Anti-interference electricity energy storage system and control method thereof

Abstract

The invention discloses an anti-interference electricity energy storage system and a control method thereof. The anti-interference electricity energy storage system comprises a power grid access module and an intelligent monitoring control module, the intelligent monitoring control module is connected with the power grid access module, a dynamic voltage restorer, a super capacitor, an energy storage converter and a switching device, and the intelligent monitoring control module is used for controlling the dynamic voltage restorer and the super capacitor to work cooperatively when short-time interference electricity of a power grid is detected. Performing voltage compensation on the load bus; the intelligent monitoring control module is also used for controlling the energy storage converter to start and switch to an inversion mode when the power sag duration exceeds the supporting duration of the super capacitor or the charge state of the super capacitor is reduced to be below a preset threshold value, converting the electric energy of the battery box into alternating current and outputting the alternating current to a load bus; and the dynamic voltage restorer and the super capacitor are replaced to supply power to the load bus. According to the invention, rapid voltage compensation for short-time interference electricity and continuous and stable power supply for long-time interference electricity can be realized, the purchase, installation and maintenance costs are reduced, and the compatibility is good.

Description

Technical Field

[0001] This invention relates to the field of energy storage control technology, and in particular to an anti-power fluctuation energy storage system and its control method. Background Technology

[0002] Figure 1 This is a schematic diagram of a traditional anti-power fluctuation system, such as... Figure 1 As shown, traditional anti-voltage fluctuation systems have significant shortcomings: relying solely on short-term energy storage components such as supercapacitors and small-capacity batteries, the power supply duration can only last for a few seconds to tens of seconds, only addressing short-term voltage fluctuation scenarios. Once a prolonged power outage occurs, the power supply cannot be sustained, still causing load shutdowns. Functionally, they only have the single function of short-term voltage compensation, unable to achieve energy storage, peak shaving, or other power management operations, nor can they generate additional revenue such as peak-valley arbitrage, resulting in high daily idle rates. Load coverage is mostly limited to local small-power devices, and adapting to centralized loads at the park level requires the deployment of multiple independent systems, which is costly and lacks unified power supply management capabilities. At the same time, they can only deal with short-term voltage fluctuation faults and cannot handle complex power supply risks such as continuous low voltage on the grid and prolonged power outages. In the long run, they only solve a single pain point of voltage fluctuation, resulting in a low return on investment.

[0003] Figure 2 This is a schematic diagram of the structure of an existing traditional energy storage system, such as... Figure 2 As shown, pure energy storage systems have core shortcomings: their power conversion systems (PCS) typically have a response speed in the hundreds of milliseconds, which cannot match the rapid response requirements of "power dips" (millisecond-level voltage fluctuations). When faced with short-term voltage drops / interruptions, they cannot achieve imperceptible voltage compensation, which can lead to shutdowns of industrial loads due to power dips. At the same time, pure energy storage systems only have long-term energy storage, backup power supply, or peak power regulation functions, and lack dedicated short-term voltage management modules, such as dynamic voltage restorers (DVRs). They cannot cover the pain points of "power dips" that occur frequently in industrial scenarios, and their power supply stability guarantee for production equipment is not comprehensive. In addition, their functions focus on the storage and transfer of electrical energy and are not adapted to typical industrial power supply risks such as short-term voltage fluctuations. They cannot take into account the full-scenario power supply guarantee of "short-term power dips + long-term power outages". In the actual application of industrial production loads, the coverage of power supply risk resistance is narrow.

[0004] In summary, traditional power systems suffer from short-term support time for anti-sloshing equipment, single-use energy storage systems, and high costs and poor compatibility when deployed independently. Summary of the Invention

[0005] This invention provides an anti-voltage fluctuation energy storage system and its control method, which can achieve rapid voltage compensation for short-term voltage fluctuations and continuous and stable power supply for long-term voltage fluctuations, ensuring uninterrupted operation of the load, reducing equipment procurement, installation and maintenance costs, and has good compatibility.

[0006] According to one aspect of the present invention, an anti-power fluctuation energy storage system is provided, the anti-power fluctuation energy storage system comprising: a grid access module for connecting to an external power grid; A dynamic voltage restorer is connected between the power grid access module and the load bus to compensate the voltage of the load bus when the power grid voltage is abnormal. A supercapacitor, connected to the DC side of the dynamic voltage restorer, is used to provide short-term, rapid electrical support to the dynamic voltage restorer. An energy storage converter, the AC side of which is connected to the load bus via a switching device; The battery box is connected to the DC side of the energy storage converter and is used to store and release electrical energy; The intelligent monitoring and control module is connected to the grid access module, the dynamic voltage restorer, the supercapacitor, the energy storage converter, and the switching device, respectively. The intelligent monitoring and control module is used to control the dynamic voltage restorer and the supercapacitor to work together to compensate the voltage of the load bus when a short-term power dip is detected in the grid. The intelligent monitoring and control module is also used to control the energy storage converter to start and switch to inverter mode when the duration of the voltage fluctuation exceeds the support time of the supercapacitor or when the state of charge of the supercapacitor drops below a preset threshold, so as to convert the electrical energy of the battery box into AC power and output it to the load bus, so as to replace the dynamic voltage restorer and the supercapacitor to supply power to the load bus.

[0007] Optionally, the anti-voltage fluctuation energy storage system further includes: a bidirectional thyristor switch, the bidirectional thyristor switch being connected between the dynamic voltage restorer and the load bus, and the intelligent monitoring and control module being connected to the bidirectional thyristor switch. The intelligent monitoring and control module is used to control the bidirectional thyristor switch to turn on when the power grid is normal, so that the dynamic voltage restorer is bypassed. The intelligent monitoring and control module is used to control the bidirectional thyristor switch to quickly turn off when a power dip is detected in the power grid, so as to enable the dynamic voltage restorer.

[0008] Optionally, the intelligent monitoring and control module is also used to control the bidirectional thyristor switch to turn on while the energy storage converter is supplying power to the load bus.

[0009] Optionally, the anti-power fluctuation energy storage system further includes: a grid connection switch, wherein the grid connection switch is disposed between the grid access module and the energy storage converter; The intelligent monitoring and control module is connected to the grid-connected switch. Before controlling the energy storage converter to start emergency power supply, the intelligent monitoring and control module controls the grid-connected switch to disconnect, so as to isolate the load bus from the abnormal power grid.

[0010] Optionally, the intelligent monitoring and control module is also used to control the energy storage converter to switch to grid-connected mode and synchronize with the grid after detecting that the grid voltage has returned to stability, control the grid-connected switch to close, control the energy storage converter to reduce the output power, switch the power supply of the load bus to be provided by the grid, and control the energy storage converter to switch to rectification mode to use the grid's electrical energy to charge the battery box.

[0011] Optionally, during periods when the power grid is normal and there is a peak-valley electricity price difference, the intelligent monitoring and control module is also used to control the energy storage converter to charge the battery box during the off-peak electricity price period and control the battery box to discharge through the energy storage converter during the peak electricity price period.

[0012] Optionally, the anti-power fluctuation energy storage system also includes: a first bypass switch and a second bypass switch; The first bypass switch is connected in parallel with the grid-connected switch. The first bypass switch is used to close the grid-connected switch when it malfunctions or fails, ensuring that the grid-connected switch is out of service while the load bus is powered normally. The second bypass switch is connected in parallel with the bidirectional thyristor switch. The second bypass switch is used to close the circuit when the bidirectional thyristor switch malfunctions or fails, ensuring that the bidirectional thyristor switch stops operating while the load bus is powered normally.

[0013] According to another aspect of the present invention, a control method for an anti-power fluctuation energy storage system is provided, applied to the anti-power fluctuation energy storage system described in any one of the preceding aspects, the method comprising: The intelligent monitoring and control module monitors the grid voltage status in real time. When a voltage dip or short-term interruption is detected in the power grid, it is determined to be a voltage drop, and a short-term compensation mode is entered. The dynamic voltage restorer is activated and the power of the supercapacitor is used to compensate the voltage of the load bus. The intelligent monitoring and control module continuously monitors the power sag and the support capacity of the supercapacitor. When a prolonged power slump is detected, the system switches to energy storage emergency mode, activates the inverter function of the energy storage converter, and uses the power of the battery box to supply power to the load bus. Once the grid voltage is detected to have stabilized, a system reset operation is performed, switching to the normal grid power supply mode.

[0014] Optionally, before entering the energy storage emergency mode, the method further includes disconnecting the load bus from the power grid.

[0015] Optionally, the system reset operation includes: After synchronizing the energy storage converter with the power grid, the power supply to the load bus is switched back to the power grid. The energy storage converter is controlled to charge the battery box to replenish the electrical energy consumed during emergency power supply.

[0016] The technical solution of this invention utilizes supercapacitors in conjunction with dynamic voltage restorers to achieve short-term power fluctuation compensation with millisecond-level response, and utilizes battery boxes and energy storage converters to provide long-term (up to several hours) emergency power supply. Intelligent control enables seamless and smooth switching between the two, comprehensively covering various voltage quality issues from milliseconds to hours. It fully leverages the high power density, long cycle life, and fast response speed of supercapacitors to cope with short-term impacts, and the high energy density and long-term endurance of batteries to cope with long-term power supply. The overall system achieves an optimal combination in terms of dynamic performance, support duration, and economy. It overcomes the limitations of traditional independent deployment of anti-power fluctuation equipment and energy storage systems, integrating short-term emergency and long-term protection functions into one unit, reducing equipment procurement, installation, and maintenance costs, and improving system space utilization. In summary, this invention solves the problems of short support time for anti-power fluctuation equipment in traditional power systems, the reliance on separate energy storage systems, and the high cost and poor compatibility of independent deployment. It achieves rapid voltage compensation for short-term power fluctuations and continuous and stable power supply for long-term power fluctuations, ensuring uninterrupted load operation, reducing equipment procurement, installation, and maintenance costs, and providing good compatibility.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a conventional anti-power fluctuation system.

[0020] Figure 2 This is a schematic diagram of the structure of an existing traditional energy storage system; Figure 3 This is a schematic diagram of the structure of an anti-power fluctuation energy storage system provided according to an embodiment of the present invention; Figure 4 This is a flowchart of a control method for an anti-power fluctuation energy storage system provided according to an embodiment of the present invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0023] Figure 3 This is a schematic diagram of an anti-power fluctuation energy storage system according to an embodiment of the present invention. (Refer to...) Figure 3 An embodiment of the present invention provides an anti-power fluctuation energy storage system, which includes: a grid access module 1 for connecting to an external power grid; The dynamic voltage restorer 2 is connected between the grid access module 1 and the load bus 7 and is used to compensate the voltage of the load bus 7 when the grid voltage is abnormal. Supercapacitor 3 is connected to the DC side of dynamic voltage restorer 2 to provide short-term and rapid power support for dynamic voltage restorer 2; The energy storage converter 4 is connected to the load bus 7 on its AC side via switching devices; Battery box 5 is connected to the DC side of energy storage converter 4 and is used to store and release electrical energy; The intelligent monitoring and control module 6 is connected to the grid access module 1, the dynamic voltage restorer 2, the supercapacitor 3, the energy storage converter 4, and the switching device, respectively. The intelligent monitoring and control module 6 is used to control the dynamic voltage restorer 2 and the supercapacitor 3 to work together to compensate the voltage of the load bus 7 when a short-term voltage drop is detected in the grid. The intelligent monitoring and control module 6 is also used to control the energy storage converter 4 to start and switch to inverter mode when the power slump lasts longer than the support time of the supercapacitor 3 or when the state of charge of the supercapacitor 3 drops below a preset threshold. This allows the energy of the battery box 5 to be converted into AC power and output to the load bus 7, so as to replace the dynamic voltage restorer 2 and the supercapacitor 3 in supplying power to the load bus 7.

[0024] Specifically, the grid access module 1 is used to connect to an external three-phase or single-phase power grid and may include components such as circuit breakers, fuses, surge protectors, and transformers. The input of the dynamic voltage restorer 2 is connected to the power grid via the grid access module 1, and its output is connected to the load bus 7 via a line. Its core is a voltage source inverter, which can quickly generate compensation voltage and inject it into the grid in series according to instructions to maintain the stability of the load bus 7 voltage. The supercapacitor 3 is directly connected in parallel to the DC bus of the dynamic voltage restorer 2, serving as the DC-side support power source for the dynamic voltage restorer 2. Its high power density and fast charge / discharge characteristics enable it to provide the energy required for high-power compensation to the dynamic voltage restorer 2 within milliseconds. The energy storage converter 4 is a bidirectional AC / DC converter, with its AC side connected to the load bus 7 via a contactor or circuit breaker. The battery box 5, typically composed of lithium-ion batteries, is connected to the DC side of the energy storage converter 4. The intelligent monitoring and control module 6 is the "brain" of the system. It collects voltage and current signals from the grid side and the load side in real time through voltage and current sensors, and communicates and controls the management units of the dynamic voltage restorer 2, energy storage converter 4, supercapacitor 3, and various switching devices.

[0025] Anti-flicker energy storage systems can break down the complete operation logic into 6 stages, clearly defining the triggering conditions and equipment actions for each step: Phase 1: Normal operation (no power fluctuation).

[0026] Equipment status: Grid voltage is stable; Dynamic voltage restorer 2 is bypassed and in standby mode; 400Vac load bus 7 is directly powered by the grid; Energy storage converter 4 is in standby mode; Battery box 5 maintains high SOC (for peak-valley arbitrage); Supercapacitor 3 is fully charged and in standby mode.

[0027] Phase 2: Power sway trigger + short-term compensation.

[0028] Triggering conditions: Grid voltage drop / interruption (power fluctuation), duration ≤ support time of supercapacitor 3 (e.g., ≤5 seconds); Equipment action: Intelligent monitoring and control module 6 issues command, switching device quickly disconnects, cutting off the bypass of dynamic voltage restorer 2; dynamic voltage restorer 2 starts, supercapacitor 3 discharges, compensates the load bus voltage, and maintains load power supply.

[0029] Phase 3: Long-term power slump detection (triggers energy storage intervention).

[0030] Triggering conditions: The duration of the power fluctuation exceeds the support time of supercapacitor 3, or the SOC of supercapacitor 3 drops below 20%; Equipment action: The anti-power fluctuation energy storage system triggers the "energy storage emergency power supply command".

[0031] Phase 4: Emergency intervention of energy storage converter 4.

[0032] Equipment operation: First, disconnect the switching device (to prevent the energy storage converter 4 from connecting to the faulty grid in case of grid abnormality, thus ensuring equipment safety); the energy storage converter 4 switches from "standby" to "inverter mode", and uses the power from the battery box 5 to invert 400Vac AC power.

[0033] Phase 5: Long-term power supply maintenance.

[0034] Equipment operation: The 400Vac output of the energy storage converter 4 is connected to the load bus, replacing the supercapacitor 3 and the dynamic voltage restorer 2 to support the load voltage; the dynamic voltage restorer 2 stops compensation and switches back to standby mode; the supercapacitor 3 stops discharging and will be recharged after the grid is restored.

[0035] Phase 6: Reset and power replenishment after grid restoration.

[0036] Triggering condition: The intelligent monitoring and control module 6 detects that the grid voltage has returned to stability (lasting ≥1 second); Equipment Actions: Close the switching device and switch the energy storage converter 4 to "grid-connected mode" to synchronize with the grid; gradually reduce the output power of the energy storage converter 4 to return the power supply to the grid; switch the energy storage converter 4 to "rectification mode" to use off-peak electricity (or current low-priced electricity) to charge the battery box 5 and restore the battery SOC to the target value.

[0037] The anti-power fluctuation energy storage system has an adaptive power supply mode and can automatically switch between the following three working modes according to the grid status: under normal conditions, the grid directly supplies power and the energy storage is in standby mode; during short-term power fluctuations, the dynamic voltage restorer and supercapacitor provide emergency power; during long-term power fluctuations, the energy storage converter provides emergency power; after the grid is restored, it automatically returns to the normal mode and starts energy storage to replenish energy without manual intervention.

[0038] The technical solution of this invention utilizes supercapacitors in conjunction with dynamic voltage restorers to achieve short-term power fluctuation compensation with millisecond-level response, and utilizes battery boxes and energy storage converters to provide long-term (up to several hours) emergency power supply. Intelligent control enables seamless and smooth switching between the two, comprehensively covering various voltage quality issues from milliseconds to hours. It fully leverages the high power density, long cycle life, and fast response speed of supercapacitors to cope with short-term impacts, and the high energy density and long-term endurance of batteries to cope with long-term power supply. The overall system achieves an optimal combination in terms of dynamic performance, support duration, and economy. It overcomes the limitations of traditional independent deployment of anti-power fluctuation equipment and energy storage systems, integrating short-term emergency and long-term protection functions into one unit, reducing equipment procurement, installation, and maintenance costs, and improving system space utilization. In summary, this invention solves the problems of short support time for anti-power fluctuation equipment in traditional power systems, the reliance on separate energy storage systems, and the high cost and poor compatibility of independent deployment. It achieves rapid voltage compensation for short-term power fluctuations and continuous and stable power supply for long-term power fluctuations, ensuring uninterrupted load operation, reducing equipment procurement, installation, and maintenance costs, and providing good compatibility.

[0039] Continue to refer to Figure 3 Optionally, the anti-power fluctuation energy storage system also includes: a bidirectional thyristor switch 8, which is connected between the dynamic voltage restorer 2 and the load bus 7, and an intelligent monitoring and control module 6 is connected to the bidirectional thyristor switch 8. The intelligent monitoring and control module 6 is used to control the bidirectional thyristor switch 8 to conduct when the power grid is normal, so that the dynamic voltage restorer 2 is bypassed. The intelligent monitoring and control module 6 is used to control the bidirectional thyristor switch 8 to quickly shut down when a power dip is detected in the power grid, so as to enable the dynamic voltage restorer 2.

[0040] Specifically, a bidirectional thyristor switch 8, controlled by the intelligent monitoring and control module 6, is connected in series between the output terminal of the dynamic voltage restorer 2 and the load bus 7. When the power grid is normal, the bidirectional thyristor switch 8 is turned on, bypassing the inverter-side output bridge arm of the dynamic voltage restorer 2. The current flows directly to the load through the thyristor, avoiding conduction losses in the power devices of the dynamic voltage restorer 2 and improving system efficiency. Once a voltage dip is detected, the intelligent monitoring and control module 6 issues a command to quickly turn off the bidirectional thyristor switch 8 at the current zero-crossing point, forcing the load current to flow through the dynamic voltage restorer 2, which then begins operation.

[0041] Continue to refer to Figure 3 Optionally, the intelligent monitoring and control module 6 is also used to control the bidirectional thyristor switch 8 to conduct during the period when the energy storage converter 4 supplies power to the load bus 7.

[0042] Specifically, when the energy storage converter 4 intervenes in an emergency, the 400Vac output of the energy storage converter 4 is connected to the load bus 7, replacing the supercapacitor 3 and the dynamic voltage restorer 2 to supply power to the load; the bidirectional thyristor switch 8 is closed, at which time the bidirectional thyristor switch 8 serves as the path for the energy storage converter 4 to supply power to the load bus 7, reducing circuit losses.

[0043] Continue to refer to Figure 3 Optionally, the anti-power fluctuation energy storage system also includes: a grid connection switch 9, which is installed between the grid access module 1 and the energy storage converter 4; The intelligent monitoring and control module 6 is connected to the grid-connected switch 9. The intelligent monitoring and control module 6 is used to control the grid-connected switch 9 to disconnect before controlling the energy storage converter 4 to start emergency power supply, so as to achieve isolation between the load bus 7 and the abnormal power grid.

[0044] Specifically, a grid connection switch 9 is also installed between the grid access module 1 and the load bus 7. When a long-term emergency power supply is required from the energy storage converter 4 and the battery box 5, the intelligent monitoring and control module 6 will first issue a command to disconnect this grid connection switch 9, so that the load bus 7 is isolated from the faulty grid, forming an islanded operation mode in which the system supplies power independently.

[0045] Continue to refer to Figure 3 Optionally, the intelligent monitoring and control module 6 is also used to control the energy storage converter 4 to switch to grid-connected mode and synchronize with the grid after the grid voltage is detected to have returned to stability, control the grid-connected switch 9 to close, control the energy storage converter 4 to reduce the output power, switch the power supply of the load bus to be provided by the grid, and control the energy storage converter 4 to switch to rectification mode to use the power of the grid to charge the battery box.

[0046] Specifically, the intelligent monitoring and control module 6 detects that the grid voltage has stabilized (lasting ≥1 second); it closes the grid connection switch 9 and switches the energy storage converter 4 to "grid connection mode" to synchronize with the grid; the energy storage converter 4 gradually reduces its output power and returns the power supply to the grid; the energy storage converter 4 switches to "rectification mode" to use off-peak electricity (or current low-priced electricity) to charge the battery box 5 and restore the battery SOC to the target value.

[0047] Continue to refer to Figure 3 Optionally, during periods when the power grid is normal and there is a peak-valley electricity price difference, the intelligent monitoring and control module 6 is also used to control the energy storage converter 4 to charge the battery box 5 during the off-peak electricity price period and control the battery box 5 to discharge through the energy storage converter 4 during the peak electricity price period.

[0048] Specifically, under the condition of long-term grid stability, the intelligent monitoring and control module 6 can control the energy storage converter 4 and the battery box 5 to charge during valley hours and discharge during peak hours according to the preset peak-valley electricity price schedule, so as to achieve economic and optimized operation.

[0049] By implementing peak-valley arbitrage as described above, and ensuring power security, the system generates continuous economic benefits for users through the peak-valley charging and discharging scheduling of a 5MWh high-capacity energy storage battery. This addresses the pain point of traditional anti-power fluctuation equipment, which only involves investment without output, and offers the advantages of both economy and reliability. When the grid is normal, the system can switch to conventional energy storage mode to perform peak shaving and valley filling, demand management, and other applications, generating additional revenue, improving the return on investment, and providing multi-functional, economical, and efficient operation.

[0050] Anti-power fluctuation energy storage systems are suitable for scenarios with high requirements for power supply stability and large power consumption, including but not limited to: chemical industrial parks, semiconductor factories, precision manufacturing workshops, data centers, new energy industrial parks, etc. They are especially suitable for areas with frequent power grid fluctuations and significant peak-valley electricity price differences, and can simultaneously meet users' power security needs and cost reduction and efficiency improvement needs.

[0051] Continue to refer to Figure 3 Optionally, the anti-sloshing energy storage system also includes: a first bypass switch 10 and a second bypass switch 11; The first bypass switch 10 is connected in parallel with the grid-connected switch 9. The first bypass switch 10 is used to close the grid-connected switch 9 when there is an abnormality or fault, so as to ensure that the grid-connected switch 9 is out of service while the load bus is powered normally. The second bypass switch 11 is connected in parallel with the bidirectional thyristor switch 8. The second bypass switch 11 is used to close the circuit when the bidirectional thyristor switch 8 is abnormal or faulty, so as to ensure that the bidirectional thyristor switch 8 is out of service while the load bus is powered normally.

[0052] Specifically, to further enhance reliability, a first bypass switch 10 can be connected in parallel with the grid-connected switch 9, and a second bypass switch 11 can be connected in parallel with the bidirectional thyristor switch 8. When the grid-connected switch 9 or the bidirectional thyristor switch 8 fails to operate normally, the power supply path can be ensured by closing the corresponding bypass switch, facilitating maintenance of the faulty switch. By designing multiple safeguards such as the grid-connected switch 9, the first bypass switch 10, and the second bypass switch 11, the power supply to the load bus is ensured to remain uninterrupted in the event of any single-point failure, resulting in high system reliability and ease of maintenance.

[0053] Continue to refer to Figure 3 The anti-surge energy storage system adopts a layered architecture design, which is divided into the grid access layer, core control layer, function execution layer and load side from top to bottom. Each module has a clear responsibility and achieves real-time linkage through a communication bus. The specific composition and functions are as follows: Anti-flicker energy storage systems can break down the complete operation logic into 6 stages, clearly defining the triggering conditions and equipment actions for each step: Phase 1: Normal operation (no power fluctuation).

[0054] Equipment status: Grid voltage is stable; bidirectional thyristor switch 8 (dynamic voltage restorer 2 bypass) is on, dynamic voltage restorer 2 is on standby; grid connection switch 9 is closed, 400Vac load bus 7 is directly powered by the grid; energy storage converter 4 is on standby, battery box 5 maintains high SOC (peak-valley arbitrage backup); supercapacitor 3 is fully charged and on standby.

[0055] Phase 2: Power sway trigger + short-term compensation.

[0056] Triggering conditions: Grid voltage drop / interruption (power fluctuation), duration ≤ support time of supercapacitor 3 (e.g., ≤ 5 seconds); Equipment action: Intelligent monitoring and control module 6 issues command, bidirectional thyristor switch 8 quickly disconnects (cuts off the bypass of dynamic voltage restorer 2); dynamic voltage restorer 2 starts, supercapacitor 3 discharges, compensates for load bus voltage, and maintains load power supply.

[0057] Phase 3: Long-term power slump detection (triggers energy storage intervention).

[0058] Triggering conditions: The duration of the power fluctuation exceeds the support time of supercapacitor 3, or the SOC of supercapacitor 3 drops below 20%; Equipment action: The anti-power fluctuation energy storage system triggers the "energy storage emergency power supply command".

[0059] Phase 4: Emergency intervention of energy storage converter 4.

[0060] Equipment Action: First, disconnect the grid connection switch 9 (to prevent the energy storage converter 4 from connecting to the faulty grid when the grid is abnormal, thus ensuring equipment safety); the energy storage converter 4 switches from "standby" to "inverter mode", and uses the power from the battery box 5 to invert 400Vac AC power.

[0061] Phase 5: Long-term power supply maintenance.

[0062] Equipment operation: The 400Vac output of the energy storage converter 4 is connected to the load bus, replacing the supercapacitor 3 and the dynamic voltage restorer 2 to support the load voltage; the bidirectional thyristor switch 8 is closed (at this time, the bidirectional thyristor switch 8 serves as the path for the energy storage converter 4 to supply power to the load bus 7, reducing circuit losses); the dynamic voltage restorer 2 stops compensation and switches back to standby mode; the supercapacitor 3 pauses discharging and will be recharged after the grid is restored.

[0063] Phase 6: Reset and power replenishment after grid restoration.

[0064] Triggering conditions: The intelligent monitoring and control module 6 detects that the grid voltage has stabilized (lasting ≥1 second); Equipment action: Close the grid connection switch 9, switch the energy storage converter 4 to "grid connection mode" and synchronize with the grid first; the energy storage converter 4 gradually reduces the output power and returns the power supply to the grid; the energy storage converter 4 switches to "rectification mode" and uses off-peak electricity (or current low-priced electricity) to charge the battery box 5 and restore the battery SOC to the target value.

[0065] The above logic enables full-scenario anti-power fluctuations, with "short-term power fluctuations relying on supercapacitor 3 and dynamic voltage restorer 2, and long-term power fluctuations relying on energy storage converter 4", while also connecting to subsequent energy replenishment from energy storage.

[0066] The anti-power fluctuation energy storage system is a multi-functional integrated power protection system designed for industrial parks and highly sensitive load scenarios. Its core lies in the deep integration of two major functions: short-term anti-power fluctuation emergency protection and long-term energy storage peak-valley arbitrage. Through modular design and intelligent collaborative control, it solves the technical pain points of traditional power systems, such as short support time for anti-power fluctuation equipment, arbitrage of energy storage systems alone, high cost and poor compatibility of independent deployment of the two.

[0067] The anti-power fluctuation energy storage system uses the power grid as the access point and the bus as the core power supply link. Through the coordinated action of dynamic voltage restorers, supercapacitors, thyristors, bypass switches, energy storage converters, large-capacity battery boxes, and intelligent monitoring and control modules, it can achieve millisecond-level response to power grid fluctuations (voltage dips / short-term interruptions) and ensure uninterrupted operation of loads. It can also realize arbitrage of electricity price differences through peak-valley charging and discharging scheduling of the energy storage system. At the same time, it can seamlessly switch to energy storage emergency power supply in long-term power fluctuation scenarios, forming a three-in-one power solution of "short-term emergency + long-term protection + economic benefits".

[0068] The anti-ghosting energy storage system breaks through the limitations of traditional anti-ghosting equipment and energy storage systems being deployed independently. It integrates short-term emergency response, long-term protection, and peak-valley arbitrage functions into one system, reducing equipment procurement, installation, and maintenance costs, and improving system space utilization.

[0069] The embodiments of the present invention also provide a control method for an anti-power fluctuation energy storage system, applicable to the anti-power fluctuation energy storage system in any embodiment of the present invention. Figure 4 This is a flowchart of a control method for an anti-power fluctuation energy storage system according to an embodiment of the present invention, with reference to... Figure 4 The control methods for anti-power fluctuation energy storage systems include: S110: Monitors the grid voltage status in real time through the intelligent monitoring and control module.

[0070] Specifically, in combination Figure 3The system initializes and continues to operate in normal grid mode. The intelligent monitoring and control module 6 samples and analyzes the grid voltage in real time at high speed. At this time, the bidirectional thyristor switch 8 is turned on, and the dynamic voltage restorer 2 is bypassed; the grid-connected switch 9 is closed, and the grid supplies power to the load normally; the energy storage converter 4 may be in standby, charging, or grid-connected discharging (peak-valley arbitrage) state.

[0071] S120. When a voltage dip or short-term interruption is detected in the power grid, it is determined to be a voltage drop. The system enters short-term compensation mode, activates the dynamic voltage restorer, and uses the power of the supercapacitor to compensate the voltage of the load bus.

[0072] Specifically, in combination Figure 3 When the intelligent monitoring and control module 6 detects that the grid voltage amplitude is lower than a preset threshold (such as 90% of the nominal value), it determines that a voltage dip has occurred and immediately enters the short-time compensation mode. In the short-time compensation mode, the intelligent monitoring and control module 6 issues a command to quickly shut off the bidirectional thyristor switch 8 and simultaneously activate the dynamic voltage restorer 2. The dynamic voltage restorer 2 generates a corresponding compensation voltage through its inverter based on the detected voltage drop depth and phase. Its energy is provided instantaneously by the supercapacitor 3, thereby compensating the voltage of the load bus 7 to the normal level in a very short time.

[0073] S130 continuously monitors the power sag and the supercapacitor's support capacity through an intelligent monitoring and control module.

[0074] Specifically, in combination Figure 3 During the compensation process, the intelligent monitoring and control module 6 continuously monitors whether the grid voltage is restored, and at the same time monitors the terminal voltage or state of charge of the supercapacitor 3.

[0075] S140. When it is determined that a long-term power slump has occurred, switch to the energy storage emergency mode, start the inverter function of the energy storage converter, and use the power of the battery box to supply power to the load bus.

[0076] Specifically, in combination Figure 3The system determines whether the power sag has ended. If the grid voltage stabilizes before the supercapacitor 3 runs out of energy, a system reset is performed. If the grid voltage remains abnormal and the SOC of the supercapacitor 3 drops to a preset low threshold (e.g., 30%), or if the remaining support time estimated based on the voltage drop depth and load power is insufficient (e.g., <1 second), it is determined to be a prolonged power sag and enters the energy storage emergency mode. The intelligent monitoring and control module 6 first controls the disconnection of the grid-connected switch 9 to isolate the load bus 7 from the faulty grid. It then starts the energy storage converter 4 and controls it to operate in voltage source inverter mode to establish a stable voltage and frequency for the load bus 7. Simultaneously, it can control the conduction of the bidirectional thyristor switch 8 to bypass the dynamic voltage restorer 2, reducing the power supply circuit impedance. At this point, all the power of the load is provided by the battery box 5 through the energy storage converter 4, achieving uninterrupted power supply for a long time.

[0077] S150. When the grid voltage is detected to have stabilized, the system reset operation is performed to switch to the normal grid power supply mode.

[0078] Specifically, in combination Figure 3 During emergency power supply from energy storage, the grid voltage status is continuously monitored. Once the grid voltage has fully stabilized and remained stable for a preset time, a system reset operation is performed. Specifically, this includes: First, controlling the energy storage converter 4 to switch to grid-connected mode, adjusting its output voltage amplitude, frequency, and phase to synchronize with the restored grid. Then, closing the grid-connected switch 9. Next, gradually reducing the output power (or current) of the energy storage converter 4, while the grid gradually increases its power output until the load power is fully supplied by the grid, and the output of the energy storage converter 4 drops to zero. This process achieves a seamless and smooth switching of the main power supply. After the switching is complete, controlling the energy storage converter 4 to switch to rectification mode, using grid power to charge the battery box 5, replenishing the energy consumed during emergency discharge. Finally, the system returns to the normal grid mode shown in step S110.

[0079] The control method for the anti-power fluctuation energy storage system provided in this embodiment of the invention is used to control the anti-power fluctuation energy storage system provided in any embodiment of the invention. Therefore, the control method for the anti-power fluctuation energy storage system provided in this embodiment of the invention also has the beneficial effects described in the above embodiments, and will not be repeated here.

[0080] Optionally, before entering the energy storage emergency mode, the connection between the load bus and the power grid may also be disconnected.

[0081] Specifically, disconnect the load bus from the power grid to prevent the energy storage converter from connecting to the faulty grid when the grid is abnormal, thus ensuring equipment safety.

[0082] Optionally, the system reset operation includes: After the energy storage converter is synchronized with the grid, the power supply to the load bus is switched back to the grid. The energy storage converter is controlled to charge the battery box to replenish the electrical energy consumed during emergency power supply.

[0083] Specifically, in combination Figure 3 First, the energy storage converter 4 is switched to grid-connected mode, and its output voltage amplitude, frequency, and phase are adjusted to synchronize with the restored power grid. Then, the grid-connected switch 9 is closed. Next, the output power (or current) of the energy storage converter 4 is gradually reduced, while the power output of the power grid gradually increases until the load power is fully supplied by the grid, and the output of the energy storage converter 4 drops to zero. This process achieves a seamless and smooth switching of the main power supply. After the switching is completed, the energy storage converter 4 is switched to rectification mode to use grid power to charge the battery box 5, replenishing the energy consumed in emergency discharge.

[0084] By establishing a full-process timing control logic that includes "voltage monitoring, bidirectional thyristor switch action, dynamic voltage restorer compensation, energy storage converter intervention, and grid reset", the action delay of each module is controlled at the millisecond level, ensuring that the load switches power sources without being aware of power fluctuations.

[0085] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An anti-power fluctuation energy storage system, characterized in that, include: A power grid access module is used to connect to an external power grid. A dynamic voltage restorer is connected between the power grid access module and the load bus to compensate the voltage of the load bus when the power grid voltage is abnormal. A supercapacitor, connected to the DC side of the dynamic voltage restorer, is used to provide short-term, rapid electrical support to the dynamic voltage restorer. An energy storage converter, the AC side of which is connected to the load bus via a switching device; The battery box is connected to the DC side of the energy storage converter and is used to store and release electrical energy; The intelligent monitoring and control module is connected to the grid access module, the dynamic voltage restorer, the supercapacitor, the energy storage converter, and the switching device, respectively. The intelligent monitoring and control module is used to control the dynamic voltage restorer and the supercapacitor to work together to compensate the voltage of the load bus when a short-term power dip is detected in the grid. The intelligent monitoring and control module is also used to control the energy storage converter to start and switch to inverter mode when the duration of the voltage fluctuation exceeds the support time of the supercapacitor or when the state of charge of the supercapacitor drops below a preset threshold, so as to convert the electrical energy of the battery box into AC power and output it to the load bus, so as to replace the dynamic voltage restorer and the supercapacitor to supply power to the load bus.

2. The anti-power fluctuation energy storage system according to claim 1, characterized in that, Also includes: A bidirectional thyristor switch is provided, which is connected between the dynamic voltage restorer and the load bus, and the intelligent monitoring and control module is connected to the bidirectional thyristor switch. The intelligent monitoring and control module is used to control the bidirectional thyristor switch to turn on when the power grid is normal, so that the dynamic voltage restorer is bypassed. The intelligent monitoring and control module is used to control the bidirectional thyristor switch to quickly turn off when a power dip is detected in the power grid, so as to enable the dynamic voltage restorer.

3. The anti-power fluctuation energy storage system according to claim 2, characterized in that, The intelligent monitoring and control module is also used to control the bidirectional thyristor switch to be turned on while the energy storage converter is supplying power to the load bus.

4. The anti-power fluctuation energy storage system according to claim 2, characterized in that, Also includes: Grid connection switch, wherein the grid connection switch is disposed between the grid access module and the energy storage converter; The intelligent monitoring and control module is connected to the grid-connected switch. Before controlling the energy storage converter to start emergency power supply, the intelligent monitoring and control module controls the grid-connected switch to disconnect, so as to isolate the load bus from the abnormal power grid.

5. The anti-power fluctuation energy storage system according to claim 4, characterized in that, The intelligent monitoring and control module is also used to control the energy storage converter to switch to grid-connected mode and synchronize with the grid after the grid voltage is detected to have returned to stability, control the grid-connected switch to close, control the energy storage converter to reduce the output power, switch the power supply of the load bus to be provided by the grid, and control the energy storage converter to switch to rectification mode to use the grid's electrical energy to charge the battery box.

6. The anti-power fluctuation energy storage system according to claim 1, characterized in that, During periods when the power grid is normal and there is a peak-valley electricity price difference, the intelligent monitoring and control module is also used to control the energy storage converter to charge the battery box during the off-peak electricity price period and to control the battery box to discharge through the energy storage converter during the peak electricity price period.

7. The anti-power fluctuation energy storage system according to claim 4, characterized in that, Also includes: First bypass switch and second bypass switch; The first bypass switch is connected in parallel with the grid-connected switch. The first bypass switch is used to close the grid-connected switch when it malfunctions or fails, ensuring that the grid-connected switch is out of service while the load bus is powered normally. The second bypass switch is connected in parallel with the bidirectional thyristor switch. The second bypass switch is used to close the circuit when the bidirectional thyristor switch malfunctions or fails, ensuring that the bidirectional thyristor switch stops operating while the load bus is powered normally.

8. A control method for an anti-power fluctuation energy storage system, applied to the anti-power fluctuation energy storage system according to any one of claims 1-7, characterized in that, The method includes: The intelligent monitoring and control module monitors the grid voltage status in real time. When a voltage dip or short-term interruption is detected in the power grid, it is determined to be a voltage drop, and a short-term compensation mode is entered. The dynamic voltage restorer is activated and the power of the supercapacitor is used to compensate the voltage of the load bus. The intelligent monitoring and control module continuously monitors the power sag and the support capacity of the supercapacitor. When a prolonged power slump is detected, the system switches to energy storage emergency mode, activates the inverter function of the energy storage converter, and uses the power of the battery box to supply power to the load bus. Once the grid voltage is detected to have stabilized, a system reset operation is performed, switching to the normal grid power supply mode.

9. The control method according to claim 8, characterized in that, Before entering the energy storage emergency mode, the process also includes disconnecting the load bus from the power grid.

10. The control method according to claim 8, characterized in that, The system reset operation includes: After synchronizing the energy storage converter with the power grid, the power supply to the load bus is switched back to the power grid. The energy storage converter is controlled to charge the battery box to replenish the electrical energy consumed during emergency power supply.

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