Low voltage photovoltaic power router and control method thereof

Abstract

This invention discloses a low-voltage photovoltaic power router and its control method, belonging to the field of power technology. It includes: a local control center: acquiring the power router's energy storage status information, total power of the electrical load, photovoltaic unit power generation, and cloud-based control commands or grid-connected electricity price information; determining the energy dispatch mode based on the comparison between the cloud-based control commands or grid-connected electricity price information and a preset price threshold; and determining the energy flow direction based on the comparison between the photovoltaic unit power generation, the energy storage unit's power supply capacity, and the total power of the electrical load under the energy dispatch mode; an energy storage unit: used to supply electrical energy and store excess electrical energy; and three sets of external control ports, respectively connected to the photovoltaic unit, the low-voltage distribution network, and the electrical load. Based on the characteristics of dischargeable electrical loads and a bidirectional converter, this invention enables power dispatch between local loads and grid connection of surplus electricity, reducing reliance on new energy generation ports.

Description

Technical Field

[0001] This invention relates to the field of power technology, specifically to a low-voltage photovoltaic power router and its control method. Background Technology

[0002] With the continuous increase in installed capacity of new energy photovoltaics, the full grid connection of high-proportion renewable energy has increased the complexity of power system regulation. The power system faces challenges in terms of operational stability and efficient absorption of renewable energy.

[0003] For example, Chinese publication CN120879725A proposes a flexible microgrid system and configures a power router to achieve cross-regional power routing and real-time sharing through cross-regional flexible DC interconnection and energy routing system.

[0004] The routers mentioned above only serve electrical isolation and AC rectification functions. They separate energy storage, photovoltaics, and routers for communication, resulting in large size and inconvenient installation and management. For example, Chinese publication CN120601525A proposes a high-voltage AC input power router that connects to various distributed power sources through multiple ports to supply power to the load and is responsible for the scheduling and management of multi-source energy. The aforementioned router has a low DC output voltage, and excess power cannot be fed back to the power distribution network.

[0005] Based on this, the present invention designs a low-voltage photovoltaic power router and its control method to solve the above problems. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a low-voltage photovoltaic power router and its control method.

[0007] To achieve the above objectives, the present invention provides the following technical solution: Low-voltage photovoltaic power router, including: Local control center: Obtains energy storage status information, total power of electrical load, power generation of photovoltaic unit, and cloud control instructions or electricity grid connection price information from the power router. Based on the comparison between the cloud control instructions or electricity grid connection price information and the preset electricity price threshold, it determines the energy dispatch mode. Under the energy dispatch mode, it further determines the energy flow direction based on the comparison relationship between the power generation of photovoltaic unit, the power supply capacity of energy storage unit, and the total power of electrical load. Energy storage unit: used to supply electrical energy and store excess electrical energy; The three sets of external control ports are connected to the photovoltaic unit, the low-voltage distribution network, and the electrical load, respectively. The DC bus is electrically connected to the energy storage unit and the three sets of external control ports. The local control center is interconnected with the functional units on the DC bus side via communication.

[0008] Furthermore, electrical loads include dischargeable electrical loads and non-dischargeable electrical loads; The control ports connected to the electrical loads are bidirectional DC ports and unidirectional output DC ports. The bidirectional DC ports are connected to the dischargeable electrical loads and are connected to the DC bus through the corresponding H-Buck bidirectional DC-DC converters to transfer the electrical energy of the dischargeable electrical loads to the low-voltage distribution network or energy storage units. The unidirectional output DC ports are connected to the non-dischargeable electrical loads and are connected to the DC bus through the conversion branch, supplying power only to the non-dischargeable electrical loads in one direction.

[0009] Furthermore, a circuit breaker and a bidirectional AC-DC unit are sequentially connected between the port connected to the low-voltage distribution network and the DC bus, and the circuit breaker and the bidirectional AC-DC unit are connected to the local control center.

[0010] Furthermore, the circuit breaker uses an electronic fuse unit.

[0011] Furthermore, the control port connected to the photovoltaic unit is connected to an MPPT unit, and the MPPT unit is connected to the photovoltaic unit.

[0012] A control method using a low-voltage photovoltaic power router includes the following steps: Step 1: Obtain the energy storage status information, total power of electrical load, power generation of photovoltaic unit, and cloud control instructions or electricity grid connection price information of energy storage unit; Step 2: Determine the energy dispatch mode based on the comparison results between the cloud-based control instructions or the electricity grid connection price information and the preset electricity price threshold; Step 3: In energy dispatch mode, determine the energy flow direction based on the comparison between the photovoltaic unit's power generation, the energy storage unit's power supply capacity, and the total power of the electrical load.

[0013] Furthermore, step 2 is performed as follows: When the cloud-based control command or the electricity grid connection price information is greater than the preset electricity price threshold, the energy dispatch mode is determined to be the output mode; When the cloud-based control command or the electricity grid connection price information is less than or equal to the preset electricity price threshold, the energy dispatch mode is determined to be the input mode.

[0014] Furthermore, in output mode, the specific operation is as follows: Step 311: Determine whether the dischargeable electrical load is allowed to discharge. If the determination is yes, proceed to step 312; if the determination is no, proceed to step 313. Step 312: Determine whether the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 313; if the determination is no, proceed to step 314. Step 313: Power is supplied to the electrical loads from the dischargeable electrical loads first, and the surplus power is fed back to the low-voltage distribution network; Step 314: Determine whether the sum of the photovoltaic unit's power generation and the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 315; if the determination is no, proceed to step 316. Step 315: The photovoltaic unit and the dischargeable electrical load first supply power to the electrical load, and the surplus power feeds energy to the low-voltage distribution network. Step 316: Determine whether the power generation of the photovoltaic unit, the discharge power of the dischargeable electrical load, and the discharge power of the energy storage battery are greater than the total power of the electrical load. If the determination is yes, proceed to step 317; if the determination is no, proceed to step 318. Step 317: Power is supplied to the electrical load by the photovoltaic unit, the rechargeable and discharging electrical load, and the energy storage unit; Step 318: Power is supplied to the electrical load from the photovoltaic unit, the rechargeable and discharging electrical load, the energy storage unit, and the low-voltage distribution network.

[0015] Furthermore, in input mode, the specific operations are as follows: Step 321: Determine whether the dischargeable electrical load is allowed to discharge. If the determination is yes, proceed to step 322; if the determination is no, proceed to step 324. Step 322: Determine whether the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 323; if the determination is no, proceed to step 324. Step 323: Power is supplied to the electrical loads from the dischargeable electrical loads first, and the surplus power is stored in the energy storage unit; Step 324: Determine whether the sum of the photovoltaic unit's power generation and the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 325; if the determination is no, proceed to step 326. Step 325: The photovoltaic unit and the dischargeable electrical load first supply power to the electrical load, and the surplus power is stored in the energy storage unit; Step 326: Determine whether the power generation of the photovoltaic unit, the discharge power of the dischargeable electrical load, and the discharge power of the energy storage battery are greater than the total power of the electrical load. If the determination is yes, proceed to step 327; if the determination is no, proceed to step 328. Step 327: Power is supplied to the electrical load by the photovoltaic unit, the rechargeable and discharging electrical load, and the energy storage unit; Step 328: Power is supplied to the electrical load from the photovoltaic unit, the rechargeable and discharging electrical load, the energy storage unit, and the low-voltage distribution network.

[0016] Beneficial effects: Based on the characteristics of dischargeable electrical loads and a bidirectional converter, this invention enables power routers to dispatch power between local loads and feed surplus power into the grid, reducing reliance on renewable energy generation ports. Utilizing 4G wireless communication technology, it communicates with an external control center to aggregate real-time monitoring of charging and discharging power, temperature and humidity, and power flow management at each port, solving the problem of opaque charging and discharging data. Based on power generation and consumption data, it promptly adjusts the remaining battery capacity of the energy storage battery, ensuring future power reliability. This alleviates the power supply pressure on low-voltage distribution networks. The highly integrated "generation, storage, and consumption" system across multiple ports reduces line losses in power transmission between units, improves system efficiency and power density, and reduces the cost of transporting and installing separate units. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 This is a structural diagram of the low-voltage photovoltaic power router of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] The present invention will be further described below with reference to embodiments.

[0021] Example 1: Low-voltage photovoltaic power router, comprising: Local control center: Obtains energy storage status information, total power of electrical load, power generation of photovoltaic unit, and cloud control instructions or electricity grid connection price information from the power router. Based on the comparison between the cloud control instructions or electricity grid connection price information and the preset electricity price threshold, it determines the energy dispatch mode. Under the energy dispatch mode, it further determines the energy flow direction based on the comparison relationship between the power generation of photovoltaic unit, the power supply capacity of energy storage unit, and the total power of electrical load. Cloud-based control commands have higher priority than on-grid electricity prices. Energy storage unit: used to supply electrical energy and store excess electrical energy; The energy storage unit consists of an energy storage battery pack composed of energy storage cells and a battery management unit. The energy capacity of the energy storage unit can be configured according to the application of the router. Large-scale industrial and commercial energy storage systems are equipped with large-capacity energy storage units, while small-scale power generation, storage and utilization systems are equipped with small-capacity energy storage units. This is used to realize energy storage and regulate the power supply range of the low-voltage distribution network. The rated voltage of the energy storage battery pack is 48V, and it is connected to the DC bus through a DC-DC converter.

[0022] The three sets of external control ports are connected to the photovoltaic unit, the low-voltage distribution network, and the electrical load, respectively. The DC bus is electrically connected to the energy storage unit and the three sets of external control ports. The local control center is interconnected with the functional units on the DC bus side via communication.

[0023] Electrical loads include dischargeable electrical loads and non-dischargeable electrical loads; The control ports connected to the electrical load are bidirectional DC ports and unidirectional output DC ports. The bidirectional DC ports are connected to the dischargeable electrical loads and are connected to the DC bus through the corresponding H-Buck bidirectional DC-DC converter, transferring the electrical energy of the dischargeable electrical load to the low-voltage distribution network or energy storage unit. The unidirectional output DC ports are connected to the non-dischargeable electrical loads and are connected to the DC bus through the conversion branch, supplying power only to the non-dischargeable electrical load in one direction. A circuit breaker and a bidirectional AC-DC unit are connected sequentially between the port connected to the low-voltage distribution network and the DC bus. The circuit breaker and the bidirectional AC-DC unit are connected to the local control center. The circuit breaker uses an electronic fuse unit; The electronic fuse unit uses semiconductor switching devices such as MOSFET, SiC and IGBT in conjunction with a current monitoring unit (using a current sensing resistor or a current transformer) to monitor the direction and magnitude of the current. When an overcurrent occurs, the local control center controls the electronic fuse to trip. When the fault is cleared, the local control center controls the electronic fuse unit to resume conduction. When the low-voltage distribution network outputs power to the router, the local control center controls the bidirectional AC-DC unit to start, and the bidirectional AC-DC unit performs rectification and power factor correction. When power is fed back to the low-voltage distribution network, the local control center controls the bidirectional AC-DC unit to realize power inversion. The local control center identifies the reverse flow of power in real time and sends instructions to the bidirectional AC-DC unit to control the power to flow from the DC bus to the low-voltage distribution network. The control port connected to the photovoltaic unit is connected to an MPPT (maximum power point tracking) unit, and the MPPT unit is connected to the photovoltaic unit. The MPPT unit is externally mounted on the photovoltaic unit, with its output connected to the input of the power router; alternatively, it can be built into the power router to simplify the external installation process. The MPPT unit has the highest priority on the generation side and achieves maximum power point tracking of the photovoltaic system through control, maximizing the utilization of clean energy.

[0024] The DC bus is a stable DC bus with an operating voltage range of 800V~1200Vdc.

[0025] Example 2, based on Example 1, provides a control method using a low-voltage photovoltaic power router, comprising the following steps: Step 1: Obtain the energy storage status information, total power of electrical load, power generation of photovoltaic unit, and cloud control instructions or electricity grid connection price information of energy storage unit; Step 2: Determine the energy dispatch mode based on the comparison results between the cloud-based control instructions or the electricity grid connection price information and the preset electricity price threshold; Step 3: In energy dispatch mode, determine the energy flow direction based on the comparison between the photovoltaic unit's power generation, the energy storage unit's power supply capacity, and the total power of the electrical load.

[0026] Step 2 is performed as follows: When the cloud-based control command or the electricity grid connection price information is greater than the preset electricity price threshold, the energy dispatch mode is determined to be the output mode; When the cloud-based control command or the electricity grid connection price information is less than or equal to the preset electricity price threshold, the energy dispatch mode is determined to be the input mode.

[0027] In some embodiments, in output mode, the specific operation is as follows: Step 311: Determine whether the dischargeable electrical load is allowed to discharge. If the determination is yes, proceed to step 312; if the determination is no, proceed to step 313. Step 312: Determine whether the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 313; if the determination is no, proceed to step 314. Step 313: Power is supplied to the electrical loads from the dischargeable electrical loads first, and the surplus power is fed back to the low-voltage distribution network; Step 314: Determine whether the sum of the photovoltaic unit's power generation and the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 315; if the determination is no, proceed to step 316. Step 315: The photovoltaic unit and the dischargeable electrical load first supply power to the electrical load, and the surplus power feeds energy to the low-voltage distribution network. Step 316: Determine whether the power generation of the photovoltaic unit, the discharge power of the dischargeable electrical load, and the discharge power of the energy storage battery are greater than the total power of the electrical load. If the determination is yes, proceed to step 317; if the determination is no, proceed to step 318. Step 317: Power is supplied to the electrical load by the photovoltaic unit, the rechargeable and discharging electrical load, and the energy storage unit; Step 318: Power is supplied to the electrical load from the photovoltaic unit, the rechargeable and discharging electrical load, the energy storage unit, and the low-voltage distribution network.

[0028] Surplus power is the sum of the photovoltaic unit's power generation and the energy storage unit's power supply capacity minus the total power of the electrical load; In some embodiments, the specific operation in input mode is as follows: Step 321: Determine whether the dischargeable electrical load is allowed to discharge. If the determination is yes, proceed to step 322; if the determination is no, proceed to step 324. Step 322: Determine whether the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 323; if the determination is no, proceed to step 324. Step 323: Power is supplied to the electrical loads from the dischargeable electrical loads first, and the surplus power is stored in the energy storage unit; Step 324: Determine whether the sum of the photovoltaic unit's power generation and the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 325; if the determination is no, proceed to step 326. Step 325: The photovoltaic unit and the dischargeable electrical load first supply power to the electrical load, and the surplus power is stored in the energy storage unit. Step 326: Determine whether the power generation of the photovoltaic unit, the discharge power of the dischargeable electrical load, and the discharge power of the energy storage battery are greater than the total power of the electrical load. If the determination is yes, proceed to step 327; if the determination is no, proceed to step 328. Step 327: Power is supplied to the electrical load by the photovoltaic unit, the rechargeable and discharging electrical load, and the energy storage unit; Step 328: Power is supplied to the electrical load from the photovoltaic unit, the rechargeable and discharging electrical load, the energy storage unit, and the low-voltage distribution network.

[0029] Based on the characteristics of dischargeable electrical loads and a bidirectional converter, the power router enables power dispatching between local loads and grid connection of surplus power, reducing reliance on renewable energy generation ports. Utilizing 4G wireless communication technology, it communicates with an external control center to aggregate real-time monitoring of charging and discharging power, temperature and humidity, and power flow management at each port, resolving the issue of opaque charging and discharging data. Based on power generation and consumption data, it promptly adjusts the remaining battery capacity of the energy storage battery to ensure future power reliability. This alleviates the power supply pressure on low-voltage distribution networks. The highly integrated "generation, storage, and consumption" system across multiple ports reduces line losses in power transmission between units, improves system efficiency and power density, and reduces the costs of transporting and installing separate units.

[0030] Meanwhile, the circuit router can be combined with small-scale electrochemical energy storage for use in electric vehicle charging systems, enabling V2G and other functions. It can also be applied to industrial and commercial energy storage in remote areas to alleviate grid pressure. Furthermore, it is modular, intelligent, multifunctional, and highly integrated.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will 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.

Claims

1. A low-voltage photovoltaic power router, characterized in that: include: Local control center: Obtains energy storage status information, total power of electrical load, power generation of photovoltaic unit, and cloud control instructions or electricity grid connection price information from the power router. Based on the comparison between the cloud control instructions or electricity grid connection price information and the preset electricity price threshold, it determines the energy dispatch mode. Under the energy dispatch mode, it further determines the energy flow direction based on the comparison relationship between the power generation of photovoltaic unit, the power supply capacity of energy storage unit, and the total power of electrical load. Energy storage unit: used to supply electrical energy and store excess electrical energy; The three sets of external control ports are connected to the photovoltaic unit, the low-voltage distribution network, and the electrical load, respectively. The DC bus is electrically connected to the energy storage unit and the three sets of external control ports. The local control center is interconnected with the functional units on the DC bus side via communication.

2. The low-voltage photovoltaic power router according to claim 1, characterized in that, Electrical loads include dischargeable electrical loads and non-dischargeable electrical loads; The control ports connected to the electrical loads are bidirectional DC ports and unidirectional output DC ports. The bidirectional DC ports are connected to the dischargeable electrical loads and are connected to the DC bus through the corresponding H-Buck bidirectional DC-DC converters to transfer the electrical energy of the dischargeable electrical loads to the low-voltage distribution network or energy storage units. The unidirectional output DC ports are connected to the non-dischargeable electrical loads and are connected to the DC bus through the conversion branch, supplying power only to the non-dischargeable electrical loads in one direction.

3. The low-voltage photovoltaic power router according to claim 2, characterized in that, A circuit breaker and a bidirectional AC-DC unit are connected sequentially between the port connected to the low-voltage distribution network and the DC bus. The circuit breaker and the bidirectional AC-DC unit are connected to the local control center.

4. The low-voltage photovoltaic power router according to claim 3, characterized in that, The circuit breaker uses an electronic fuse unit.

5. The low-voltage photovoltaic power router according to claim 4, characterized in that, The control port connected to the photovoltaic unit is connected to the MPPT unit, and the MPPT unit is connected to the photovoltaic unit.

6. A control method, employing a low-voltage photovoltaic power router according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Obtain the energy storage status information, total power of electrical load, power generation of photovoltaic unit, and cloud control instructions or electricity grid connection price information of energy storage unit; Step 2: Determine the energy dispatch mode based on the comparison results between the cloud-based control instructions or the electricity grid connection price information and the preset electricity price threshold; Step 3: In energy dispatch mode, determine the energy flow direction based on the comparison between the photovoltaic unit's power generation, the energy storage unit's power supply capacity, and the total power of the electrical load.

7. The control method according to claim 6, characterized in that, Step 2 is performed as follows: When the cloud-based control command or the electricity grid connection price information is greater than the preset electricity price threshold, the energy dispatch mode is determined to be the output mode; When the cloud-based control command or the electricity grid connection price information is less than or equal to the preset electricity price threshold, the energy dispatch mode is determined to be the input mode.

8. The control method according to claim 7, characterized in that, In output mode, the specific operation is as follows: Step 311: Determine whether the dischargeable electrical load is allowed to discharge. If the determination is yes, proceed to step 312; if the determination is no, proceed to step 313. Step 312: Determine whether the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 313; if the determination is no, proceed to step 314. Step 313: Power is supplied to the electrical loads from the dischargeable electrical loads first, and the surplus power is fed back to the low-voltage distribution network; Step 314: Determine whether the sum of the photovoltaic unit's power generation and the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 315; if the determination is no, proceed to step 316. Step 315: The photovoltaic unit and the dischargeable electrical load first supply power to the electrical load, and the surplus power feeds energy to the low-voltage distribution network. Step 316: Determine whether the power generation of the photovoltaic unit, the discharge power of the dischargeable electrical load, and the discharge power of the energy storage battery are greater than the total power of the electrical load. If the determination is yes, proceed to step 317; if the determination is no, proceed to step 318. Step 317: Power is supplied to the electrical load by the photovoltaic unit, the rechargeable and discharging electrical load, and the energy storage unit; Step 318: Power is supplied to the electrical load from the photovoltaic unit, the rechargeable and discharging electrical load, the energy storage unit, and the low-voltage distribution network.

9. The control method according to claim 7, characterized in that, In input mode, the specific operation is as follows: Step 321: Determine whether the dischargeable electrical load is allowed to discharge. If the determination is yes, proceed to step 322; if the determination is no, proceed to step 324. Step 322: Determine whether the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 323; if the determination is no, proceed to step 324. Step 323: Power is supplied to the electrical loads from the dischargeable electrical loads first, and the surplus power is stored in the energy storage unit; Step 324: Determine whether the sum of the photovoltaic unit's power generation and the discharge power of the dischargeable electrical load is greater than the total power of the electrical load. If the determination is yes, proceed to step 325; if the determination is no, proceed to step 326. Step 325: The photovoltaic unit and the dischargeable electrical load first supply power to the electrical load, and the surplus power is stored in the energy storage unit; Step 326: Determine whether the power generation of the photovoltaic unit, the discharge power of the dischargeable electrical load, and the discharge power of the energy storage battery are greater than the total power of the electrical load. If the determination is yes, proceed to step 327; if the determination is no, proceed to step 328. Step 327: Power is supplied to the electrical load by the photovoltaic unit, the rechargeable and discharging electrical load, and the energy storage unit; Step 328: Power is supplied to the electrical load from the photovoltaic unit, the rechargeable and discharging electrical load, the energy storage unit, and the low-voltage distribution network.

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