Photovoltaic energy storage system

Abstract

The utility model relates to the technical field of photovoltaic energy storage, and discloses a photovoltaic energy storage system, so as to improve the utilization rate of branches and realize capacity expansion. The photovoltaic energy storage system comprises at least two branches connected with a photovoltaic inverter, the source end of each branch is a photovoltaic end provided with a solar panel, and each branch is provided with a battery cluster and a photovoltaic controller which are connected in parallel. Each battery cluster and each photovoltaic controller are respectively in communication connection with an upper control system, and at least one branch is connected in series with a DC-to-DC power supply capable of dynamically adjusting a voltage value according to an instruction of the upper control system. Therefore, the upper control system can determine the regulation voltage value of the DC-to-DC power supply in real time according to the dynamic state information of the battery cluster and the photovoltaic controller on the target branch, so that the power utilization of the target branch is maximized.

Description

TECHNICAL FIELD

[0001] The utility model relates to photovoltaic energy storage technical field especially relates to a photovoltaic energy storage system. BACKGROUND

[0002] The demand of energy market in China is growing, especially in the field of new energy, the application demand of photovoltaic and energy storage technology also increases.

[0003] With the increase of photovoltaic and energy storage installed capacity, in photovoltaic application scene and photovoltaic + energy storage application scene, each station often has multiple branches, and each branch has a battery cluster and a photovoltaic controller in parallel relationship, and each battery cluster and each photovoltaic controller are connected with the upper control system to realize the regulation and control operation, which often has the problems of unstable voltage and low power generation efficiency, and the photovoltaic of single branch cannot be expanded. UTILITY MODEL CONTENT

[0004] The utility model discloses a photovoltaic energy storage system to improve the utilization rate of branch and realize expansion.

[0005] In order to achieve the above purpose, the utility model discloses a photovoltaic energy storage system, at least two branches are connected with photovoltaic inverter, the source end of each branch is a photovoltaic end with solar panel, one battery cluster and one photovoltaic controller in parallel relationship are arranged on each branch, and each battery cluster and each photovoltaic controller are connected with the upper control system, wherein, at least one branch is connected with a direct current to direct current power supply capable of dynamically adjusting voltage value according to the instruction of the upper control system, so that the upper control system can determine the adjustment voltage value of direct current to direct current power supply according to the dynamic state information of battery cluster and photovoltaic controller on the target branch to maximize the power utilization of the target branch.

[0006] Preferably, the direct current to direct current power supply and the external input power source are connected with a bidirectional inverter.

[0007] Preferably, the bidirectional inverter is connected with at least two direct current to direct current power supplies distributed on different branches.

[0008] As a comparison, in the traditional branch, the battery cluster and the photovoltaic controller are in parallel, which can lower the output voltage of photovoltaic, reduce the system output power under the same current, and cannot track the highest power.

[0009] The utility model discloses after adopting the branch series connection direct current to direct current power supply, the voltage that is transported to photovoltaic inverter is the parallel voltage of battery cluster and photovoltaic controller and the voltage output of direct current to direct current power supply, and the bus voltage is made consistent with the battery cluster voltage through the voltage of direct current to direct current power supply, thereby make the photovoltaic controller and bus isolation will not directly reduce the voltage that photovoltaic source end exports, and there is no power loss caused by pressure difference.

[0010] The utility model will be further explained in detail below with reference to the drawings. DRAWINGS

[0011] The drawings constituting a part of the present application are used to provide further understanding of the utility model, and the illustrative embodiment of the utility model and its explanation are used to explain the utility model, and do not constitute undue limitation to the utility model. In the drawings:

[0012] Figure 1 It is the architecture schematic view of photovoltaic energy storage system disclosed by the utility model embodiment. DETAILED DESCRIPTION

[0013] The embodiment of the utility model will be explained in detail below with reference to the drawings, but the utility model can be implemented in multiple different ways limited and covered by the claims.

[0014] Embodiment 1

[0015] The embodiment discloses a kind of photovoltaic energy storage systems, as shown in Fig. Figure 1 It includes subsequent functional modules: battery cluster;Upper control system;AC / DC, bidirectional inverter;DCDC, direct current to direct current power supply;Upper control system;PV, photovoltaic;PV Inverter, photovoltaic inverter;MPPT, photovoltaic controller. The division of labor of each functional module is as follows:

[0016] Bidirectional inverter (AC / DC), for responsible for converting alternating current energy into direct current energy, can also convert direct current energy into alternating current energy.

[0017] Photovoltaic (PV), for responsible for converting light energy into direct current energy.

[0018] Photovoltaic controller (MPPT), battery cluster and upper control system, for linkage to adjust photovoltaic voltage and current in real time, so that photovoltaic system with maximum power output.

[0019] A DC-DC converter (DCDC) transforms electrical energy from one voltage value to another controllable voltage value in a DC circuit.

[0020] A photovoltaic inverter is an inverter that converts the variable DC voltage generated by photovoltaic (PV) solar panels into AC power at the mains frequency. This AC power can be fed back into commercial transmission systems or supplied to off-grid power grids.

[0021] In this embodiment, the positive and negative terminals of the DC voltage output from a single-phase or three-phase input AC / DC module can be directly connected to the DC bus of the DC-DC converter, providing support for multiple DC-DC input voltages. The negative terminal of the DC-DC converter is connected to the positive terminal of the MPPT module, and the positive terminal of the DC-DC converter is connected to the positive input of the PV Inverter. The control technology of the AC / DC and DC-DC units is known technology, and the corresponding control is also existing technology, so it will not be described in detail.

[0022] exist Figure 1 In this configuration, after a single PV DC circuit is connected to the MPPT module, each circuit has a battery pack connected in parallel to the DC bus. A DC-DC converter is connected in series in the positive circuit of each circuit's DC bus, and then connected to the PV Inverter. In other words, each circuit has a DC-to-DC power supply connected in series, which can dynamically adjust its voltage value according to the instructions of the upper control system. This allows the upper control system to determine the adjustment voltage value of the DC-to-DC power supply in real time based on the dynamic status information of the battery pack and the PV controller on the target circuit, thereby maximizing the power utilization of that target circuit.

[0023] For example, during the day when there is sunlight, the output of the PV will change due to differences in light intensity, shading, angle, and other factors. Therefore, the output voltage of the DC-DC converter in each branch will also change. When the PV output power is high, the upper control system will increase the voltage of the main circuit DC bus to charge the battery cluster at a higher power. When the PV output power is low, the upper control system will decrease the voltage of the main circuit DC bus to charge the battery cluster at a lower power or not charge it at all. When the battery cluster is fully charged, the output voltage of the PV plus the DC-DC converter will be consistent with the battery cluster voltage, and the battery cluster will not be charged.

[0024] based on Figure 1 The system architecture shown below corresponds to the following control steps:

[0025] Step 1: Power on the AC / DC module and supply DC power to the input terminals of multiple DC-DC converters.

[0026] Step 2: Control the battery cluster to energize the DC bus of each branch, at which point the high voltage side of the MPPT is energized.

[0027] Step 3: The upper control system reads the voltage of each branch battery cluster.

[0028] Step 4: The upper control system simultaneously sends out the start-up command for each branch DC-DC converter, and each branch DC-DC converter controls its own output voltage according to the control data sent by the upper control system.

[0029] Step 5: The upper control system simultaneously sends the start-up MPPT of each branch. The upper control system reads the voltage and charge status of the battery clusters of each branch, performs internal calculations, and sends the target output voltage and output power of each branch MPPT to its respective MPPT.

[0030] Step 6: The upper-level control system sends the calculated control quantity data for each branch to the corresponding DC-DC converter. The output power of the DC-DC converter can be either forward or reverse power, thereby controlling the AC / DC input power to approximately zero and reducing the use of other electrical energy.

[0031] When PV inverter power generation is limited, or when PV power generation exceeds the inverter's output, the output voltage of the DC-DC converter is adjusted to charge the battery clusters, resolving the issue of unused excess power and thus eliminating PV power wastage. When the battery clusters are fully charged, the DC-DC converter's output voltage is adjusted to match the battery cluster voltage, ensuring this voltage is higher than or equal to the main circuit's DC bus voltage; in this case, the battery clusters do not charge. Conversely, when PV power generation is insufficient, the DC-DC converter's output voltage is adjusted to discharge the battery clusters, supplementing the output power.

[0032] In summary, the photovoltaic energy storage system disclosed in this embodiment has at least the following advantages compared to traditional branch circuits:

[0033] This invention employs a branch-series DC-to-DC power supply. The voltage supplied to the photovoltaic inverter is the sum of the parallel voltage of the battery cluster and the photovoltaic controller, and the output voltage of the DC-to-DC power supply. By adjusting the voltage of the DC-to-DC power supply to match the bus voltage with the battery cluster voltage, isolating the photovoltaic controller from the bus does not directly reduce the output voltage of the photovoltaic source, thus eliminating power loss due to voltage difference. Furthermore, based on the architecture disclosed in this invention, the power output of the bus can be controlled by controlling the voltage of the DC-to-DC power supply. For example, raising the voltage of the DC-to-DC power supply to be higher than the bus voltage will increase the photovoltaic output at the source, and vice versa, thereby controlling and maximizing the photovoltaic output at the source.

[0034] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A photovoltaic energy storage system, comprising at least two branches connected to a photovoltaic inverter, each branch having a photovoltaic end equipped with solar panels at its source, and each branch having a battery cluster and a photovoltaic controller connected in parallel, wherein each battery cluster and each photovoltaic controller establish a communication connection with a higher-level control system, characterized in that, At least one branch is connected in series with a DC-to-DC power supply whose voltage value can be dynamically adjusted according to the instructions of the upper control system, so that the upper control system can determine the adjustment voltage value of the DC-to-DC power supply in real time according to the dynamic status information of the battery cluster and photovoltaic controller on the target branch, so as to maximize the power utilization of the target branch.

2. The photovoltaic energy storage system according to claim 1, characterized in that, A bidirectional inverter is connected between the DC-to-DC power supply and the external input power supply.

3. The photovoltaic energy storage system according to claim 2, characterized in that, The bidirectional inverter is connected to at least two DC-to-DC power supplies distributed on different branches.

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