Power supply system containing network construction type energy storage and power supply operation method

Abstract

The invention discloses a power supply system containing network construction type energy storage and a power supply operation method, which can realize stable power supply of important loads. The system comprises a multi-path power grid power supply unit, an interconnection switch, at least one network construction type energy storage unit, an automatic change-over switch and an uninterruptible power supply. The operation method is divided into four scenes: multi-path power grid split operation and energy storage grid connection in a normal state; if a single-path power grid breaks down, corresponding energy storage off-grid voltage stabilization is carried out, then the interconnection switch is closed and is loaded by an adjacent power grid, and energy storage complex grid connection is carried out; when the whole power grid fails, all energy storage off-grid parallel power supply is realized; when full energy storage fails, the uninterruptible power supply supplies power through the automatic change-over switch. The grid-forming type energy storage unit is rapid in off-grid switching, instantaneous voltage stabilization is achieved when a single path breaks down, a diesel generator is not needed, and voltage drop and pollution are avoided. The independent bus blocks fluctuation conduction, energy storage continuous voltage stabilization is matched with interconnection switch time sequence control, and switching impact is eliminated. A three-level guarantee of a power grid, energy storage and an uninterruptible power supply is constructed, the risk of full power loss is handled, and the problem of important load power loss is thoroughly avoided.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and more specifically, to a power supply system and power supply operation method incorporating grid-type energy storage. Background Technology

[0002] In critical load power supply scenarios such as hospitals, data centers, and key industrial production lines, a power outage or voltage anomaly can lead to serious consequences such as medical accidents, data loss, and production interruptions. Therefore, ensuring continuous and stable power supply to critical loads is of paramount importance, and a collaborative power supply guarantee system needs to be built.

[0003] Currently, traditional power supply solutions suffer from two core problems: First, while diesel generators as backup power can cope with power outages, they suffer from low operating load rates, low power generation efficiency, high fuel consumption, high maintenance costs, and significant environmental pollution. Furthermore, they are slow to respond and prone to short-term voltage drops. Second, even when multiple power grids are used, they are often simple parallel or direct switching designs. Fluctuations in one grid circuit can easily propagate to other circuits, leading to overall voltage instability. The lack of intermediate buffering mechanisms makes them susceptible to current surges during grid switching, causing sudden rises and falls in bus voltage, which fails to meet the stringent power stability requirements of precision equipment. For example, voltage fluctuations in industrial high-frequency processing equipment can lead to deviations in processing accuracy; data center server power modules are prone to triggering protective shutdowns during sudden voltage changes. These problems highlight the inherent deficiencies of traditional solutions in power stability, making them unable to meet the high power quality requirements of critical loads.

[0004] Based on this, this application proposes a power supply system and power supply operation method to overcome the shortcomings of the prior art, achieve stable power supply to important loads, and avoid the risk of power outages. Summary of the Invention

[0005] This application provides a power supply system and operation method incorporating grid-type energy storage. Through millisecond-level switching of grid-type energy storage, independent bus design and timing control of interconnection switches, as well as three-level power supply protection of the power grid, energy storage and uninterruptible power supply, it avoids voltage drops, fluctuation transmission and switching impacts, and completely avoids the risk of power failure of important loads, thus achieving a dual improvement in power supply continuity and stability.

[0006] A power supply system incorporating grid-type energy storage includes:

[0007] Multiple power grid supply units from different sources, each power grid supply unit is connected to an independent switch station bus through an incoming line switch;

[0008] Multiple switchyard buses, adjacent switchyard buses are connected by tie switches;

[0009] At least one grid-type energy storage unit, each of the grid-type energy storage units being connected to at least one section of the switch station bus via an energy storage switch, the grid-type energy storage unit being configured to switch between grid-connected mode and off-grid mode, and providing voltage and frequency support to the connected switch station bus in off-grid mode;

[0010] Automatic transfer switches, with their input terminals connected to at least two different sections of the switch station bus in the bus network;

[0011] An uninterruptible power supply (UPS) has its input terminal connected to the output terminal of the automatic transfer switch, and its output terminal connected to the load.

[0012] Optionally, the multi-source power grid supply unit includes three power grid supply units, which are respectively connected to the first switch station bus, the second switch station bus, and the third switch station bus;

[0013] The grid-type energy storage unit includes a first grid-type energy storage unit and a second grid-type energy storage unit. The first grid-type energy storage unit is connected to the first switch station bus, and the second grid-type energy storage unit is connected to the third switch station bus.

[0014] The tie switch includes a first tie switch and a second tie switch. The first tie switch is connected between the first switch station bus and the second switch station bus, and the second tie switch is connected between the second switch station bus and the third switch station bus.

[0015] Optionally, the connecting switch is a circuit breaker with a synchronization detection and closing function.

[0016] Optionally, when the grid-connected energy storage unit detects that the incoming switch of the connected switch station bus has tripped, it switches from grid-connected mode to off-grid mode and provides independent voltage and frequency support for the connected switch station bus.

[0017] Optionally, the automatic transfer switch monitors the voltage status of each connected switch station bus in real time, and automatically switches to another normal switch station bus when it detects that the currently powered switch station bus is undervoltage.

[0018] Optionally, the uninterruptible power supply may switch to battery mode to continuously supply power to the load during the automatic transfer switch switching process or when all switch station buses lose voltage.

[0019] A power supply operation method, applied to the aforementioned power supply system containing grid-type energy storage, includes:

[0020] During normal system operation, multiple power grid supply units operate separately with their respective corresponding switch station buses, and the grid-type energy storage unit operates in grid-connected mode.

[0021] When a fault in a power grid unit causes the incoming switch to trip, the fault section grid-type energy storage unit connected to the busbar of the fault section switch station corresponding to the tripped incoming switch switches switches to off-grid mode to support the busbar voltage of the fault section switch station.

[0022] After the system stabilizes, the interconnection switch connecting the busbar of the faulty section switch station and the busbar of the normal section switch station is closed. The normal grid power supply unit adjacent to the faulty grid power supply unit drives the busbar of the faulty section switch station, and the grid-type energy storage unit of the faulty section resumes grid connection mode.

[0023] When all grid power supply units fail, all grid-type energy storage units switch to off-grid mode and operate in parallel to supply power to all switch station buses.

[0024] When all grid-type energy storage units fail and go out of service, the load is powered by an uninterruptible power supply through an automatic transfer switch.

[0025] Optionally, before closing the tie switch connecting the faulty section switch station bus and the normal section switch station bus, a synchronization check is performed to ensure that the voltage, frequency, and phase of the faulty section switch station bus and the normal section switch station bus are consistent.

[0026] Optionally, the automatic transfer switch monitors the voltage of each section of the switch station bus at the input terminal in real time. When it detects that the current power supply switch station bus is undervoltage, it switches the load to be powered by another normal switch station bus. During the switching process, the uninterruptible power supply maintains continuous power supply to the load.

[0027] Optionally, when all grid-connected energy storage units are operating off-grid in parallel, a master-slave control or droop control strategy is adopted to stabilize the voltage and frequency of all switchyard buses.

[0028] As can be seen from the above technical solutions, the power supply system and power supply operation method provided in this application embodiment include a grid-type energy storage power supply system comprising multiple power grid supply units from different sources, a tie switch between adjacent substation buses, at least one grid-type energy storage unit, an automatic transfer switch with its input end connected to at least two bus sections, and an uninterruptible power supply (UPS) with its input end connected to the automatic transfer switch and its output end connected to the load. Its operation method is as follows: when the system is normal, multiple power grids operate in split mode, and the grid-type energy storage is connected to the grid; when a single power grid fails and trips, the energy storage corresponding to the faulty bus switches to off-grid mode to support the voltage, and after stabilization, the tie switch is closed to allow the adjacent normal power grid to carry the load, and the energy storage is restored to grid connection; when the entire power grid fails, all energy storage units are off-grid and supplied in parallel; when all energy storage units fail, the UPS supplies power through the automatic transfer switch.

[0029] This application avoids the shortcomings of traditional methods and achieves stable power supply to critical loads. First, the grid-connected energy storage unit has millisecond-level on-grid and off-grid switching capability. In the event of a single grid failure, it can instantly switch to off-grid mode to support the bus voltage without relying on diesel generators, thus avoiding short-term voltage drops and eliminating pollutant emissions. Second, addressing the issues of fluctuation transmission and switching impact caused by simple parallel connection of multiple grids, the independent bus design in the system blocks the transmission path of fluctuations from a single grid. The energy storage unit continuously provides voltage support during switching, and with the timing control of the tie switch, the current surge during grid switching is completely eliminated, effectively controlling bus voltage fluctuations and meeting the stringent requirements of precision equipment for power supply stability. Third, addressing the inability of traditional solutions to cope with the risk of total power outages, the system constructs a three-level power supply guarantee system consisting of the grid, energy storage, and uninterruptible power supply. In the event of a grid-wide failure, multiple grid-connected energy storage units can operate in parallel, maintaining stable voltage and frequency through coordinated control to supply power to all busbars. Even if all energy storage units fail, automatic transfer switches can quickly switch to uninterruptible power supply, forming redundant protection, completely avoiding the risk of power loss for critical loads, and achieving a dual improvement in power supply continuity and stability. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of a power supply system with grid-type energy storage disclosed in an embodiment of this application;

[0032] Figure 2 This is a flowchart of a power supply operation method disclosed in an embodiment of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] The following section introduces the solution proposed in this application. The technical solution is as follows, and details are provided below.

[0035] This application discloses a power supply system incorporating grid-type energy storage, comprising:

[0036] Multiple power grid supply units from different sources, each power grid supply unit is connected to an independent switch station bus through an incoming line switch;

[0037] Multiple switchyard buses, adjacent switchyard buses are connected by tie switches;

[0038] At least one grid-type energy storage unit, each of the grid-type energy storage units being connected to at least one section of the switch station bus via an energy storage switch, the grid-type energy storage unit being configured to switch between grid-connected mode and off-grid mode, and providing voltage and frequency support to the connected switch station bus in off-grid mode;

[0039] Automatic transfer switches, with their input terminals connected to at least two different sections of the switch station bus in the bus network;

[0040] An uninterruptible power supply (UPS) has its input terminal connected to the output terminal of the automatic transfer switch, and its output terminal connected to the load.

[0041] Specifically, multiple power grid supply units provide initial power input to the system. Each power grid supply unit is connected to the switch station bus through a unique incoming switch, and each power grid supply unit corresponds to only one section of the switch station bus, thus forming a multi-section independent switch station bus structure. This independent bus design can effectively prevent the operation fluctuations of a single power grid from being transmitted to other buses, laying the foundation for stable system operation.

[0042] A tie switch is installed between each of the two adjacent bus sections. The tie switch is normally in the open state to maintain the independent operation of each bus. When a fault occurs in the power grid supply unit connected to a certain bus section, the tie switch can be closed under the preset control logic to realize the power connection between the faulty bus and the adjacent normal bus, so that the normal power grid supply unit can provide power support for the load on the faulty bus side.

[0043] As a key energy storage and voltage stabilization component of the system, the grid-type energy storage unit is connected to at least one section of the substation bus via a dedicated energy storage switch. Its core configuration lies in its bidirectional switching capability between grid-connected and off-grid modes. During normal system operation, the grid-type energy storage unit is in grid-connected mode, working in conjunction with the grid power supply unit to supply power to the bus. When the grid power supply unit connected to the bus trips due to a fault, and the bus loses grid power input, the grid-type energy storage unit can quickly switch to off-grid mode, providing immediate voltage and frequency support to the bus, preventing voltage drops or frequency instability, and ensuring the transient power supply needs of sensitive loads on the bus side.

[0044] The automatic transfer switch (ATS) employs a multi-bus connection design at its input, specifically connecting to at least two different switchyard buses in the bus network. Its function is to monitor the power supply status of the connected buses in real time. When a power supply anomaly occurs on one of the connected buses, the ATS can quickly switch to other normally supplying buses, ensuring the continuity of power at its output. The uninterruptible power supply (UPS) is directly connected to the output of the ATS, and its output is connected to the system load, serving as the ultimate power supply redundancy guarantee for the system. When all buses connected to the ATS are unable to provide normal power, the UPS can immediately start and supply power to the load, completely avoiding the risk of operational interruption due to power loss of critical loads and achieving multi-level protection of the system's power supply.

[0045] The connecting switch is a circuit breaker with a synchronization detection and closing function.

[0046] When the grid-type energy storage unit detects that the incoming switch of the connected switch station bus has tripped, it switches from grid-connected mode to off-grid mode and provides independent voltage and frequency support for the connected switch station bus.

[0047] Specifically, the tie switch adopts a circuit breaker structure with synchronization detection and closing function. This function is key to ensuring safe grid connection between buses and avoiding closing impact. During normal system operation, the tie switch remains open to maintain the independent operation of each switch station bus. When a section of a switch station bus loses power due to a fault in the corresponding power supply unit, and the bus has switched from grid-connected energy storage unit to off-grid mode and achieved voltage and frequency stability, the tie switch will initiate the synchronization detection and closing process. It first performs real-time detection of three key parameters: voltage amplitude, frequency, and phase difference between the faulty bus (supported by energy storage) and the adjacent normal bus. Only when the above parameters of both buses meet the preset synchronization closing conditions (i.e., the parameter difference is within the safe threshold range) will the tie switch perform the closing action. This synchronization control logic can completely eliminate the closing current surge caused by parameter inconsistencies between buses, preventing damage to bus-side equipment, grid-type energy storage units, and grid power supply units from the surge current. At the same time, it ensures that the two buses can smoothly exchange power after closing, guaranteeing a smooth transition of the system from a fault state to a recovery state.

[0048] Regarding the switching control and support functions of the grid-connected energy storage unit, it possesses a status linkage detection mechanism with the incoming line switch of the connected substation bus. The grid-connected energy storage unit acquires the opening and closing status signals of the incoming line switch in real time through a signal acquisition module, or monitors whether there is grid-side power input to the bus through voltage and current detection modules. When an incoming line switch trips (i.e., the bus is disconnected from the grid power supply unit), or when the bus loses grid power input and a voltage drop trend is detected, the grid-connected energy storage unit triggers a preset mode switching command, completing the switch from grid-connected mode to off-grid mode in a very short time. After switching to off-grid mode, the grid-connected energy storage unit no longer relies on the grid signal. Instead, it uses its own independent control module to autonomously adjust and stably output the voltage amplitude and frequency of the connected bus, providing independent voltage and frequency support for the bus. This ensures that during the transient process after a grid fault, the bus voltage and frequency remain within the operating range that the load can withstand, avoiding load outages due to short-term voltage loss or parameter fluctuations, and allowing sufficient time for the subsequent closing of the tie switch and the restoration of grid power supply.

[0049] This application provides an optional implementation scheme. This optional implementation scheme further refines the system structure by specifying the corresponding configuration of three power grids, three bus sections, two energy storage sections, and two tie switches, thereby ensuring the feasibility of the technical solution. The specific connection relationships and functional adaptations are as follows:

[0050] The multi-source power grid supply unit includes three power grid supply units, which are respectively connected to the first switch station bus, the second switch station bus, and the third switch station bus;

[0051] The grid-type energy storage unit includes a first grid-type energy storage unit and a second grid-type energy storage unit. The first grid-type energy storage unit is connected to the first switch station bus, and the second grid-type energy storage unit is connected to the third switch station bus.

[0052] The tie switch includes a first tie switch and a second tie switch. The first tie switch is connected between the first switch station bus and the second switch station bus, and the second tie switch is connected between the second switch station bus and the third switch station bus.

[0053] Specifically, the multi-source power grid supply unit consists of three independent power grids. Each of the three power grid supply units is connected one-to-one to the busbars of the first, second, and third switch stations via its own dedicated incoming switch, forming an independent power supply link. Under this configuration, the three switch station busbars operate independently without interference under normal conditions. Each busbar is only affected by the power input of its corresponding power grid supply unit, effectively isolating voltage fluctuations and frequency deviations from a single power grid. This prevents anomalies in one power grid from interfering with the power supply stability of the other two busbars, making it particularly suitable for multi-load scenarios with high power supply accuracy requirements.

[0054] The configuration of the tie switches is precisely matched with the busbar layout. The two ends of the first tie switch are directly connected to the first and second switchbar busbars, respectively, while the two ends of the second tie switch are directly connected to the second and third switchbar busbars, respectively. Under normal circumstances, both the first and second tie switches are in the open state, maintaining the independent operation of the three busbars. When the power supply unit corresponding to any busbar fails, the power supply to the faulty busbar can be connected to the nearest normal busbar by closing the adjacent tie switches. For example, when the first busbar grid fails, the first tie switch can be closed to supply power from the second busbar; when the third busbar grid fails, the second tie switch can be closed to supply power from the second busbar; when the second busbar grid fails, the first and second tie switches, or both, can be closed according to actual needs, with the first and third busbars coordinating to supply power, improving the flexibility of fault response.

[0055] The configuration of the grid-type energy storage units provides precise support for critical buses. The first grid-type energy storage unit is connected to the first switchyard bus via a dedicated energy storage switch, and the second grid-type energy storage unit is connected to the third switchyard bus via a dedicated energy storage switch. With this configuration, the two energy storage units can provide independent grid-connected and off-grid support for their respective connected buses: when the grid power supply unit of the first bus fails or the incoming switch trips, the first grid-type energy storage unit can quickly switch to off-grid mode to provide voltage and frequency support for the first bus; when the grid power supply unit of the third bus fails or the incoming switch trips, the second grid-type energy storage unit can simultaneously switch to off-grid mode to provide voltage and frequency support for the third bus. While the second bus is not directly connected to the grid-type energy storage units, it can obtain energy storage support from the first and third buses through the first and second tie switches respectively (if the corresponding bus energy storage is in off-grid mode), or obtain grid support when the adjacent bus grid is normal, achieving full coverage of energy storage protection for all three bus segments.

[0056] Furthermore, the automatic transfer switch in this implementation scheme can be selected to connect to any two of the three busbars according to the load distribution requirements, so as to monitor the power supply status of different busbars and realize switching; the uninterruptible power supply is still connected to the output terminal of the automatic transfer switch, and provides ultimate power guarantee for important loads when none of the three busbars can provide normal power supply, ensuring that this optional implementation scheme also has complete power supply redundancy capability.

[0057] by Figure 1 For example, let's explain in detail:

[0058] Figure 1 The three power grid supply units are connected to the busbars of three switching stations respectively. The #1 and #2 grid-type energy storage units use grid-type control and are connected to the #1 and #3 switching station busbars respectively. Loads are connected to the #1 and #3 switching station busbars via uninterruptible power supplies and automatic transfer switches.

[0059] Under normal operating conditions, each of the three power grid supply units operates with a section of busbar. The #1 grid-type energy storage unit and the #2 grid-type energy storage unit are connected to the #1 switch station busbar and the #3 switch station busbar respectively and operate in grid-connected mode. Switches S1-1, S1-2, S1-3, S1-4, S2-1, S3-1, S3-2, S3-3, and S3-4 are closed, while switches S2-2 and S2-3 are open.

[0060] If a fault occurs in the #1 power supply unit, the S1-1 switch will trip. Upon detecting the S1-1 trip, the #1 grid-type energy storage unit will switch from grid-connected mode to off-grid mode, operating off-grid with the #1 substation bus. After stabilization, the S2-2 switch will be closed via synchronization, allowing the #2 power supply unit to operate with both the #1 and #2 substation buses. The #1 grid-type energy storage unit will then switch from off-grid mode to grid-connected mode.

[0061] If a fault occurs in the #2 power grid supply unit, the S2-1 switch will trip. Upon detecting the S2-1 trip, the #1 grid-type energy storage unit will switch from grid-connected mode to off-grid mode, operating off-grid with the #1 and #2 switch station buses. After stabilization, the S2-3 switch will be closed via synchronization detection, allowing the #3 power grid supply unit to operate with the #1, #2, and #3 switch station buses. The #1 grid-type energy storage unit will then switch from off-grid mode to grid-connected mode.

[0062] If the #3 power supply unit fails and the S3-1 switch trips, the #1 grid-connected energy storage unit and the #2 grid-connected energy storage unit will switch from grid-connected mode to off-grid mode and operate in parallel, with the #1 switch station bus, the #2 switch station bus, and the #3 switch station bus in off-grid operation.

[0063] If the #1 grid-type energy storage unit subsequently fails to operate, it will operate independently with the #1 switch station bus, the #2 switch station bus, and the #3 switch station bus.

[0064] Subsequently, the #2 grid-type energy storage unit went out of operation due to a fault, and the #1 switch station bus, #2 switch station bus, and #3 switch station bus all lost power, with the load being powered by an uninterruptible power supply.

[0065] Under normal operation, the automatic transfer switch is powered by the #1 switch station bus. If a fault occurs and the #1 switch station bus loses power, the automatic transfer switch will activate, switching power to the #3 switch station bus. During the automatic transfer switch switching, the uninterruptible power supply (UPS) will switch to battery mode to supply power to the load. After the automatic transfer switch switching is complete, the UPS will switch back from battery mode to main power supply mode, and the load will be powered by the #3 switch station bus.

[0066] As can be seen from the above technical solutions, the power supply system with grid-type energy storage provided in this application includes multiple power grid supply units from different sources, a tie switch between adjacent substation buses, at least one grid-type energy storage unit, an automatic transfer switch with its input end connected to at least two bus sections, and an uninterruptible power supply (UPS) with its input end connected to the automatic transfer switch and its output end connected to the load. Its operation method is as follows: When the system is normal, multiple power grids operate in split mode, and the grid-type energy storage is connected to the grid; when a single power grid fails and trips, the energy storage corresponding to the faulty bus switches to off-grid mode to support the voltage, and after stabilization, the tie switch is closed to allow the adjacent normal power grid to carry the load, and the energy storage is restored to grid connection; when the entire power grid fails, all energy storage units are off-grid and connected in parallel; when all energy storage units fail, the UPS supplies power through the automatic transfer switch.

[0067] This application avoids the shortcomings of traditional methods and achieves stable power supply to critical loads. First, the grid-connected energy storage unit has millisecond-level on-grid and off-grid switching capability. In the event of a single grid failure, it can instantly switch to off-grid mode to support the bus voltage without relying on diesel generators, thus avoiding short-term voltage drops and eliminating pollutant emissions. Second, addressing the issues of fluctuation transmission and switching impact caused by simple parallel connection of multiple grids, the independent bus design in the system blocks the transmission path of fluctuations from a single grid. The energy storage unit continuously provides voltage support during switching, and with the timing control of the tie switch, the current surge during grid switching is completely eliminated, effectively controlling bus voltage fluctuations and meeting the stringent requirements of precision equipment for power supply stability. Third, addressing the inability of traditional solutions to cope with the risk of total power outages, the system constructs a three-level power supply guarantee system consisting of the grid, energy storage, and uninterruptible power supply. In the event of a grid-wide failure, multiple grid-connected energy storage units can operate in parallel, maintaining stable voltage and frequency through coordinated control to supply power to all busbars. Even if all energy storage units fail, automatic transfer switches can quickly switch to uninterruptible power supply, forming redundant protection, completely avoiding the risk of power loss for critical loads, and achieving a dual improvement in power supply continuity and stability.

[0068] Figure 2 This is a flowchart illustrating a power supply operation method disclosed in an embodiment of this application. This power supply operation method is applied to the aforementioned power supply system containing grid-type energy storage.

[0069] like Figure 2 As shown, the method may include:

[0070] Step D1: When the system is running normally, the multiple power grid supply units operate separately with their respective corresponding switch station buses, and the grid-type energy storage unit operates in grid-connected mode.

[0071] Specifically, when the system is in normal operation, its core operating logic is a combination of independent grid load-bearing and grid-connected energy storage. At this time, the incoming switches of multiple grid power supply units are all closed. Each grid power supply unit only provides power to its corresponding connected substation bus, and the interconnecting switches between adjacent substation buses remain open, thus achieving split operation of multiple grids. This operating mode can completely prevent abnormal signals such as voltage fluctuations and frequency deviations from a single grid from being transmitted to other buses, ensuring that the loads on each bus receive stable grid power input. Simultaneously, each grid-type energy storage unit connects to its corresponding bus through its dedicated energy storage switch and operates in grid-connected mode: on the one hand, the energy storage unit can work with the grid power supply unit to supply power to the bus, participating in system frequency regulation and peak shaving, and smoothing grid load fluctuations; on the other hand, the energy storage unit is in hot standby mode, monitoring bus voltage, frequency, and the status of the corresponding grid incoming switch in real time, preparing for rapid switching in subsequent fault scenarios.

[0072] Step D2: When a fault in a power supply unit of a certain power grid causes the incoming switch to trip, the fault section grid-type energy storage unit connected to the busbar of the fault section switch station corresponding to the tripped incoming switch switches switches to off-grid mode to support the busbar voltage of the fault section switch station.

[0073] Specifically, when a power supply unit of a power grid triggers its protection mechanism due to a short circuit, undervoltage, or other fault, causing its corresponding incoming switch to trip, the incoming switch will simultaneously send a trip signal to the associated grid-connected energy storage unit. Alternatively, the energy storage unit may use its own voltage / current detection module to monitor in real time whether the busbar of the corresponding faulty section has lost power input from the grid and whether the voltage is showing a downward trend. At this time, the grid-connected energy storage unit of the faulty section will initiate a millisecond-level rapid switching procedure, switching from grid-connected mode to off-grid mode in a very short time. After the switching is completed, the energy storage unit will autonomously adjust the amplitude and frequency of its output voltage based on its own independent control strategy to stabilize it within the preset rated range, providing continuous voltage support to the busbar of the faulty section. This process can effectively avoid voltage drops or frequency instability caused by sudden power loss on the faulty busbar, ensuring that sensitive loads on the busbar side can still operate normally during the fault transient phase and preventing the load from triggering shutdown protection due to short-term power loss.

[0074] Step D3: After the system stabilizes, close the interconnection switch connecting the busbar of the faulty section switch station and the busbar of the normal section switch station. The normal grid power supply unit adjacent to the faulty grid power supply unit will drive the busbar of the faulty section switch station to operate, and the grid-type energy storage unit of the faulty section will resume grid connection mode.

[0075] Specifically, the system stability criterion is that, in off-grid mode, the grid-connected energy storage unit in the faulty section has stabilized the voltage amplitude and frequency of the busbar at the faulty section switchyard within the preset synchronous closing allowable range, and this stable state continues for a preset time without voltage fluctuations or frequency drift. At this point, the system control unit sends a closing command to the tie switch connecting the faulty section busbar and the adjacent normal section busbar. Before performing the closing action, the tie switch activates its built-in synchronization detection function, comparing the voltage amplitude, frequency, and phase difference between the faulty section busbar and the normal section busbar in real time. The tie switch closes only when the difference in all three parameters is less than a preset safety threshold. After the tie switch closes, the adjacent normal grid power supply unit supplies power to the faulty section busbar through the tie switch, gradually replacing the energy storage unit as the main power source for the faulty section busbar. Once the power supply to the faulty section busbar is fully supplied by the normal grid and the busbar voltage and frequency are consistent with the normal grid, the grid-connected energy storage unit in the faulty section switches back to grid-connected mode, restoring its coordinated operation with the grid, thus completing the single-circuit grid fault recovery process.

[0076] Step D4: When all grid power supply units fail, all grid-type energy storage units switch to off-grid mode and operate in parallel to supply power to all switch station buses.

[0077] Specifically, when all grid power supply units trigger incoming switch tripping due to grid-wide power outages or large-scale faults, resulting in all substation buses losing grid power input, the system will trigger the full-grid off-grid parallel control logic for energy storage. At this time, all grid-connected energy storage units capture the corresponding bus power outage signal through their own detection modules and simultaneously switch from grid-connected mode to off-grid mode. To achieve parallel operation of multiple energy storage units, each unit adopts a collaborative control strategy, such as master-slave control or droop control: one energy storage unit acts as the master unit, setting and maintaining the system's reference voltage and frequency; the remaining slave units track the voltage and frequency signals of the master unit in real time, automatically adjusting their own output power and phase to ensure that the output parameters of all energy storage units remain consistent, avoiding circulating current or uneven load distribution due to parameter deviations. Through this parallel operation mechanism, all grid-connected energy storage units can form a unified virtual grid, jointly supplying power to all substation buses within the system, ensuring the continuous power demand of all bus-side loads during grid-wide faults.

[0078] Step D5: When all grid-type energy storage units fail and exit, the uninterruptible power supply (UPS) will supply power to the load through an automatic transfer switch.

[0079] Specifically, when all grid-connected energy storage units shut down due to battery failure, control module malfunction, or other reasons, and are unable to provide voltage support to the switchyard bus, the system's power supply protection logic will switch to the uninterruptible power supply (UPS) redundancy mode. At this time, the automatic transfer switch (ATS) will monitor the power supply status of all switchyard buses connected to its input in real time. When it detects that all connected buses have no normal power output, the ATS will trigger a zero-delay switching action, quickly switching its input from the faulty bus to the connection with the UPS. Simultaneously, the UPS will immediately initiate the power supply procedure based on the ATS switching signal or its own power failure detection. If the UPS is online, it will always be in standby mode, capable of instantaneously outputting power to the load; if it is in backup mode, it will quickly start the inverter after detecting input power failure, ensuring uninterrupted power output. Ultimately, the UPS provides continuous power to the system load through the ATS until the grid or energy storage units return to normal operation, completely avoiding the risk of critical load power loss due to grid-wide or energy storage failures.

[0080] As can be seen from the above technical solutions, the power supply system and power supply operation method provided in this application embodiment include a grid-type energy storage power supply system comprising multiple power grid supply units from different sources, a tie switch between adjacent substation buses, at least one grid-type energy storage unit, an automatic transfer switch with its input end connected to at least two bus sections, and an uninterruptible power supply (UPS) with its input end connected to the automatic transfer switch and its output end connected to the load. Its operation method is as follows: when the system is normal, multiple power grids operate in split mode, and the grid-type energy storage is connected to the grid; when a single power grid fails and trips, the energy storage corresponding to the faulty bus switches to off-grid mode to support the voltage, and after stabilization, the tie switch is closed to allow the adjacent normal power grid to carry the load, and the energy storage is restored to grid connection; when the entire power grid fails, all energy storage units are off-grid and supplied in parallel; when all energy storage units fail, the UPS supplies power through the automatic transfer switch.

[0081] This application avoids the shortcomings of traditional methods and achieves stable power supply to critical loads. First, the grid-connected energy storage unit has millisecond-level on-grid and off-grid switching capability. In the event of a single grid failure, it can instantly switch to off-grid mode to support the bus voltage without relying on diesel generators, thus avoiding short-term voltage drops and eliminating pollutant emissions. Second, addressing the issues of fluctuation transmission and switching impact caused by simple parallel connection of multiple grids, the independent bus design in the system blocks the transmission path of fluctuations from a single grid. The energy storage unit continuously provides voltage support during switching, and with the timing control of the tie switch, the current surge during grid switching is completely eliminated, effectively controlling bus voltage fluctuations and meeting the stringent requirements of precision equipment for power supply stability. Third, addressing the inability of traditional solutions to cope with the risk of total power outages, the system constructs a three-level power supply guarantee system consisting of the grid, energy storage, and uninterruptible power supply. In the event of a grid-wide failure, multiple grid-connected energy storage units can operate in parallel, maintaining stable voltage and frequency through coordinated control to supply power to all busbars. Even if all energy storage units fail, automatic transfer switches can quickly switch to uninterruptible power supply, forming redundant protection, completely avoiding the risk of power loss for critical loads, and achieving a dual improvement in power supply continuity and stability.

[0082] Furthermore, before closing the tie switch connecting the faulty section switch station bus and the normal section switch station bus, a synchronization check is performed to ensure that the voltage, frequency, and phase of the faulty section switch station bus and the normal section switch station bus are consistent.

[0083] Specifically, the synchronization check is a core pre-processing step to ensure the safe grid connection of the faulty busbar and the normal busbar. First, it collects the voltage amplitude, frequency, and phase values ​​of the faulty and normal busbars in real time. Second, it calculates the differences in similar parameters between the two busbars, obtaining the voltage amplitude difference, frequency difference, and phase difference, and compares them with preset safety thresholds. Only when the differences in all three parameters consistently meet the safety thresholds is the synchronization check determined to be satisfied, and a closing command is sent to the tie switch. If any parameter difference exceeds the threshold, the synchronization check module triggers a synchronization condition failure signal, prohibiting the tie switch from closing and continuously monitoring parameter changes until the condition is satisfied. This operation completely eliminates the closing inrush current caused by parameter inconsistencies between the busbars, preventing damage to busbar-side equipment, grid-type energy storage units, and normal grid power supply units. It also ensures a smooth power connection between the two busbars after closing, without sudden voltage spikes or drops, guaranteeing the stability of the load power supply.

[0084] Furthermore, the automatic transfer switch monitors the voltage of each section of the switch station bus at the input terminal in real time. When it detects that the current power supply switch station bus is undervoltage, it switches the load to be powered by another normal switch station bus. During the switching process, the uninterruptible power supply maintains continuous power supply to the load.

[0085] Specifically, the input of the automatic transfer switch continuously collects voltage signals from the busbars of each connected switch station and compares them in real time with a preset normal voltage range to determine the power supply status of each busbar. When the automatic transfer switch detects an abnormality such as undervoltage or overvoltage on the busbar currently supplying the load, it immediately triggers a switching procedure. At this time, due to the millisecond-level switching delay between the automatic transfer switch disconnecting the current busbar and closing the target normal busbar, the uninterruptible power supply (UPS) simultaneously detects voltage fluctuations at the output of the automatic transfer switch and immediately initiates a seamless power supply mode: if it is an online UPS, it is always in inverter mode and can directly maintain a stable output voltage without power interruption; if it is a standby UPS, it will start the inverter after detecting an input power failure to replace the input power of the automatic transfer switch and supply power to the load. After the automatic transfer switch completes the switching, successfully connects to the normal busbar, and outputs a stable voltage, the UPS will detect that the input has returned to normal, gradually exit the power supply state, and switch back to the float charging standby mode. This collaborative mechanism can achieve zero interruption of load power supply, and is especially suitable for scenarios with extremely high requirements for power supply continuity, such as data centers and medical equipment.

[0086] Furthermore, when all grid-connected energy storage units are operating off-grid in parallel, a master-slave control or droop control strategy is adopted to stabilize the voltage and frequency of all switch station buses.

[0087] Specifically, when all grid-connected energy storage units switch to off-grid mode and operate in parallel, the selection and implementation of master-slave control and droop control strategies need to be considered in conjunction with the number of energy storage units, communication conditions, and system stability requirements. The specific operational details are as follows:

[0088] 1. Master-slave control strategy

[0089] First, the system determines one master-grid type energy storage unit through preset logic (such as by energy storage unit capacity, access location priority, or random selection), with the rest being slave-grid type energy storage units. The master energy storage unit adopts V / f (voltage / frequency) control mode, autonomously setting and maintaining the system's rated voltage and frequency as the voltage and frequency benchmark for the entire off-grid system. The slave energy storage units adopt PQ (power / reactive power) control mode, receiving voltage and frequency signals from the master energy storage unit in real time, and adjusting their output active and reactive power according to their own capacity and system load requirements. Simultaneously, the slave energy storage units compare their own output voltage and frequency with the master energy storage unit's benchmark values ​​in real time, automatically correcting any deviations to ensure that the output parameters of all energy storage units are consistent with those of the master energy storage unit. This strategy offers high control precision and is suitable for scenarios with a small number of energy storage units and stable communication links, enabling rapid balanced distribution of load power.

[0090] 2. Sagging Control Strategy

[0091] This strategy eliminates the need for master-slave energy storage units. Each grid-type energy storage unit autonomously adjusts its output parameters using preset droop characteristic curves. The "active power-frequency droop curve" specifies that when system load increases leading to a frequency decrease, the energy storage unit increases active power output proportionally; conversely, when load decreases leading to a frequency increase, it decreases active power output proportionally to maintain system frequency stability. The "reactive power-voltage droop curve" specifies that when reactive load increases leading to a voltage decrease, the energy storage unit increases reactive power output proportionally; conversely, when reactive load decreases leading to a voltage increase, it decreases reactive power output proportionally to maintain system voltage stability. Each energy storage unit autonomously adjusts its power output based on its own detected bus voltage and frequency changes, without relying on a communication link. Even if one energy storage unit fails, the remaining units can automatically share the load through droop characteristics, ensuring stable system operation. This decentralized and highly reliable strategy is suitable for scenarios with a large number of energy storage units and limited communication capabilities, enhancing the system's anti-interference ability and scalability.

[0092] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0093] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0094] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power supply system incorporating grid-type energy storage, characterized in that, include: Multiple power grid supply units from different sources, each power grid supply unit is connected to an independent switch station bus through an incoming line switch; Multiple switchyard buses, adjacent switchyard buses are connected by tie switches; At least one grid-type energy storage unit, each of the grid-type energy storage units being connected to at least one section of the switch station bus via an energy storage switch, the grid-type energy storage unit being configured to switch between grid-connected mode and off-grid mode, and providing voltage and frequency support to the connected switch station bus in off-grid mode; Automatic transfer switches, with their input terminals connected to at least two different sections of the switch station bus in the bus network; An uninterruptible power supply (UPS) has its input terminal connected to the output terminal of the automatic transfer switch, and its output terminal connected to the load.

2. The system according to claim 1, characterized in that, The multi-source power grid supply unit includes three power grid supply units, which are respectively connected to the first switch station bus, the second switch station bus, and the third switch station bus; The grid-type energy storage unit includes a first grid-type energy storage unit and a second grid-type energy storage unit. The first grid-type energy storage unit is connected to the first switch station bus, and the second grid-type energy storage unit is connected to the third switch station bus. The tie switch includes a first tie switch and a second tie switch. The first tie switch is connected between the first switch station bus and the second switch station bus, and the second tie switch is connected between the second switch station bus and the third switch station bus.

3. The system according to claim 1, characterized in that, The connecting switch is a circuit breaker with synchronization detection and closing function.

4. The system according to claim 1, characterized in that, When the grid-type energy storage unit detects that the incoming switch of the connected switch station bus has tripped, it switches from grid-connected mode to off-grid mode and provides independent voltage and frequency support for the connected switch station bus.

5. The system according to claim 1, characterized in that, The automatic transfer switch monitors the voltage status of each connected switch station bus in real time, and automatically switches to another normal switch station bus when it detects that the currently powered switch station bus is undervoltage.

6. The system according to claim 1, characterized in that, The uninterruptible power supply switches to battery mode to continuously supply power to the load during the automatic transfer switch switching process or when all switch station buses lose voltage.

7. A power supply operation method, applied to a power supply system containing grid-type energy storage as described in any one of claims 1-6, characterized in that, include: During normal system operation, multiple power grid supply units operate separately with their respective corresponding switch station buses, and the grid-type energy storage unit operates in grid-connected mode. When a fault in a power grid unit causes the incoming switch to trip, the fault section grid-type energy storage unit connected to the busbar of the fault section switch station corresponding to the tripped incoming switch switches switches to off-grid mode to support the busbar voltage of the fault section switch station. After the system stabilizes, the interconnection switch connecting the busbar of the faulty section switch station and the busbar of the normal section switch station is closed. The normal grid power supply unit adjacent to the faulty grid power supply unit drives the busbar of the faulty section switch station, and the grid-type energy storage unit of the faulty section resumes grid connection mode. When all grid power supply units fail, all grid-type energy storage units switch to off-grid mode and operate in parallel to supply power to all switch station buses. When all grid-type energy storage units fail and go out of service, the load is powered by an uninterruptible power supply through an automatic transfer switch.

8. The method according to claim 7, characterized in that, Before closing the tie switch connecting the faulty section switch station bus and the normal section switch station bus, a synchronization check is performed to ensure that the voltage, frequency and phase of the faulty section switch station bus and the normal section switch station bus are consistent.

9. The method according to claim 7, characterized in that, The automatic transfer switch monitors the voltage of each section of the switch station bus at the input terminal in real time. When it detects that the current switch station bus is undervoltage, it switches the load to be powered by another normal switch station bus. During the switching process, the uninterruptible power supply maintains continuous power supply to the load.

10. The method according to claim 7, characterized in that, When all grid-connected energy storage units are operating off-grid in parallel, a master-slave control or droop control strategy is adopted to stabilize the voltage and frequency of all switch station buses.

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