Energy scheduling method of collaborative light storage and charging alternating current and direct current hybrid micro-grid system
By constructing a microgrid topology with a hybrid AC/DC bus and employing a refined scheduling strategy, the problems of high energy loss and resource fragmentation in existing photovoltaic-storage-charging systems have been solved. This has enabled efficient and flexible energy coordination, complies with national microgrid standards, and improves system stability and economy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG ELECTRIC HIMILE ENERGY SAVING TECH CO LTD
- Filing Date
- 2025-12-10
- Publication Date
- 2026-04-24
AI Technical Summary
Existing photovoltaic-storage-charging systems suffer from significant energy losses due to multiple AC/DC conversions, fragmented resource control, and difficulty in achieving aggregation and coordination. Their system architecture does not conform to national microgrid standards, and V2G charging piles are not effectively integrated into local energy dispatch, resulting in low energy efficiency, poor stability, and difficulty in meeting the requirements of standardized microgrids.
A microgrid topology with a hybrid AC/DC bus is constructed. Photovoltaics, energy storage, and charging piles are connected to the grid through integrated microgrid devices to achieve efficient interconnection of multiple sources. The scheduling logic of "photovoltaics first, energy storage support, grid power as a backup, and V2G interaction" is adopted. Combined with electricity price time and energy storage status, a refined operation strategy is formed, and a monitoring and protection system is configured to incorporate V2G charging piles to participate in local energy dispatch.
It improves the overall system efficiency to over 92%, significantly reduces energy loss, achieves real-time power coordination between photovoltaics, energy storage, charging and the grid, enhances system flexibility and economy, complies with national microgrid standards, has the ability to support critical loads, and reduces electricity purchase costs by 30%.
Smart Images
Figure CN121923296A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of microgrid control technology, specifically relating to an energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system. Background Technology
[0002] With the rapid popularization of distributed photovoltaic power generation and electric vehicle charging facilities in small commercial settings such as parks and parking lots, a large number of intermittent power sources and impulsive loads are connected to the distribution network, resulting in frequent reversals of power flow direction, increased node voltage fluctuations, and a significant widening of peak-valley load differences, posing a severe challenge to the safe and stable operation of traditional distribution networks.
[0003] Existing integrated photovoltaic, energy storage, and charging systems mostly adopt a fully AC-coupled architecture. The photovoltaic power generation unit is connected to a 0.4kV AC bus via an inverter, and the electric vehicle charging pile draws power from the same AC bus, which is then rectified internally to convert the power into DC for the vehicle's battery. Under this architecture, the DC power generated by the photovoltaic system needs to be inverted into AC power first, and then rectified into DC power by the charging pile, undergoing two power electronic conversion processes, resulting in significant energy loss. The overall system efficiency is typically below 85%.
[0004] In such systems, the control strategies for photovoltaic power generation units, energy storage devices, and charging facilities are independent, lacking a unified energy coordination mechanism, making it difficult to achieve dynamic power balance among "source, grid, load, and storage" within the local area. When photovoltaic output fluctuates or charging load suddenly increases, the system cannot respond quickly, easily leading to voltage exceeding limits or equipment overload. Most existing projects only physically integrate photovoltaics, energy storage, and charging piles, without configuring core functional modules of a microgrid that meet national standards.
[0005] According to GB / T 33589-2017, "Technical Specifications for Microgrid Access to Power Systems," microgrids should possess basic internal power self-balancing capabilities and be equipped with complete monitoring, protection, and energy management subsystems. Currently, most photovoltaic-storage-charging projects lack these functions and cannot be recognized as standardized microgrid units, thus facing limitations in grid connection approval and dispatch interaction. Although academia has proposed new architectures such as DC microgrids to improve efficiency, in small-scale commercial applications, they still face problems such as high costs, complex topologies, and a lack of standardized interfaces. A compact, economically feasible, and practical solution supporting efficient multi-energy synergy has yet to be developed. Summary of the Invention
[0006] This invention aims to solve the technical problems in existing photovoltaic-storage-charging systems, such as high energy loss due to multiple AC / DC conversions, fragmented distributed resource control making aggregation and coordination difficult, system architecture incompatibility with national microgrid standards, and the ineffective integration of V2G charging pile capabilities into the local energy dispatch system. The technical solution adopted in this invention is as follows: A method for energy dispatching a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system, comprising an integrated microgrid device connecting a DC bus and an AC bus, wherein the AC bus is connected to the power grid via a box-type transformer, characterized by the following steps: A portion of the installed capacity of the distributed photovoltaic unit is connected to the AC bus via a DC / AC inverter, while the other portion of the installed capacity of the distributed photovoltaic unit is connected to the DC bus via a microgrid integrated device. Connect the DC-DC charging pile of the microgrid integrated device to the DC bus, and connect the energy storage battery pack to the DC bus through the microgrid integrated device; connect the AC charging pile to the AC bus through the AC charging pile distribution box, and connect the V2G charging pile and DC charging pile to the AC bus. Connect the data management center of the microgrid energy management system to the converged terminal, and connect the converged terminal to the photovoltaic-storage-charging AC / DC hybrid microgrid system. The converged terminal collects data from V2G charging piles, DC charging piles, AC charging piles, DC / AC inverters, DC-DC DC charging piles, and integrated microgrid devices. The microgrid energy management system collects real-time data on photovoltaic output (Ppv), charging load (Pload), energy storage state of charge (SOC), and grid electricity price signals. During off-peak hours, the photovoltaic output is used to charge the energy storage device to 100% SOC, and any excess photovoltaic power is used for charging piles. If the photovoltaic output is insufficient to meet the charging pile demand, the grid power supply is used to supplement the power, and the use of the energy storage device to discharge and power the charging pile is prohibited. During peak hours, the energy storage device discharges at full power to ensure the power supply to the charging pile. If the photovoltaic output is still available, it will work in conjunction with the energy storage device to supply power. When the total power supply exceeds the load demand, the surplus power is fed back into the grid to achieve peak-valley arbitrage. During normal periods, if the energy storage SOC is lower than a set threshold, the energy storage device's power supplementation strategy is activated.
[0007] Preferably, the method for activating the energy storage device power replenishment strategy is as follows: prioritize the use of photovoltaic power, and when photovoltaic power is insufficient, use grid power through the transformer to replenish the power to the threshold; at the same time, the power supply for the charging pile is only provided by photovoltaic power or grid power, and it is prohibited to use the energy storage device to discharge and power the charging pile.
[0008] Preferably, when the electricity price is high, or when a dispatch instruction is received, or when the electric vehicle battery SOC is greater than 30% and the user authorizes it, the discharge function of the V2G charging pile is activated, so that the vehicle's electrical energy is fed back to the DC bus to participate in local power balancing or fed back to the grid.
[0009] Preferably, the AC busbar is also connected to the lighting distribution box.
[0010] Preferably, the energy storage device uses a lithium iron phosphate battery pack.
[0011] Preferably, the photovoltaic-storage-charging AC / DC hybrid microgrid system is equipped with a protection and monitoring subsystem, which includes a grid connection point circuit breaker, an anti-islanding protection relay, a power quality analyzer, and video monitoring equipment.
[0012] The beneficial technical effects of this invention are as follows: This invention constructs a compact microgrid topology based on an AC / DC hybrid bus, achieving efficient interconnection and plug-and-play functionality across multiple power source ports, including photovoltaic (PV), energy storage, charging, and grid. It proposes a four-level collaborative scheduling logic: "PV priority, energy storage support, grid backup, and V2G interaction," and combines this with electricity price periods, PV output status, and energy storage state of charge (SOC) thresholds to form a refined operation strategy of "valley charging, peak dissipation, and normal-day backup." The invention embeds national standards for microgrid functional requirements into the system architecture, creating a replicable and scalable standardized solution. For the first time, it achieves energy coupling between V2G charging piles and the local DC bus in a small-scale commercial scenario, enabling electric vehicles to deeply participate in the microgrid's local balancing, rather than simply acting as a reverse power source for the main grid. This invention improves processing efficiency and power supply reliability, increasing the overall system efficiency to over 92% and significantly reducing energy losses caused by multiple AC / DC conversions. By constructing an AC / DC hybrid bus, it achieves single-stage power supply from PV to DC loads, reducing unnecessary energy conversion steps. The system achieves real-time power coordination and dynamic balance between photovoltaic power generation, electrochemical energy storage, electric vehicle charging, and the public power grid, effectively suppressing power flow fluctuations in the distribution network. While reducing electricity purchase costs by approximately 30%, it ensures the system has at least two hours of critical load support capability during grid failures. The system fully integrates three core subsystems: monitoring, protection, and energy management, conforms to national microgrid standards, and possesses standardized characteristics of dispatchability, communication capability, and controllability. Furthermore, by incorporating the discharge capacity of V2G charging piles into the local energy dispatch system, electric vehicles become readily available mobile energy storage resources, enhancing the system's operational flexibility and economy. Attached Figure Description
[0013] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is an architectural diagram of a photovoltaic-storage-charging AC / DC hybrid microgrid system according to an embodiment of the present invention; Figure 2 This is an architecture diagram of the microgrid energy management system according to an embodiment of the present invention; Figure 3 This is an illustration of energy dispatching in a microgrid energy management system according to an embodiment of the present invention. Detailed Implementation
[0014] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0015] like Figure 1 As shown, a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system includes an integrated microgrid device. This integrated device is an existing product, such as the HTMG L-0.4 / 100kW series integrated microgrid device (flexible DC cabinet). This product includes five external interfaces. For ease of description, the 100kW bidirectional PCS (AC / DC) converter is named S010, the 60kW #1 photovoltaic DC / DC converter is named S002, the 60kW #2 photovoltaic DC / DC converter is named S003, the 50kW energy storage DC / DC converter is named S005, and the 60kW DC-DC charging pile is named S006 (DC input, DC output). It is equipped with a local monitoring system, enabling local energy consumption within the microgrid. During the day, photovoltaic power generation powers the DC charging pile within the microgrid, and excess energy is stored in the energy storage device. At night, the DC charging pile is powered by the grid and the energy storage device, with unified allocation through the local monitoring system to minimize energy exchange between the grid and the microgrid.
[0016] Taking a certain project as an example, the total installed capacity of the distributed photovoltaic units in this project is 238.08 kWp, of which 119.04 kWp (i.e., photovoltaic array S015) is connected to inverter DC / AC S016. Inverter DC / AC S016 converts DC power to AC power and connects it to the 400V AC bus S011 for grid connection. The remaining 119.04 kWp (i.e., photovoltaic array S001) is connected to photovoltaic DC / DC converter S002 and photovoltaic DC / DC converter S003 respectively. Because the photovoltaic capacity is too large, it is connected to the microgrid integrated device through the input terminals of photovoltaic DC / DC converter S002 and photovoltaic DC / DC converter S003. Then, the output terminals of photovoltaic DC / DC converter S002 and photovoltaic DC / DC converter S003 are connected to the 750V DC bus S012 respectively. The energy storage battery pack S004 is connected to the same 750V DC bus S012 via the energy storage DC / DC converter S005 of the microgrid integrated device, enabling bidirectional charging and discharging control of the energy storage battery pack S004. The 60kW DC-DC charging pile S006 is directly connected to the 750V DC bus S012 and can directly receive DC power from the photovoltaic array or the energy storage battery pack without the need for additional rectification.
[0017] The bidirectional PCS converter S010 of the microgrid integrated device connects one end to the 750V DC bus S012 and the other end to the 400V AC bus S011, enabling flexible power exchange between the DC bus S012 and the AC bus S011. The 750V DC bus S012 and the 400V AC bus S011 are flexibly coupled through the bidirectional PCS converter S010, forming an AC / DC hybrid bus architecture.
[0018] The S004 energy storage battery pack uses lithium iron phosphate batteries with a rated power of 50kW and a capacity of 129kWh.
[0019] The 400V AC bus S011 also connects to the AC input terminals of the 120kW V2G charging pile S007, the two-to-one 120kW DC charging pile S008, the AC charging pile distribution box S018, the lighting distribution box S017, and the 630kVA transformer S014. The transformer S014 is further connected to the public power grid. The AC charging pile distribution box S018 connects to three 7kW AC charging piles S009. The core of the V2G charging pile lies in the "bidirectional charging and discharging" technology, which gives the V2G charging pile dual functions of "charging + discharging".
[0020] In this hybrid microgrid system of photovoltaic, energy storage, and charging, the electric vehicle charging unit includes a V2G charging pile S007, a DC charging pile S008, a DC charging pile S006, and three AC charging piles S009.
[0021] In this embodiment, the integrated microgrid device serves as the core integration unit, encapsulating AC / DC converters and multiple DC / DC converters within the same cabinet and providing standardized AC / DC interfaces for easy engineering deployment. All devices involving DC energy interaction (photovoltaics, energy storage, and a 60kW DC / DC charging pile) are efficiently interconnected via a 750V DC bus S012, minimizing the number of AC / DC conversions and improving overall system efficiency. This structure not only meets the local demand for high-proportion renewable energy consumption but also maintains controllable energy exchange with the grid through the bidirectional PCS converter S010, conforming to the basic technical characteristic of microgrids: seamless grid-connected / off-grid switching.
[0022] The photovoltaic-storage-charging AC / DC hybrid microgrid system can also be configured with a protection and monitoring subsystem. The protection and monitoring subsystem includes a grid connection point circuit breaker, an anti-islanding protection relay, a power quality analyzer, and video monitoring equipment. The grid connection point circuit breaker, anti-islanding protection relay, power quality analyzer, and video monitoring equipment are all installed nearby to ensure the safe and compliant operation of the photovoltaic-storage-charging AC / DC hybrid microgrid system.
[0023] The photovoltaic-storage-charging AC / DC hybrid microgrid system is a standardized microgrid unit connected to the distribution network through a single point of common coupling (PCC) in a transformer substation (S014). It is equipped with a grid connection point circuit breaker, anti-islanding protection device, online power quality monitoring equipment, and video surveillance system, meeting the requirements of relevant standards such as GB / T 34930 and GB / T 14285, and conforming to the basic definition of microgrids in GB / T33589-2017.
[0024] like Figure 2 As shown, the microgrid energy management system includes a data management center S019 and a converged terminal S020. The data management center S019 connects to the converged terminal S020 at the site via a communication bus for data exchange. The converged terminal S020 connects to the photovoltaic-storage-charging AC / DC hybrid microgrid system via a communication bus for data exchange. The data management center S019 collects the operating parameters of the photovoltaic-storage-charging AC / DC hybrid microgrid system in real time and issues control commands. The data management center S019 uses the State Grid's control platform, which can access user data and perform remote monitoring. The converged terminal S020 is the SCU device used in the field, collectively referred to as the converged terminal, used for data aggregation and transmission; specifically, it can use equipment from Beijing Zhixin. The integrated terminal S020 collects data from V2G charging piles S007, DC charging piles S008, AC charging piles S009, DC / AC inverters S016, DC-DC charging piles S006, and microgrid integrated devices. The integrated terminal S020 can control the microgrid integrated devices. The data collected by the microgrid integrated devices includes the status of photovoltaic DC / DC converter S002 (1#), photovoltaic DC / DC converter S003 (2#), and energy storage DC / DC converter S005.
[0025] The microgrid energy management system collects real-time data on photovoltaic output (Ppv), charging load (Pload), energy storage state of charge (SOC), and grid electricity price signals, and executes refined energy dispatch methods. (See also: [link to relevant documentation]). Figure 3 , Figure 3In this context, I, II, and III refer to priority levels, with I > II > III. This method divides the day into three periods based on the State Grid's typical peak-valley electricity price: peak period, normal period, and valley period. During the valley period, the system prioritizes utilizing sufficient photovoltaic output to charge the energy storage to 100% SOC. Once fully charged, excess photovoltaic power is used to power charging piles. If photovoltaic power is insufficient to meet the charging pile demand, grid power supplements the supply, and the use of energy storage for charging piles is strictly prohibited to ensure that energy storage prioritizes charging. During the peak period, the energy storage discharges at full power to prioritize power supply to charging piles. If photovoltaic power still has output, it works in conjunction with energy storage to provide power. When total power supply exceeds load demand, surplus electricity is fed back into the grid via an AC / DC converter, achieving peak-valley arbitrage. During normal periods, the system continuously monitors the State of Charge (SOC) of the energy storage. If it falls below a set threshold (configurable), a power replenishment strategy is activated: priority is given to using photovoltaic power, and if photovoltaic power is insufficient, low-power mains power is used via transformer S014 to replenish the voltage to the threshold. Simultaneously, the charging pile's power supply is solely provided by photovoltaic or mains power, prohibiting the use of energy storage devices to maintain emergency backup capacity for grid interruptions and other unforeseen circumstances. When the V2G charging pile discharge activation conditions are met (e.g., during periods of high electricity prices, receiving dispatch instructions, electric vehicle battery SOC greater than 30%, and user authorization), the V2G charging pile's discharge function is activated, allowing vehicle power to be fed back to the DC bus for local power balancing or grid feedback.
[0026] In the embodiments of the present invention, all technical features not described in detail are existing technologies or conventional technical means, and will not be repeated here.
[0027] Finally, it should be noted that the above embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit them. The scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention.
Claims
1. An energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system, wherein the photovoltaic-storage-charging AC / DC hybrid microgrid system includes an integrated microgrid device connecting a DC bus and an AC bus, the AC bus being connected to the power grid via a box-type transformer, characterized in that, Includes the following steps: A portion of the installed capacity of the distributed photovoltaic unit is connected to the AC bus via a DC / AC inverter, while the other portion of the installed capacity of the distributed photovoltaic unit is connected to the DC bus via a microgrid integrated device. Connect the DC-DC charging pile of the microgrid integrated device to the DC bus, and connect the energy storage battery pack to the DC bus through the microgrid integrated device; connect the AC charging pile to the AC bus through the AC charging pile distribution box, and connect the V2G charging pile and DC charging pile to the AC bus. Connect the data management center of the microgrid energy management system to the converged terminal, and connect the converged terminal to the photovoltaic-storage-charging AC / DC hybrid microgrid system. The converged terminal collects data from V2G charging piles, DC charging piles, AC charging piles, DC / AC inverters, DC-DC DC charging piles, and integrated microgrid devices. The microgrid energy management system collects real-time data on photovoltaic output (Ppv), charging load (Pload), energy storage state of charge (SOC), and grid electricity price signals. During off-peak hours, the photovoltaic output is used to charge the energy storage device to 100% SOC, and any excess photovoltaic power is used for charging piles. If the photovoltaic output is insufficient to meet the charging pile demand, the grid power supply is used to supplement the power, and the use of the energy storage device to discharge and power the charging pile is prohibited. During peak hours, the energy storage device discharges at full power to ensure the power supply to the charging pile. If the photovoltaic output is still available, it will work in conjunction with the energy storage device to supply power. When the total power supply exceeds the load demand, the surplus power is fed back into the grid to achieve peak-valley arbitrage. During normal periods, if the energy storage SOC is lower than a set threshold, the energy storage device's power supplementation strategy is activated.
2. The energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system according to claim 1, characterized in that, The method for activating the energy storage device power replenishment strategy is as follows: prioritize the use of photovoltaic power, and when photovoltaic power is insufficient, use the mains power through the box-type transformer to replenish the power to the threshold; at the same time, the power supply for the charging pile is only provided by photovoltaic power or mains power, and it is prohibited to use the energy storage device to discharge and power the charging pile.
3. The energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system according to claim 2, characterized in that, When the electricity price is high, or when a dispatch instruction is received, or when the electric vehicle battery SOC is greater than 30% and the user authorizes it, the discharge function of the V2G charging pile is activated, so that the vehicle's electrical energy is fed back to the DC bus to participate in local power balancing or fed back to the grid.
4. The energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system according to claim 1, characterized in that, The AC busbar also connects to the lighting distribution box.
5. The energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system according to claim 1, characterized in that, The energy storage device uses lithium iron phosphate battery packs.
6. The energy dispatching method for a collaborative photovoltaic-storage-charging AC / DC hybrid microgrid system according to claim 1, characterized in that, The photovoltaic-storage-charging AC / DC hybrid microgrid system is equipped with a protection and monitoring subsystem, which includes a grid connection point circuit breaker, an anti-islanding protection relay, a power quality analyzer, and video monitoring equipment.