is a timer circuit and / or a communication circuit.

7. The photovoltaic string distributed energy storage battery reverse charging device according to claim 1, characterized in that: The distributed energy storage battery includes multiple groups of energy storage batteries, and all of the energy storage batteries are connected in series to form the distributed energy storage battery.

8. The photovoltaic string distributed energy storage battery reverse charging device according to claim 7, characterized in that: Each group of energy storage batteries is connected to the output end of a photovoltaic optimizer, and each photovoltaic optimizer is connected to a photovoltaic panel.

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