Grid-connected and off-grid switching system

Abstract

The invention relates to a grid-connected and off-grid switching system. The grid-connected and off-grid switching system comprises a controller, a static change-over switch, a grid-connected contactor, a power grid circuit breaker and a load power supply switch assembly, the static change-over switch obtains the voltage of the power grid and the energy storage equipment group and supplies the voltage to the first load and the controller; the load power supply switch assembly obtains the voltage of the power grid through the grid-connected contactor, directly obtains the voltage of the energy storage equipment group, and supplies the voltage to the second load. And the controller controls the static change-over switch, the grid-connected contactor and the load power supply switch assembly to work, so that a working mode is switched to a grid-connected mode and power is supplied through the power grid or the energy storage equipment group, and the working mode is switched to an off-grid mode and power is supplied through the energy storage equipment group. For the scene of large power consumption change, the load with low power supply priority is subjected to grid-connected and off-grid switching through the contactor, the input cost is reduced, the load with high power supply priority and core loads such as the controller are low in power level, switching is still achieved through the static change-over switch, and the power supply continuity is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of power grid control technology, and in particular to a grid-connected and off-grid switching system. Background Art

[0002] With the increasing penetration of renewable energy and the rapid development of microgrid technology, seamless on-grid and off-grid switching has become a core requirement for ensuring grid reliability and efficient energy utilization, especially in areas such as data centers, medical facilities, and industrial automation, where power continuity is paramount. Current switching methods often rely on static transfer switches (STSs) to achieve fast, seamless switching between two independent power sources.

[0003] However, static transfer switches require semiconductor devices such as high-speed thyristors (SCRs) to achieve contactless switching. These devices must possess high voltage resistance, high current carrying capacity, and low conduction losses, resulting in significantly higher unit costs than traditional mechanical switches. For example, STS modules with power ratings above 200kW can cost tens of thousands of yuan, and the cost increases exponentially when multiple units are connected in parallel. Therefore, using static transfer switches to implement power switching in scenarios with large power consumption fluctuations is prohibitively expensive. Summary of the Invention

[0004] Based on this, it is necessary to provide an on-grid and off-grid switching system to address the technical problem of excessive investment cost in implementing power supply switching using static transfer switches.

[0005] A grid-connected and off-grid switching system includes a controller, and a static transfer switch, a grid-connected contactor, a grid circuit breaker, and a load power supply switch assembly connected to the controller;

[0006] The first power-taking end of the static transfer switch is connected to the grid through the grid circuit breaker, the second power-taking end of the static transfer switch is connected to the energy storage device group, and the power-supply end of the static transfer switch is connected to the first load and the controller;

[0007] The power-taking end of the load power supply switch assembly is connected to the power grid through the grid-connected contactor and the grid circuit breaker in sequence, the power-taking end is connected to the energy storage device group, the power-supply end of the load power supply switch assembly is connected to a second load, and the energy storage device group is connected to the power grid through the grid-connected contactor and the grid circuit breaker in sequence, and the power supply priority of the first load is higher than that of the second load;

[0008] The controller is used to control the operation of the static transfer switch, the grid-connected contactor and the load power supply switch assembly, so as to switch the working mode to the grid-connected mode and supply power through the power grid or the energy storage device group, and to switch the working mode to the off-grid mode and supply power through the energy storage device group.

[0009] In one embodiment,

[0010] When the operating mode needs to be switched to the off-grid mode, the controller determines a target switching mode according to the first on / off state of the grid-connected contactor and the power supply state of the grid, thereby switching the operating mode to the off-grid mode.

[0011] In one embodiment,

[0012] The controller determines that the target switching mode is active grid connection and disconnection when the first switching state is a closed state and the power supply state of the grid is a normal state;

[0013] The controller determines that the target switching mode is passive grid connection and disconnection when the first switching state is a closed state and the power supply state of the power grid is an abnormal state;

[0014] When the first switching state is the open state, the controller determines that the target switching mode is to directly disconnect from the grid.

[0015] In one embodiment,

[0016] When the target switching mode is active grid connection and disconnection, the controller first controls the load power supply switch assembly to operate, controls the target power supply end of the static transfer switch to be the second power supply end, supplies power through the energy storage device group, and then controls the grid-connected contactor to be in an off state;

[0017] When the target switching mode is passive grid connection and disconnection, the controller controls the grid contactor to be in an off state, and controls the load power supply switch assembly to operate, so as to supply power through the energy storage device group;

[0018] When the target switching mode is direct disconnection from the grid, the controller controls the load power supply switch component to operate and supply power through the energy storage device group.

[0019] In one embodiment,

[0020] When the operating mode needs to be switched to the grid-connected mode and the second opening and closing state of the grid circuit breaker is the closed state, the controller controls the grid-connected contactor and the load power supply switch assembly to be in the closed state, thereby switching the operating mode to the grid-connected mode.

[0021] In one embodiment,

[0022] When the working mode is the grid-connected mode and is in a preset peak time period, the controller controls the target power-taking end of the static transfer switch to be the second power-taking end, the grid-connected contactor and the load power supply switch assembly to be in a closed state, and power is supplied through the energy storage device group;

[0023] When the working mode is the grid-connected mode and is in a preset valley time period, the controller controls the target power supply end of the static transfer switch to be the first power supply end, the grid-connected contactor and the load power supply switch assembly to be in a closed state, and power is supplied through the power grid.

[0024] In one embodiment, a switch is further included, the switch being connected to the power supply end of the static transfer switch, and the energy storage device group communicates with the controller through the switch to feedback the remaining power status of the energy storage device group;

[0025] The second load includes multiple types of sub-loads with descending power supply priorities, the load power supply switch assembly includes load power supply switches matching the number of the sub-loads, and each of the sub-loads obtains power through a corresponding load power supply switch;

[0026] The controller is used to determine the target power supply priority according to the power supply gear to which the remaining power status belongs, and control the opening and closing state of the corresponding load power supply switch based on the target power supply priority to realize power supply through the energy storage device group.

[0027] In one embodiment, it further includes a power consumption monitoring module connected to the controller;

[0028] The power consumption monitoring module is configured to monitor and obtain the first power consumption corresponding to the controller, the switch, and the first load, and to monitor and obtain the sub-power consumption corresponding to each of the sub-loads;

[0029] The controller is used to control the output power value of the energy storage device group according to the first power consumption and each of the sub-power consumptions.

[0030] In one embodiment,

[0031] The controller controls the energy storage device group to discharge to the power grid when the working mode is the grid-connected mode and the power supply level to which the remaining power level of the energy storage device group belongs is the highest power supply level.

[0032] In one embodiment,

[0033] When the energy storage device group includes a low-power energy storage device whose remaining power state is lower than a preset power threshold, the controller switches the working mode to the grid-connected mode and controls the charging of the low-power energy storage device through the power grid.

[0034] The above-mentioned on-grid and off-grid switching system includes a controller and a static transfer switch, a grid contactor, a grid circuit breaker and a load power supply switch assembly connected to the controller; the first power-taking end of the static transfer switch is connected to the grid through the grid circuit breaker, the second power-taking end of the static transfer switch is connected to the energy storage device group, and the power supply end of the static transfer switch is connected to the first load and the controller; the power-taking end of the load power supply switch assembly is connected to the grid through the grid contactor and the grid circuit breaker in turn, the power-taking end of the load power supply switch assembly is connected to the energy storage device group, the power supply end of the load power supply switch assembly is connected to the second load, and the energy storage device group is connected to the grid through the grid contactor and the grid circuit breaker in turn, and the power supply priority of the first load is higher than that of the second load; the controller is used to control the operation of the static transfer switch, the grid contactor and the load power supply switch assembly to realize switching the working mode to the grid-connected mode, supplying power through the grid or the energy storage device group, and switching the working mode to the off-grid mode, supplying power through the energy storage device group. For scenarios with large fluctuations in power consumption, AC contactors are used to switch loads with low power supply priority between on-grid and off-grid, greatly reducing investment costs. At the same time, core loads such as loads with high power supply priority and controllers have lower power levels and can still be switched between on-grid and off-grid through static transfer switches, which can also ensure power supply continuity at a lower cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following briefly introduces the drawings required for use in the embodiments of the present application or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic diagram of a system block diagram of an on-grid and off-grid switching system in one embodiment;

[0037] Figure 2 A schematic diagram of a system block diagram of an energy storage device in one embodiment;

[0038] Figure 3A schematic diagram of a system block diagram of an on-grid and off-grid switching system in another embodiment;

[0039] Figure 4 Schematic diagram of communication connection of a controller in one embodiment;

[0040] Figure 5 Schematic diagram of a flow chart of a method for switching between on-grid and off-grid in one embodiment;

[0041] Figure 6 FIG. 4 is a flow chart of a power supply method in an embodiment. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0043] In an exemplary embodiment, Figure 1 As shown, a grid-connected and off-grid switching system is provided, comprising a controller 110, and a static transfer switch 120, a grid-connected contactor 130, a grid circuit breaker 140, and a load power supply switch assembly 150 connected to the controller 110; a first power-taking end of the static transfer switch 120 is connected to the grid through the grid circuit breaker 140, a second power-taking end of the static transfer switch 120 is connected to the energy storage device group 20, a power-supply end of the static transfer switch 120 is connected to the first load and the controller 110; a power-taking end of the load power supply switch assembly 150 is connected to the grid circuit breaker 140 in sequence through the grid-connected contactor 130. 0 is connected to the grid, the power-taking end is connected to the energy storage device group 20, the power-supply end of the load power supply switch assembly 150 is connected to the second load, and the energy storage device group 20 is connected to the grid in sequence through the grid contactor 130 and the grid circuit breaker 140. The power supply priority of the first load is higher than that of the second load; the controller 110 is used to control the operation of the static transfer switch 120, the grid contactor 130 and the load power supply switch assembly 150 to switch the working mode to the grid-connected mode and supply power through the grid or the energy storage device group 20, and to switch the working mode to the off-grid mode and supply power through the energy storage device group 20.

[0044] The energy storage device group 20 includes multiple energy storage devices connected in parallel, such as Figure 2 As shown, each energy storage device can include battery modules, a battery management system (BMS), an energy management system (EMS), a bidirectional inverter (PCS), and circuit breakers. It can serve as a backup power source for various technical areas, ensuring that critical production equipment continues to operate and production continuity in the event of a grid failure or power outage.

[0045] Specifically, the static transfer switch 120 is used to switch between the first load and core loads, such as the controller 110, on and off the grid. It is understood that the static transfer switch 120 is a power protection device used for rapid and uninterrupted switching between two independent power sources. It utilizes semiconductor devices, such as high-speed thyristors (SCRs), to achieve contactless switching. These devices must possess high voltage resistance, high current carrying capacity, and low conduction loss. Furthermore, the static transfer switch 120 continuously monitors electrical parameters, such as voltage, frequency, and phase, at its first and second power terminals. If a fault occurs at either terminal (such as voltage anomalies, frequency deviation, or phase loss), the static transfer switch 120 automatically switches to the normal power terminal within milliseconds (typically ≤8ms).

[0046] Correspondingly, the first power-taking end of the static transfer switch 120 provided in this application is connected to the grid through the grid circuit breaker 140 , the second power-taking end is connected to the energy storage device group 20 , and the power-supply end is connected to the first load and the controller 110 .

[0047] It can be understood that if the static transfer switch 120 uses the grid connected to its first power-taking end as the main power source, the voltage of the grid obtained from the first power-taking end is sent to the power-supply end, and then output from the power-supply end to the first load and the controller 110 for power supply. In addition, the electrical parameters of the grid connected to the first power-taking end are continuously monitored. When a grid failure occurs, it can automatically switch to obtaining the voltage of the energy storage device group 20 from the second power-taking end within milliseconds, send it to the power-supply end, and then output from the power-supply end to the first load and the controller 110 for power supply. Furthermore, when the grid power returns to normal, the static transfer switch 120 can automatically switch back to obtaining the voltage of the grid from the first power-taking end, and then output from the power-supply end to the first load and the controller 110 for power supply.

[0048] It can be understood that this application will realize power supply switching for the first load with higher power supply priority and core loads such as the controller 110 through the static transfer switch 120, ensuring that in the event of a power grid failure or power outage, uninterrupted power switching can be achieved through the static transfer switch 120, and key core electrical equipment can continue to operate, ensuring power continuity.

[0049] Furthermore, for the second load having a lower power supply priority than the first load, the present application designs a grid-connected contactor 130 for on-grid and off-grid switching, which can greatly reduce investment costs in scenarios where power consumption varies greatly.

[0050] Among them, the power-taking end of the load power supply switch assembly 150 is connected to the power grid through the grid contactor 130 and the grid circuit breaker 140 in turn. The power-taking end is also connected to the energy storage device group 20. The power-supply end of the load power supply switch assembly 150 is connected to the second load to realize the power supply line for the second load. When the grid circuit breaker 140 is in a closed state, it indicates that the power grid is in a normal operating state. Then, when the grid contactor 130 is in a closed state, the second load can be powered by the power grid. When the grid contactor 130 is in a closed state, the second load can also be powered by the energy storage device group 20 connected to the power-taking end of the load power supply switch assembly 150.

[0051] It is understood that the operating modes of the on-grid and off-grid switching system can include on-grid mode and off-grid mode. The on-grid mode connects the energy storage device to the public grid, enabling bidirectional power flow and coordinated operation. The corresponding off-grid mode is when the energy storage device operates independently of the public grid to meet the power needs of a specific area or user.

[0052] Furthermore, the present application can connect the controller 110 to the static transfer switch 120, the grid contactor 130, the grid circuit breaker 140, and the load power supply switch assembly 150, and control the operation of the static transfer switch 120, the grid contactor 130, and the load power supply switch assembly 150 to achieve on-grid and off-grid switching. For example, the operating mode can be switched to on-grid mode, with power supplied by the grid or the energy storage device group 20, and the operating mode can be switched to off-grid mode, with power supplied by the energy storage device group 20.

[0053] Among them, controlling the operation of the static transfer switch 120, the grid-connected contactor 130 and the load power supply switch assembly 150 may refer to switching the target power supply end of the static transfer switch 120 between the first power supply end and the second power supply end, or may refer to switching the first opening and closing state of the grid-connected contactor 130 between the closed state and the open state, or may refer to switching the opening and closing state of the load power supply switch assembly 150 between the closed state and the open state.

[0054] In addition, the energy storage device group 20 can also be connected to the power grid through the grid contactor 130 and the grid circuit breaker 140 in sequence, so as to charge the low-power energy storage devices in the energy storage device group 20 whose remaining power status is lower than the preset power threshold through the power grid to ensure that the energy storage device group 20 has sufficient power.

[0055] The above-mentioned on-grid and off-grid power supply switching system uses AC contactors to switch loads with low power supply priority on and off the grid in scenarios with large changes in power consumption, greatly reducing investment costs. At the same time, core loads such as loads with high power supply priority and controllers have lower power levels and can still achieve on-grid and off-grid switching through static transfer switches, which can also ensure power supply continuity at a lower cost.

[0056] In an exemplary embodiment, when the operating mode needs to be switched to the off-grid mode, the controller determines the target switching mode according to the first open / close state of the grid-connected contactor and the power supply state of the grid to switch the operating mode to the off-grid mode.

[0057] Specifically, the need to switch to off-grid mode may arise from switching from grid-connected mode to off-grid mode, or it may arise from a power-on instruction requiring off-grid operation. Switching from grid-connected mode to off-grid mode may occur due to an unplanned power outage caused by a grid fault, or it may arise from receiving a control instruction to switch from grid-connected mode to off-grid mode.

[0058] Furthermore, when the controller needs to switch the working mode to the off-grid mode, it must first determine which of the above-mentioned switching scenarios it belongs to based on the first opening and closing state of the grid-connected contactor and the power supply status of the power grid and other status data, and then determine the target switching method to achieve safe and reliable switching of the working mode to the off-grid mode.

[0059] Correspondingly, in some embodiments, when the first switching state of the grid-connected contactor is the closed state and the power supply state of the grid is normal, the controller determines that the target switching mode is active grid connection and disconnection.

[0060] It can be understood that if the first opening and closing state of the grid-connected contactor is closed, the system's operating mode before the switching action was grid-connected mode, and the switching scenario at this time should be switching from grid-connected mode to off-grid mode. Furthermore, if the power supply status of the grid is normal, it may indicate that a control instruction has been received to actively switch from grid-connected mode to off-grid mode. Therefore, the controller can determine the target switching mode as active grid-connected and off-grid when the first opening and closing state of the grid-connected contactor is closed and the power supply status of the grid is normal.

[0061] Correspondingly, in some embodiments, when the first switching state of the grid-connected contactor is the closed state and the power supply state of the grid is an abnormal state, the controller determines that the target switching mode is passive grid connection and disconnection.

[0062] It can be understood that the first opening and closing state of the grid contactor is closed, indicating that the system's operating mode before the switching action was grid-connected mode. The switching scenario at this time should also be switching from grid-connected mode to off-grid mode. Furthermore, if the power supply status of the grid is abnormal, this may indicate an unplanned power outage due to a fault. Therefore, if the first opening and closing state of the grid contactor is closed and the power supply status of the grid is abnormal, the controller can determine the target switching mode as passive grid-connected disconnection.

[0063] Correspondingly, in some embodiments, the controller determines the target switching mode as direct grid disconnection when the first on / off state of the grid-connected contactor is in the disconnected state. This can be understood as indicating that the first on / off state of the grid-connected contactor is in the disconnected state, indicating that the system is in a state of recent power-up and requires off-grid operation before the switching action. Consequently, the controller may determine the target switching mode as direct grid disconnection.

[0064] After determining the target switching mode, the static transfer switch, grid-connected contactor and load power supply switch components can be controlled in the corresponding manner to achieve safe and reliable switching from the working mode to the off-grid mode.

[0065] In an exemplary embodiment, when the target switching mode is active grid connection and disconnection, the controller first controls the load power supply switch component to operate, and controls the target power supply end of the static transfer switch to be the second power supply end, supplies power through the energy storage device group, and then controls the grid-connected contactor to be in the disconnected state.

[0066] Specifically, the target switching mode is active grid connection and disconnection, indicating that the grid is operating normally before the switching action. The load power supply switch assembly can then be controlled to operate, powering the second load via the energy storage device group. Simultaneously, the static transfer switch's target power supply terminal can be controlled to the second power supply terminal, powering the first load and the controller via the energy storage device group. After both loads are powered normally, the grid contactor is controlled to disconnect, achieving the switch from grid-connected mode to off-grid mode.

[0067] With this design, when actively connecting to the grid and disconnecting from the grid, a grid contactor disconnection command is issued to control the grid contactor to be in the disconnected state before the energy storage device group is synchronously powered to ensure continuous power supply.

[0068] In an exemplary embodiment, when the target switching mode is passive grid connection and disconnection, the controller controls the grid contactor to be in an open state, and controls the load power supply switch assembly to operate, and supplies power through the energy storage device group.

[0069] Specifically, the target switching mode is passive grid connection and disconnection, which indicates that the power grid is in a fault state before the switching action. In this case, the static transfer switch will automatically switch the target power supply end to the second power supply end to achieve uninterrupted power supply to the first load and the controller.

[0070] Furthermore, if the target switching mode is passive grid-connection / off-grid disconnection, and the grid power supply is abnormal, possibly due to an unplanned outage caused by a fault, the controller can directly control the grid contactor to open without waiting for the energy storage device group to synchronize power. Simultaneously, the controller controls the load power supply switch assembly to operate, powering the second load through the energy storage device group, achieving the switch from grid-connected mode to off-grid mode.

[0071] With this design, in scenarios with large fluctuations in power consumption, loads with low power supply priority can be switched to off-grid mode using AC contactors, greatly reducing investment costs. At the same time, core loads such as loads with high power supply priority and controllers, which have lower power levels, can still be switched to off-grid mode using static transfer switches, ensuring power supply continuity at a lower cost.

[0072] In an exemplary embodiment, when the target switching mode is direct disconnection from the grid, the controller controls the load power supply switch component to operate and supply power through the energy storage device group.

[0073] Specifically, the target switching mode is direct disconnection from the grid, which indicates that before this switching action, the system is in the state of just starting up and powering on, indicating that it needs to enter the off-grid mode. Then, the controller can directly control the operation of the load power supply switch component to power the second load through the energy storage device group.

[0074] The power supply switching method for the first load and the controller can also be determined based on the power supply status of the power grid. If the power supply status of the power grid is abnormal, the static transfer switch can automatically switch the target power source to the second power source, eliminating the need for the controller to control the operation of the static transfer switch. If the power supply status of the power grid is normal, the controller can control the static transfer switch to switch the target power source to the second power source, thereby powering the first load and the controller through the energy storage device group.

[0075] In an exemplary embodiment, when the working mode needs to be switched to the grid-connected mode and the second opening and closing state of the grid circuit breaker is in the closed state, the controller controls the grid-connected contactor and the load power supply switch assembly to be in the closed state, thereby switching the working mode to the grid-connected mode.

[0076] The system indicates that the operating mode needs to be switched to grid-connected mode, indicating that the energy storage device needs to be connected to the public grid to achieve two-way power flow and coordinated operation. This scenario may indicate that power demand requires power to be supplied by the energy storage device group and the grid, or it may indicate that the energy storage device group needs to charge its low-power energy storage device through the grid.

[0077] Specifically, when the controller needs to switch the operating mode to grid-connected mode, it must first confirm that the second open / close state of the grid circuit breaker is closed, thereby ensuring that the grid power supply is normal. If all of these conditions are met, the controller can then control the grid contactor to close, switching the operating mode to grid-connected mode. Simultaneously, the controller controls the load power supply switch assembly to close, enabling power to be supplied to the second load via the energy storage device group or the grid.

[0078] In grid-connected mode, in order to optimize energy utilization and improve power supply economy and energy utilization efficiency, the controller can use the peak-valley electricity price difference of the power grid to control the operation of the static transfer switch, grid-connected contactor and load power supply switch components to achieve power supply switching between the energy storage device group and the power grid.

[0079] Correspondingly, in some embodiments, when the operating mode is grid-connected mode and is in a preset peak time period, the controller controls the static transfer switch to have its target power supply terminal at the second power supply terminal, the grid-connected contactor and the load power supply switch assembly to be in a closed state, and power is supplied through the energy storage device group. In some embodiments, when the operating mode is grid-connected mode and is in a preset valley time period, the controller controls the static transfer switch to have its target power supply terminal at the first power supply terminal, the grid-connected contactor and the load power supply switch assembly to be in a closed state, and power is supplied through the grid.

[0080] The preset peak time period is the peak electricity consumption period, during which electricity prices may be higher due to peak electricity consumption. Correspondingly, the preset valley time period is the low electricity consumption period, during which electricity prices are lower. Based on the significant volatility and seasonality of electricity demand, power supply switching between peak and valley periods can be implemented in the grid-connected mode to reduce electricity costs for power supply recipients while improving energy efficiency.

[0081] Specifically, when operating in grid-connected mode and during a preset peak time period, the controller can control the static transfer switch to target the second power source, powering the first load and the controller via the energy storage device group. Simultaneously, the load power supply switch assembly remains closed, and the power source of the load power supply switch assembly draws power from the energy storage device group, thereby powering the second load via the energy storage device group. It can be understood that switching to power supply via the energy storage device group during the preset peak time period can reduce electricity costs during peak periods.

[0082] Furthermore, when the operating mode is grid-connected and during a preset off-peak period, the controller can control the static transfer switch to target the first power terminal, thereby powering the first load and the controller via the grid. Simultaneously, the grid-connected contactor and the load power supply switch assembly remain closed, and the power terminal of the load power supply switch assembly draws power from the grid, thereby powering the second load via the grid. It can be understood that switching to grid power during the preset off-peak period ensures that power is delivered at a lower cost during periods of low electricity prices.

[0083] Furthermore, when operating in grid-connected mode and during a preset peak period, the energy storage device group can also release stored energy back to the grid via the grid-connected contactor using its internal bidirectional current converter (PCS), thereby generating a certain profit during periods of higher electricity prices and further reducing electricity costs. Similarly, when operating in grid-connected mode and during a preset off-peak period, the controller can control the grid-connected contactor to charge the energy storage device group and store energy.

[0084] Among them, the specific settings of the preset peak time period and the preset valley time period are not limited. The controller can predict electricity price fluctuations and load demand changes by recording historical electricity consumption data, and then set appropriate preset peak time periods and preset valley time periods to achieve the purpose of improving power supply economy and energy utilization efficiency. In actual applications, the occurrence of peak time periods is often related to factors such as industrial electricity consumption peaks and concentrated residential electricity consumption periods (such as summer air conditioning electricity consumption peaks), while valley time periods usually occur at night or in the early morning when industrial electricity consumption decreases and residential electricity demand decreases. Therefore, in some examples, the preset peak time period can be set to daytime, and the preset valley time period can be set to late at night.

[0085] In an exemplary embodiment, the above-mentioned on-grid and off-grid switching system also includes a switch, which is connected to the power transmission end of the static transfer switch. The energy storage device group communicates with the controller through the switch to feedback the remaining power status of the energy storage device group; the second load includes multiple types of sub-loads with decreasing power supply priorities, and the load power supply switch assembly includes load power supply switches that match the number of sub-loads, and each sub-load obtains power through a load power supply switch; the controller is used to determine the target power supply priority according to the power supply gear to which the remaining power status belongs, and control the opening and closing state of the corresponding load power supply switch based on the target power supply priority to realize power supply through the energy storage device group.

[0086] Specifically, the battery management system (BMS) in each energy storage device in the energy storage device group can communicate with the controller through the switch to feed back its remaining power status to the controller so that the controller can obtain the remaining power status of the energy storage device group.

[0087] Among them, the switch can also be connected to the power supply end of the static transfer switch. Like the controller, it serves as a core load and achieves uninterrupted power supply through the static transfer switch.

[0088] Furthermore, the second load may include multiple types of sub-loads with decreasing power supply priorities, and the load power supply switch component includes load power supply switches that match the number of sub-loads, and each sub-load obtains power through a corresponding load power supply switch. Taking the example of the second load including two types of sub-loads, it may include a first sub-load and a second sub-load, and the power supply priority of the first sub-load is higher than that of the second sub-load. Correspondingly, the load power supply switch component also includes load power supply switches that are consistent with the number of sub-loads, such as a first load power supply switch and a second load power supply switch. Then the connection relationship can be that the first sub-load obtains power through the first load power supply switch, and the second sub-load obtains power through the second load power supply switch. Of course, the load power supply switches in the load power supply switch component can also be redundantly set, for example, including load power supply switches that are twice the number of sub-loads, to achieve more reliable power supply.

[0089] When the system includes a first load and multiple sub-loads with decreasing power supply priorities, it indicates that there are multiple power supply priorities. In order to improve power usage flexibility, the controller can perform load regulation based on the power supply priorities and plan power distribution resources.

[0090] Correspondingly, when power is supplied by the energy storage device group, the controller can divide the energy storage device group's energy storage capacity into multiple power supply levels and determine which loads of different power supply priorities can be supplied by each power supply level. The controller then determines the target power supply priority based on the remaining power level. Loads that fall within the target power supply priority level are controlled to have their corresponding load power switches closed, while those that do not fall within the target power supply priority level are controlled to have their corresponding load power switches open, thus achieving load control.

[0091] It can be understood that in order to ensure the power supply continuity of the core load, each power supply level needs to supply power to it. Therefore, the power supply priority of the core load always belongs to the target power supply priority, and the operation of the static switching switch does not need to be controlled. This embodiment can only consider controlling the opening and closing state of the load power supply switch to achieve load regulation.

[0092] Taking the first power supply gear, the second power supply gear, the third power supply gear and the fourth power supply gear as an example, from the first power supply gear to the fourth power supply gear, the remaining power state of the energy storage device group decreases in sequence. The power supply priority of the core loads such as the first load, controller and switch is set to the first priority, the power supply priority of the first sub-load is set to the second priority, and the power supply priority of the second sub-load is set to the third priority. From the first priority to the third priority, the level decreases in sequence. Correspondingly, it can be set that in the first power supply gear and the second power supply gear, power can be supplied to loads of all power supply priorities; in the third power supply gear, only power can be supplied to loads of the first priority and the second priority; in the fourth power supply gear, only power can be supplied to loads of the first priority.

[0093] Furthermore, in actual application, if the power supply gear to which the remaining power state of the energy storage device group belongs is the first power supply gear and the second power supply gear, it can be determined that the target priority includes the second priority and the third priority, and the load power supply switches corresponding to the loads of the second priority and the third priority can be controlled to be in a closed state. If the power supply gear to which the remaining power state of the energy storage device group belongs is the third power supply gear, it can be determined that the target priority includes the second priority, and the load power supply switches corresponding to the loads of the second priority are controlled to be in a closed state, and the load power supply switches corresponding to the loads of the third priority are in an open state. If the power supply gear to which the remaining power state of the energy storage device group belongs is the fourth power supply gear, it can be determined that the target priority includes only the first priority, and the load power supply switches corresponding to the loads of the second priority and the third priority are controlled to be in an open state.

[0094] In an exemplary embodiment, the above-mentioned on-grid and off-grid switching system also includes a power consumption monitoring module connected to the controller; the power consumption monitoring module is used to monitor and obtain the first power consumption corresponding to the controller, the switch and the first load, and monitor the sub-power consumption corresponding to each sub-load; the controller is used to control the output power value of the energy storage device group according to the first power consumption and each sub-power consumption.

[0095] Specifically, the controller can communicate with the internal bidirectional converter (PCS) of the energy storage device group through the switch to control the output power value of each energy storage device, and then control the output power value of the entire energy storage device group.

[0096] The power consumption monitoring module can be implemented using an electric meter. The electric meter can monitor the power consumption of the corresponding load in real time through built-in sensors, collecting parameters such as voltage, current, power, and power consumption. The power consumption monitoring module can specifically include multiple load electric meters. For example, one load electric meter can monitor the first power consumption corresponding to the controller, switch, and first load, and multiple load electric meters can monitor the sub-power consumption corresponding to each sub-load.

[0097] Furthermore, in the process of the controller performing load regulation based on power supply priority, the energy storage device group can be controlled to output an output power value corresponding to the above-mentioned power demand based on the first power consumption and the sub-power consumption of the sub-load belonging to the target power supply priority to improve energy utilization efficiency.

[0098] In some embodiments, the controller can also configure power usage limits for the load meters. When a load meter detects that the power usage of its connected load exceeds the set power usage limit, the load meter can provide a power usage limit alarm to the controller, causing the controller to disconnect the corresponding load power switch. This design allows the controller to cut off power to non-critical loads, preventing the energy storage device from running low on remaining power and causing over-discharge of the battery.

[0099] In an exemplary embodiment, when the working mode is the grid-connected mode and the power supply level of the remaining power state of the energy storage device group is the highest power supply level, the controller controls the energy storage device group to discharge to the grid.

[0100] Specifically, when the operating mode is grid-connected and the energy storage device group's remaining power level is at the highest power level, the energy storage device group has sufficient power. At this point, the controller, using the bidirectional current converter (PCS) within the energy storage device group, controls the release of excess power to the grid via the grid-connected contactor, thereby generating a certain amount of discharge revenue and reducing electricity costs.

[0101] In an exemplary embodiment, when the energy storage device group includes a low-power energy storage device whose remaining power state is lower than a preset power threshold, the controller switches the working mode to the grid-connected mode and controls the charging of the low-power energy storage device through the power grid.

[0102] The preset power threshold is a value indicating a low remaining power level of the energy storage device. This embodiment is not limited thereto and may be set based on actual technical requirements. For example, in some embodiments, it may be set to 20%. When the remaining power level of the energy storage device is lower than the preset power threshold, it indicates that the energy stored in the energy storage device is about to be depleted and needs to be charged as soon as possible.

[0103] Specifically, the controller communicates with the battery management system (BMS) in each energy storage device through the switch to obtain the remaining power threshold of each energy storage device. If it detects that the remaining power of a low-power energy storage device in the energy storage device group is below a preset power threshold, the controller can control the system to switch to grid-connected mode and charge the low-power energy storage device through the power grid.

[0104] In an exemplary embodiment, the on-grid and off-grid switching system further includes an interactive component connected to the controller. The interactive component may be a touch screen that can be used to set working modes, view load power usage, monitor device status, and configure parameters.

[0105] With this design, power users can view electricity usage, peak and off-peak periods and other information in real time through interactive components, so as to adjust their electricity usage habits and reduce the use of high-power electrical appliances during peak periods, which leads to increased electricity costs.

[0106] In an exemplary embodiment, a power supply system is provided, comprising an energy storage device group and an on-grid / off-grid switching system as described in any of the above embodiments. The energy storage device group is connected to a load via the on-grid / off-grid switching system, and the load is also connected to a public power grid via the on-grid / off-grid switching system. Specifically, the on-grid / off-grid switching system can switch the operating mode to on-grid mode, where the load is powered by the power grid or the energy storage device group, and to off-grid mode, where the load is powered by the energy storage device group.

[0107] The specific limitations in the embodiment of the power supply system can be found in the above limitations on the on-grid and off-grid switching system, which will not be repeated here.

[0108] In a specific embodiment, Figure 3 As shown, a power supply system is provided. Energy storage devices 1 to N (energy storage device group) are connected in parallel and then connected to static transfer switch input terminal 1, circuit breaker 3, circuit breaker 2, and a contactor. Circuit breaker 3 is connected to load 3, which is connected in parallel to load meter 3. Circuit breaker 2 is connected to load 2, which is connected in parallel to load meter 2. A contactor connects circuit breaker 1 to static transfer switch input terminal 1, which is connected to the grid, which is connected in parallel to grid-connected meter 1. Static transfer switch input terminal 2 is connected to circuit breaker 1, and the static transfer switch output is connected to critical loads, which are connected in parallel to load meter 1, a controller, and a switch. Load 2 has a higher power supply priority than load 3, and critical loads have a higher power supply priority than load 2.

[0109] Please continue to refer to Figure 3 Energy storage devices 1 through N communicate and connect to the switch. The switch connects to the backend monitoring and controller. Load meter 1, grid-connected meter 1, load meter 2, and load meter 3 communicate and connect to the controller and backend monitoring. The power of the critical load, controller, and switch is fed back to the controller and backend monitoring via load meter 1. The amount of energy storage device power connected to the grid is fed back to the controller and backend monitoring via grid-connected meter 1. The power of loads 2 and 3 is fed back to the controller and backend monitoring via load meters 2 and 3.

[0110] These load meters monitor users' electricity usage in real time through built-in sensors, collecting parameters such as voltage, current, power, and power consumption. This data reflects changes in the corresponding load, helping users understand peak usage periods and load conditions. Based on user-set load limits, the meters can automatically limit device power usage or issue an alarm. When a user's load approaches or exceeds the set threshold, the meter sends an alarm to the controller and backend monitoring system, prompting them to reduce power usage. The controller then determines whether to cut off power to non-critical loads to prevent insufficient remaining power in the energy storage device and over-discharge of the battery. The meter assists the controller in adjusting power supply strategies. The controller monitors user power usage and adjusts the power supply strategy based on the real-time demand of the grid load. For example, during off-grid operation, if both Load 2 and Load 3 are operating simultaneously and the load is too high, the controller can remotely control the operation of Circuit Breaker 2 or Circuit Breaker 3 to reduce load power usage.

[0111] The touchscreen allows users to set load priorities based on their importance. When the remaining charge of the energy storage device approaches the limit, the controller can shut down low-priority loads according to the set load priority, preserving power supply to high-priority critical equipment. This management method improves the flexibility and reliability of power use.

[0112] At the same time, electricity usage data collected by the meter can be fed back to users via backend monitoring and the touchscreen. Users can view information such as electricity usage and peak load periods in real time, allowing them to adjust their electricity usage habits and reduce the use of high-power equipment during peak periods. The system also provides users with personalized energy-saving recommendations to help optimize load management. By collecting electricity usage data from key loads, load 2 and load 3 controllers, and switches, the controller can use the meter system to predict future electricity demand trends and implement load control. This helps plan power generation and transmission and distribution resources in advance, optimize grid operating efficiency, and avoid power shortages during peak periods.

[0113] like Figure 4 Figure 2 shows the controller's communication architecture. The controller primarily uses three types of ports to facilitate communication, control, and feedback for the entire on-grid and off-grid system. The communication ports enable networking with the switch, backend monitoring, grid-connected meters 1-3, and the touch screen. The DO ports connect to the contactor coils and circuit breakers 1-3 for electrical control, enabling on / off control of the contactors and circuit breakers. The DI ports connect to the contactor auxiliary contacts and circuit breaker auxiliary contacts for monitoring the on / off status of the contactors and circuit breakers.

[0114] The static transfer switch is a switching device that selects one of two power sources. If the primary power source fails, the static transfer switch automatically switches to the secondary power source to supply the load. If the secondary power source also fails, the static transfer switch reverts to the primary power source. This ensures uninterrupted power supply to critical loads, controllers, and switches during on-grid and off-grid switching.

[0115] For example, the circuit breaker provided in the present application integrates leakage protection, electric operation, and auxiliary contacts. When leakage occurs in the load corresponding to the circuit breaker, it is automatically disconnected to achieve leakage protection. The electric operation can achieve unmanned control when the corresponding circuit breaker needs to be opened and closed. The action of the electric operation is controlled by the DO port of the controller to control the opening and closing of the circuit breaker. The auxiliary contacts of the circuit breaker are a group of passive dry nodes that can be opened and closed when the circuit breaker is opened and closed, and the current circuit breaker status is fed back through the DI port of the controller.

[0116] like Figure 5 As shown, a method for switching between grid-connected and off-grid power supply systems is provided. The method specifically includes the following steps:

[0117] First, after power-on, initialization is completed, touch screen operating parameters are set, and the system is started up and switched on and off, the system will operate according to the set working mode;

[0118] When entering the set working mode, or when switching the working mode later, the controller must first determine whether the working mode should be off-grid mode or grid-connected mode;

[0119] When entering the grid-connected mode, first determine whether circuit breaker 1 is closed. If not, the contactor will not operate and continue to wait. After circuit breaker 1 is closed, the contactor will be attracted to close circuit breakers 2 / 3, and power will be supplied to each load through the energy storage device group or the grid;

[0120] When entering off-grid mode, first determine whether the contactor is closed;

[0121] When the contactor is in the energized state, it indicates that the working mode is in the grid-connected mode before the switching action, and then determines whether it is an active grid-connected or grid-disconnected mode;

[0122] If the system is actively connected to the grid and disconnected from the grid, close 2 / 3 of the circuit breakers, supply power to the loads through the energy storage device group, and then open the contactor to disconnect the grid;

[0123] If the grid is disconnected passively, the contactor is directly disconnected and 2 / 3 of the circuit breaker is kept closed, and power is supplied to each load through the energy storage device group;

[0124] When the contactor is in the disconnected state, it indicates that the set off-grid mode is entered for the first time. Circuit breakers 2 / 3 are directly closed and power is supplied to each load through the energy storage device group.

[0125] During the power supply process, if the control instruction is received again to indicate that the working mode needs to be switched, the controller will continue to return to the step of determining whether the working mode needs to be entered into the off-grid mode or the grid-connected mode;

[0126] Similarly, during the power supply process, when there is an energy storage device with a remaining power of ≤20% in the energy storage device group, the energy storage device group switches from off-grid mode to grid-connected mode for power replenishment. When there is no energy storage device with a remaining power of ≤20% in the energy storage device group, each load meter confirms the load power consumption, and the energy storage device group continues to supply power according to the current remaining power level.

[0127] like Figure 6 As shown, a power supply method using an energy storage device group is provided, which specifically includes the following processes:

[0128] Each load meter confirms the load's power usage, and the energy storage device group estimates the remaining power. Assuming the energy storage device group has four remaining power levels, when the remaining power level is in level 1, the energy storage device group generates power to all loads based on the power usage detected by each load meter. In grid-connected mode, the energy storage device group can also transmit its remaining power to the grid. When grid-connected meter 1 detects reverse flow, the energy storage device group's grid-connected power is reduced. When the remaining power level is in level 2, the energy storage device group generates power to all loads based on the power usage detected by each load meter, without transmitting power to the grid. When the remaining power level is in level 3, circuit breaker 3 is opened, and the energy storage device group generates power to the core load and load 2 based on the power usage detected by load meters 2 and 1. When the remaining power level is in level 4, circuit breakers 2 / 3 are opened, and the energy storage device group generates power to the core load based on the power usage detected by load meter 1.

[0129] In this embodiment, in the scenario of active on-grid and off-grid switching, an AC contactor is used for on-grid and off-grid switching, which greatly reduces costs. In the application scenario to solve the problem of inconsistent load types, the core load is confirmed, and the core load is switched with a static transfer switch, and other off-grid loads are switched with a contactor. The static transfer switch for the core load has a small current and low cost. Different loads are controlled by different circuit breakers. The circuit breaker integrates leakage protection, electric operation, and auxiliary contacts. It can remotely control the start and stop, realize automatic leakage protection and start and stop status feedback. It can provide real-time feedback on the current load power consumption and control the start and stop of each load in a planned manner according to the remaining power of the energy storage system group.

[0130] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0131] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A grid-connected and off-grid switching system, characterized in that: It includes a controller, and a static transfer switch, a grid-connected contactor, a grid circuit breaker, and a load power supply switch assembly connected to the controller; The first power-taking end of the static transfer switch is connected to the grid through the grid circuit breaker, the second power-taking end of the static transfer switch is connected to the energy storage device group, and the power-supply end of the static transfer switch is connected to the first load and the controller; The power-taking end of the load power supply switch assembly is connected to the power grid through the grid-connected contactor and the grid circuit breaker in sequence, the power-taking end is connected to the energy storage device group, the power-supply end of the load power supply switch assembly is connected to a second load, and the energy storage device group is connected to the power grid through the grid-connected contactor and the grid circuit breaker in sequence, and the power supply priority of the first load is higher than that of the second load; The controller is used to control the operation of the static transfer switch, the grid-connected contactor and the load power supply switch assembly, so as to switch the working mode to the grid-connected mode and supply power through the power grid or the energy storage device group, and to switch the working mode to the off-grid mode and supply power through the energy storage device group.

2. The on-grid and off-grid switching system according to claim 1, characterized in that: When the operating mode needs to be switched to the off-grid mode, the controller determines a target switching mode according to the first on / off state of the grid-connected contactor and the power supply state of the grid, thereby switching the operating mode to the off-grid mode.

3. The on-grid and off-grid switching system according to claim 2, characterized in that: The controller determines that the target switching mode is active grid connection and disconnection when the first switching state is a closed state and the power supply state of the grid is a normal state; The controller determines that the target switching mode is passive grid connection and disconnection when the first switching state is a closed state and the power supply state of the power grid is an abnormal state; When the first switching state is the open state, the controller determines that the target switching mode is to directly disconnect from the grid.

4. The on-grid and off-grid switching system according to claim 3, characterized in that: When the target switching mode is active grid connection and disconnection, the controller operates and controls the target power supply end of the static transfer switch to the second power supply end, supplies power through the energy storage device group, and then controls the grid-connected contactor to be in an off state; When the target switching mode is passive grid connection and disconnection, the controller controls the grid contactor to be in an off state, and controls the load power supply switch assembly to operate, so as to supply power through the energy storage device group; When the target switching mode is direct disconnection from the grid, the controller controls the load power supply switch component to operate and supply power through the energy storage device group.

5. The on-grid and off-grid switching system according to claim 1, characterized in that: When the operating mode needs to be switched to the grid-connected mode and the second opening and closing state of the grid circuit breaker is the closed state, the controller controls the grid-connected contactor and the load power supply switch assembly to be in the closed state, thereby switching the operating mode to the grid-connected mode.

6. The on-grid and off-grid switching system according to claim 1, characterized in that: When the working mode is the grid-connected mode and is in a preset peak time period, the controller controls the target power-taking end of the static transfer switch to be the second power-taking end, the grid-connected contactor and the load power supply switch assembly to be in a closed state, and power is supplied through the energy storage device group; When the working mode is the grid-connected mode and is in a preset valley time period, the controller controls the target power supply end of the static transfer switch to be the first power supply end, the grid-connected contactor and the load power supply switch assembly to be in a closed state, and power is supplied through the power grid.

7. The on-grid and off-grid switching system according to any one of claims 1 to 6, characterized in that: It also includes a switch, the switch is connected to the power supply end of the static transfer switch, the energy storage device group communicates with the controller through the switch, and is used to feedback the remaining power status of the energy storage device group; The second load includes multiple types of sub-loads with descending power supply priorities, the load power supply switch assembly includes load power supply switches matching the number of the sub-loads, and each of the sub-loads obtains power through a corresponding load power supply switch; The controller is used to determine the target power supply priority according to the power supply gear to which the remaining power status belongs, and control the opening and closing state of the corresponding load power supply switch based on the target power supply priority to realize power supply through the energy storage device group.

8. The on-grid and off-grid switching system according to claim 7, characterized in that: Also included is a power consumption monitoring module connected to the controller; The power consumption monitoring module is configured to monitor and obtain the first power consumption corresponding to the controller, the switch, and the first load, and to monitor and obtain the sub-power consumption corresponding to each of the sub-loads; The controller is used to control the output power value of the energy storage device group according to the first power consumption and each of the sub-power consumptions.

9. The on-grid and off-grid switching system according to claim 7, characterized in that: The controller controls the energy storage device group to discharge to the power grid when the working mode is the grid-connected mode and the power supply level to which the remaining power level of the energy storage device group belongs is the highest power supply level.

10. The on-grid and off-grid switching system according to claim 7, characterized in that: When the energy storage device group includes a low-power energy storage device whose remaining power state is lower than a preset power threshold, the controller switches the working mode to the grid-connected mode and controls the charging of the low-power energy storage device through the power grid.

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