A parallel and off-grid light storage and charging system suitable for a weak power grid

Abstract

The utility model discloses a kind of parallel and off-grid light storage and charging systems suitable for weak electric network, including photovoltaic power generation module, energy storage module, charging module, energy storage converter (PCS), DC bus and smart grid energy management system;The photovoltaic power generation module is connected with DC bus by photovoltaic DC / DC, the energy storage module is connected with DC bus by energy storage converter (PCS), the charging module is connected with DC bus by charging DCDC, the smart grid energy management system is electrically connected with photovoltaic power generation module, energy storage module, charging module, energy storage converter (PCS) respectively;The parallel and off-grid light storage and charging system suitable for weak electric network can improve the tolerance and support capacity of equipment to power grid fluctuation, solve the problem of large voltage fluctuation and poor frequency stability in weak electric network, improve the compatibility and stability of system in weak electric network environment, reduce the disturbance to power grid.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic power technology, and in particular to a grid-connected and off-grid photovoltaic energy storage and charging system suitable for weak power grids. Background Technology

[0002] Weak power grids typically refer to power systems with small grid capacity, large voltage fluctuations, poor frequency stability, and low power supply reliability (such as remote areas, rural power grids, or island power grids).

[0003] Globally, the pursuit of sustainable energy and a low-carbon future is growing stronger. With the leap in photovoltaic technology efficiency, the significant decrease in the cost of energy storage systems, the booming electric vehicle market, and the widespread adoption of mobile electronic devices, photovoltaic-storage-charging systems, as a key bridge connecting solar energy with energy storage and distribution, will increasingly highlight their strategic importance and become a vital force driving the green energy transition.

[0004] Traditional grid-connected photovoltaic-storage-charging systems are susceptible to grid disturbances, have poor stability, and may even shut down due to grid failures, resulting in unsatisfactory performance. Utility Model Content

[0005] The purpose of this invention is to solve the above-mentioned problems by providing a grid-connected and off-grid photovoltaic energy storage and charging system suitable for weak grids, which can improve the equipment's tolerance and support capabilities to grid fluctuations, enhance the system's compatibility and stability in weak grid environments, and reduce disturbances to the grid.

[0006] To achieve the above objectives, the technical solution of this utility model is as follows: a grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids, comprising a photovoltaic power generation module, an energy storage module, a charging module, an energy storage converter, a DC bus, and a smart grid energy management system; the photovoltaic power generation module is connected to the DC bus via a photovoltaic DC / DC converter, the energy storage module is connected to the DC bus via an energy storage converter, the charging module is connected to the DC bus via a charging DC / DC converter, and the smart grid energy management system is electrically connected to the photovoltaic power generation module, the energy storage module, the charging module, and the energy storage converter respectively.

[0007] Preferably, the photovoltaic power generation module includes photovoltaic access 1 and photovoltaic access 2, which are respectively connected to photovoltaic DC / DC1 and photovoltaic DC / DC2.

[0008] Preferably, the charging module includes multiple charging systems, each charging system being connected to a charging DC-DC converter and a PDU, and the charging DC-DC converter being connected to a DC bus.

[0009] Preferably, the energy storage converter tracks the grid voltage frequency and outputs in "current source" mode in sync with the grid.

[0010] Preferably, it also includes a smart grid energy management system for real-time data collection of photovoltaic, charging pile, energy storage and load data.

[0011] Preferably, the smart grid energy management system receives instructions to control the circuit breakers and energy conversion equipment.

[0012] This utility model discloses a grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids, comprising a photovoltaic power generation module, an energy storage module, a charging module, an energy storage converter, a DC bus, and a smart grid energy management system. The photovoltaic power generation module is connected to the DC bus via a photovoltaic DC / DC converter, the energy storage module is connected to the DC bus via the energy storage converter, and the charging module is connected to the DC bus via a charging DC / DC converter. The smart grid energy management system is electrically connected to the photovoltaic power generation module, the energy storage module, the charging module, and the energy storage converter. Compared with the prior art, this grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids has the beneficial effects of improving the equipment's tolerance and support capabilities to grid fluctuations, solving the problems of large voltage fluctuations and poor frequency stability in weak power grids, improving the system's compatibility and stability in weak power grid environments, and reducing disturbances to the power grid. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a grid-connected and off-grid photovoltaic energy storage and charging system suitable for weak power grids according to this utility model.

[0014] Figure 2 This is a schematic diagram illustrating the control principle of an intelligent grid energy management system for a grid-connected and off-grid photovoltaic-storage-charging system suitable for weak grids, according to this utility model.

[0015] Figure 3 This is a schematic diagram of the overall control principle of a grid-connected and off-grid photovoltaic energy storage and charging system suitable for weak power grids according to this utility model. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0017] Please refer to Figure 1-3 A grid-connected and off-grid photovoltaic-storage-charging system suitable for weak grids includes a photovoltaic power generation module, an energy storage module, a charging module, an energy storage converter, a DC bus, and a smart grid energy management system. The photovoltaic power generation module is connected to the DC bus via a photovoltaic DC / DC converter, the energy storage module is connected to the DC bus via an energy storage converter, the charging module is connected to the DC bus via a charging DC / DC converter, and the smart grid energy management system is electrically connected to the photovoltaic power generation module, the energy storage module, the charging module, and the energy storage converter.

[0018] The DC / DC generation module is used to adjust the voltage output from the photovoltaic panel to a voltage range suitable for the inverter input.

[0019] The energy storage module consists of a lithium iron phosphate battery pack and a BMS (battery management system), and is used for energy storage and peak shaving.

[0020] The charging module provides a charging interface for electric vehicles (EVs) and supports DC / DC charging modes.

[0021] The smart grid energy management system is used to coordinate the energy flow of various modules and automatically switch operating modes according to the grid status.

[0022] In this embodiment, the photovoltaic power generation module includes photovoltaic access 1 and photovoltaic access 2, which are respectively connected to photovoltaic DC / DC1 and photovoltaic DC / DC2.

[0023] The charging module includes multiple charging systems, each of which is connected to a charging DC-DC converter and a PDU. The charging DC-DC converter is connected to the DC bus.

[0024] The system adopts a DC-coupled architecture of "photovoltaic-energy storage-charging pile" to reduce AC / DC conversion losses, improve energy conversion efficiency, and reduce grid harmonics. The system is divided into a three-layer control network of "source-storage-load". The bottom layer of energy storage prioritizes response to rapid fluctuations and automatically regulates charging and discharging, breaking away from the limitations of the traditional power grid. It efficiently realizes the transfer and extension of electrical energy in time and space, achieving virtual capacity expansion and reducing capacity expansion and renovation costs. It breaks through the capacity limitations of the traditional power grid on charging facilities. At the same time, the upper-layer photovoltaic system smooths the base load, realizes hierarchical power management, and reduces the burden on the power grid.

[0025] The photovoltaic (PV) power generation modules prioritize powering the charging piles (charging modules). When the PV power exceeds the charging pile power, surplus electricity is used to charge the battery. If the battery is fully charged, surplus electricity is either fed into the grid or the PV controller limits its power. When the PV power is insufficient, power is drawn from the grid to simultaneously power both the charging vehicle and the battery. In the event of a grid failure, automatic switching occurs, with PV and energy storage providing independent power to maintain the charging pile's operation. (The last sentence is a repetition of the previous one and can be omitted.)

[0026] This system enables seamless switching between on-grid and off-grid operation. Specifically, the energy storage converter tracks the grid voltage and frequency, outputting in "current source" mode and synchronizing with the grid. By rapidly detecting grid conditions (such as power outages or voltage anomalies), it switches to "voltage source" mode to establish stable voltage and frequency, supplying power to local loads. Simultaneously, at the moment of switching, the energy storage battery quickly compensates for the power gap, preventing a sudden voltage drop at the load end, with the switching time controlled in milliseconds (<20ms).

[0027] Furthermore, it also includes a smart grid energy management system, which is used to collect data on photovoltaics, charging piles, energy storage, and loads in real time. The smart grid energy management system receives instructions to control circuit breakers and energy conversion equipment.

[0028] In short, the smart grid energy management system collects, processes, and transmits real-time analog, digital, non-electrical, and operational information related to photovoltaics, charging piles, energy storage, and loads. It also alarms, displays, and records over-limit and position change information. Furthermore, it controls the start / stop, operation / maintenance status switching, grid connection / off-grid switching, and charging / discharging of circuit breakers and energy conversion equipment within the system. Based on the system's set energy management strategy or receiving instructions from the higher-level system, it issues adjustment commands for real-time power flow control.

[0029] The entire system integrates multiple protection measures such as electrical protection, operation monitoring, and multiple detection. It is suitable for scenarios with fast charging needs for electric vehicles, such as charging stations, highway service areas, shopping mall parking lots, and residential areas. Through multiple protection mechanisms, the system's safety and reliability are improved. Its wide adaptability to various scenarios expands the application scope of the photovoltaic-storage-charging system and promotes the popularization of green energy in different scenarios.

[0030] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids, characterized in that, It includes a photovoltaic power generation module, an energy storage module, a charging module, an energy storage converter, a DC bus, and a smart grid energy management system; the photovoltaic power generation module is connected to the DC bus via a photovoltaic DC / DC converter, the energy storage module is connected to the DC bus via an energy storage converter, the charging module is connected to the DC bus via a charging DC / DC converter, and the smart grid energy management system is electrically connected to the photovoltaic power generation module, the energy storage module, the charging module, and the energy storage converter respectively.

2. The grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids according to claim 1, characterized in that, The photovoltaic power generation module includes photovoltaic access 1 and photovoltaic access 2, which are respectively connected to photovoltaic DC / DC1 and photovoltaic DC / DC2.

3. The grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids according to claim 1, characterized in that, The charging module includes multiple charging systems, each of which is connected to a charging DC-DC converter and a PDU. The charging DC-DC converter is connected to the DC bus.

4. The grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids according to any one of claims 1-3, characterized in that, The energy storage converter tracks the grid voltage frequency and outputs in "current source" mode in sync with the grid.

5. The grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids according to claim 1, characterized in that, It also includes a smart grid energy management system, which is used to collect data on photovoltaics, charging piles, energy storage, and loads in real time.

6. The grid-connected and off-grid photovoltaic-storage-charging system suitable for weak power grids according to claim 5, characterized in that, The smart grid energy management system receives instructions to control circuit breakers and energy conversion equipment.

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