A grid-constructing energy storage and off-grid switching system

Abstract

The application discloses a network-constructing type energy storage parallel and off-grid switching system, which comprises a parallel and off-grid switching controller connected with an energy storage converter, an energy storage battery and a grid-connected switch. The parallel and off-grid switching controller is internally integrated with a double-side differential high-frequency power grid fault detection unit, which synchronously and parallelly collects double-side electrical parameters in a pure hardware mode, filters 2.1MW working condition electromagnetic interference through a hardware differential logic, judges the abnormality according to four types of criteria, i.e., voltage sudden rise, voltage sudden drop, frequency over upper limit and frequency over lower limit, and hardware anti-shake, and outputs a hardware fault mark; a multi-stage interlocking mode switching time sequence state machine composed of a pure hardware logic gate array receives the fault mark or manual instruction, makes the fault emergency switching channel prior to the planned manual switching according to a solidified priority, controls the bidirectional smooth switching of the converter between the current source mode and the voltage source mode and the grid-connected switch opening and closing time sequence, and realizes the full working condition switching of the grid connection, planned off-grid and emergency off-grid under the 2.1MW level.

Description

Technical Field

[0001] This invention relates to the field of energy storage power electronic control technology, specifically to a grid-connected energy storage and off-grid switching system. Background Technology

[0002] Grid-based energy storage systems rely on energy storage converters to autonomously establish and maintain stable voltage and frequency, enabling flexible switching between grid-connected and off-grid operation. They are widely used in microgrids, uninterrupted power supply for critical loads, and grid-connected support for new energy sources. With the continuous promotion of high-power energy storage projects of 2MW and above, the market has raised higher standards for the smoothness, reliability, and response speed of grid-connected and off-grid switching.

[0003] Currently, the industry commonly employs three types of conventional solutions for grid-connected and off-grid switching. One type uses a fully software architecture, relying on the main control chip and embedded programs to complete parameter sampling, operating condition judgment, switching operations, and converter mode switching. Another type adds a simple hardware protection circuit outside the software system, which can output protection signals for voltage and frequency anomalies, but the linkage and coordination between the software and hardware are insufficient. The third type combines a switching switch with conventional synchronizing equipment, relying on an independent relay to complete grid-connected synchronization judgment, while off-grid control is implemented separately by other equipment.

[0004] The existing solutions described above reveal numerous shortcomings under high-power conditions. Most core system control components rely on software implementation; issues such as program malfunctions and response delays can easily disrupt switching timing, leading to mismatches in equipment operating states and posing safety risks. Electromagnetic interference generated by high-power equipment can easily affect sampling signals, and traditional software filtering methods are slow to respond, making it difficult to ensure timely fault handling. Furthermore, conventional synchronization determination mechanisms lack emergency response capabilities and cannot automatically return to a safe state in the event of synchronization anomalies; voltage jumps are prone to occur during grid-connected to off-grid transitions, potentially triggering load or protection device malfunctions. In addition, relying solely on auxiliary switch contacts to determine position status is insufficient to address issues such as contact welding and mechanical jamming, resulting in inaccurate status determination; traditional timed waveform recording modes generate a large amount of redundant data, wasting storage resources and easily causing the loss of critical transient data during switching. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a grid-connected energy storage and off-grid switching system, which solves the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] It includes a 2.1MW rated power energy storage converter, energy storage battery, and grid connection switch, and also includes:

[0008] A grid-connected / off-grid switching controller, which is electrically connected to an energy storage converter, a grid-connected switch, a grid-side voltage detection point, and a load-side voltage detection point, respectively.

[0009] The grid-connected / off-grid switching controller integrates:

[0010] The dual-side differential high-frequency power grid fault detection unit is used to synchronously and parallelly collect electrical parameters on both the power grid side and the load side in a purely hardware manner. It filters out electromagnetic interference noise under the 2.1MW high-power condition through hardware differential logic. Based on four criteria—voltage surge, voltage drop, frequency exceeding the upper limit, and frequency exceeding the lower limit—and combined with hardware anti-jitter logic, it determines whether the electrical parameters are abnormal and outputs a hardware fault flag signal.

[0011] A multi-level interlocked mode switching timing state machine composed of a pure hardware logic gate array is used to receive fault flag signals or external manual switching commands, and to distinguish between state jumps and priorities according to the pure hardware-fixed state jump logic. The emergency switching channel has a higher priority than the planned manual switching channel. It controls the bidirectional smooth switching of the energy storage converter between current source and voltage source modes and the opening or closing sequence of the grid-connected switch, thereby performing full-condition switching of grid connection, planned off-grid and emergency off-grid at the 2.1MW power level.

[0012] Furthermore, the on-grid and off-grid switching controller also integrates a synchronous pre-synchronization closed-loop fault-tolerant module, which is composed of a hardware-level synchronous pre-synchronization closed-loop verification unit and a pre-synchronization failure closed-loop fault-tolerant unit cascaded together.

[0013] The synchronous pre-synchronization closed-loop verification unit is used to compare the amplitude, phase and frequency of the output voltage of the energy storage converter with the voltage on the grid side in real time, and outputs a synchronous allow-closing flag signal when all three deviations fall within the preset threshold.

[0014] The pre-synchronization failure closed-loop fault-tolerant unit is used to monitor the synchronization comparison results. If the synchronization access threshold cannot be met within the preset timeout period, the closing command of the grid-connected switch will be terminated immediately, the hardware will be blocked, and the energy storage converter will be forced to switch back to the steady-state current source grid-connected mode before the switchover. At the same time, a dual alarm signal of passive hard contact and remote communication message will be output.

[0015] Furthermore, the on-grid and off-grid switching controller also integrates an off-grid seamless support module, which is composed of a high-power adaptive off-grid voltage adaptive locking unit and a front-end non-delay load power prediction unit.

[0016] The off-grid voltage adaptive locking unit is used to collect the grid-side voltage of the last complete power frequency cycle before the off-grid switching is triggered and calculate the average value to obtain the steady-state reference voltage. When the energy storage converter enters the off-grid independent operation state and there is no grid voltage reference signal, the dynamic reference voltage is locked as the output reference value throughout the off-grid process to eliminate the voltage step deviation during the grid-to-off-grid transition.

[0017] The load power prediction unit is used to perform load power prediction in parallel after receiving the off-grid command and before the switching is executed. When the total load power is detected to exceed 80% of the rated off-grid capacity of the energy storage converter, a hardware interlock signal is generated to lock the off-grid switching action, and an overload warning signal is output synchronously.

[0018] Furthermore, the on-grid / off-grid switching controller also integrates a hardware redundancy verification module for switch status, including two independent hardware verification links: a first verification unit and a second verification unit.

[0019] The first verification unit adopts a dual verification logic of switch auxiliary contact feedback and grid load double-sided voltage difference detection. The switch is determined to be reliably closed only when the auxiliary contact feedback is effective and the double-sided voltage difference is continuously less than 5% of the rated voltage.

[0020] The second verification unit cross-compares the switch control command issued by the controller with the actual state of the switch. When the results of the two verification links simultaneously meet the preset criteria, the module outputs a valid switch state flag; if any one verification is abnormal, the hardware protection interlocking logic is immediately triggered.

[0021] Furthermore, the grid-connected switch adopts an integrated structure of a double-break vacuum contactor adapted to 2.1MW high-power conditions and a mechanical anti-jamming linkage mechanism.

[0022] The dual-break vacuum contactor has a first break and a second break arranged in series. The two breaks are synchronously driven by the same electromagnetic operating mechanism through a rigid connecting rod, and a voltage equalization capacitor assembly is provided between the first break and the second break to equalize the break voltage.

[0023] The mechanical anti-jamming linkage mechanism includes:

[0024] A guide shaft passes through the center of the moving iron core of the electromagnetic operating mechanism. Buffer springs are provided at both ends of the guide shaft to absorb the impact kinetic energy at the end of opening and closing and to prevent the moving iron core from wearing out and getting stuck.

[0025] The auxiliary contact linkage arm is fixedly connected to the rigid connecting rod as a whole. Its end directly drives the auxiliary contact group, eliminating the timing deviation between the auxiliary contact and the main contact.

[0026] Bistable holding permanent magnets are set on both sides of the electromagnetic operating mechanism to provide holding force in the closed and open positions, reduce coil holding current and prevent false opening caused by abnormal vibration;

[0027] The voltage equalization capacitor assembly is configured with an independent voltage sampling node, which is used to synchronously feed back the voltage equalization information of the break point to the hardware redundancy verification module of the switch state.

[0028] Furthermore, the on-grid / off-grid switching controller adopts a heterogeneous solidified collaborative hardware architecture of DSP+FPGA;

[0029] Among them, the DSP core is dedicated to performing high-precision floating-point operations, which are used to complete grid voltage synchronization calculation, mode switching timing calculation and closed-loop current control algorithm.

[0030] The FPGA core is dedicated to performing nanosecond-level high-speed hardware signal processing, and is a pure hardware logic gate array that implements high-speed IO acquisition, hardware verification of switch status, waveform recording triggered by switching transient events, optical fiber communication timing analysis, and the multi-level interlock mode switching timing state machine.

[0031] Data exchange between the DSP and FPGA is achieved through a hardware-level dual-port RAM.

[0032] Furthermore, the grid-connected and off-grid switching controller also integrates a switching transient event triggering waveform recording unit. The waveform recording unit is implemented using FPGA hardware resources. The triggering end of the switching transient event triggering waveform recording unit is electrically connected to the state output end of the multi-level interlocking mode switching timing state machine. The storage end of the switching transient event triggering waveform recording unit is electrically connected to the local non-volatile memory.

[0033] The switching transient event triggering waveform recording unit is used to respond only to real events such as grid-connected switching, off-grid switching command issuance, and actual operation of grid-connected switches. It collects full-condition operating data within two complete power frequency cycles before and after the switching action, adds hardware timestamps, and then encrypts and stores the data. This abandons the traditional fixed-cycle timed waveform recording mode and eliminates redundant invalid waveform recording data under steady-state operating conditions.

[0034] Furthermore, the system also includes dual-channel high-speed fiber optic communication links, which are bidirectionally connected to the grid-connected / off-grid switching controller and the energy storage converter, respectively, for complete electrical isolation.

[0035] The on-grid and off-grid switching controller also integrates an optical fiber communication hardware acceleration module, which is composed of a dual-channel optical fiber communication protocol hardware parsing unit and a dual-channel optical fiber communication link redundancy switching unit cascaded together.

[0036] The protocol hardware parsing unit is dedicated to parsing communication data with fixed frame length and fixed interval. The single communication cycle is no more than 100 microseconds, and there are no network congestion or data packet loss problems.

[0037] The link redundancy switching unit is used to automatically and seamlessly switch to the backup channel in nanoseconds in a hardware manner when the main channel experiences a communication interruption.

[0038] Furthermore, the system also includes:

[0039] A system status output module is provided, wherein the input terminal of the system status output module is electrically connected to the status output terminal and the communication output terminal of the grid-connected switching controller, and the system status output module is used to output the operating status, fault type and switching waveform data of the grid-connected switching controller to the local display terminal and the remote monitoring backend, respectively.

[0040] Furthermore, the system status output module includes a local status display and early warning terminal and a remote monitoring and communication gateway;

[0041] The local status display and early warning terminal is used to display and monitor the operating status, fault type and switching waveform data of the off-grid switching controller in real time, and to trigger a local audible and visual alarm when the system is abnormal.

[0042] The remote monitoring communication gateway is used to convert the operating status, fault alarm signals and switching waveform data of the on-grid and off-grid switching controller into standard remote communication messages and upload them to the remote monitoring backend.

[0043] This invention provides a grid-connected energy storage and off-grid switching system. Compared with existing technologies, it has the following advantages:

[0044] 1. This invention employs a pure hardware logic gate array to implement a state machine for grid fault detection and multi-level interlocking switching. It solidifies and executes all core functions, including fault identification, state transitions, switching timing control, and converter mode switching, in hardware, avoiding the timing disorder and operating condition mismatch problems caused by program anomalies, interruptions, delays, and computational congestion in traditional software control architectures. Simultaneously, the hardware-solidified priority logic for fault switching ensures independent operation of the dual channels without interference, guaranteeing the stability and safety of the 2.1MW high-power energy storage system across all operating conditions, including grid connection, planned off-grid operation, and emergency fault disconnection.

[0045] 2. This invention relies on dual-sided differential hardware detection combined with hardware anti-jitter logic to accurately filter out electromagnetic interference noise generated by the switching operation of high-power converters. It eliminates software algorithm delays and effectively prevents fault misjudgment and switching malfunctions caused by interference. Simultaneously, it is equipped with a hardware-level grid-connected pre-synchronization fault-tolerance mechanism. In response to grid-connected synchronization timeouts and parameter mismatch anomalies, it can automatically lock the closing circuit, switch back to a safe operating condition, and trigger dual alarms. This solves the shortcomings of traditional solutions such as synchronization anomaly suspension and lack of emergency fault tolerance, and is suitable for the unattended operation requirements of high-power energy storage stations.

[0046] 3. This invention utilizes an off-grid voltage adaptive locking mechanism to replicate the average steady-state power frequency voltage of the grid-connected system as the off-grid voltage base, completely eliminating voltage jumps during the grid-to-off-grid transition and preventing maloperation of sensitive loads and false triggering of protection systems. Simultaneously, it incorporates pre-configured hardware load power prediction logic to identify overload conditions and hardware-lock the switch before off-grid switching, mitigating the risk of high-power off-grid overload shutdowns and voltage collapses from the source, ensuring the continuity and smoothness of power supply to large-capacity loads.

[0047] 4. This invention employs a dual hardware verification link consisting of switch contact feedback, dual-sided differential pressure detection, and cross-comparison of commands and status. This accurately identifies anomalies such as switch malfunctions (false closing, false opening, contact welding, mechanical jamming, etc.) under high-power conditions, preventing equipment failures caused by misjudgments of status. Combined with a DSP+FPGA heterogeneous hardware architecture, dual-channel high-speed redundant fiber optic communication, and an event-triggered hardware waveform recording mechanism, it ensures high-speed, low-latency, and anti-interference operation of the system while eliminating invalid data redundancy. It can accurately trace the source of transient switching processes. Combined with local and remote status output and alarm functions, it significantly improves the fault handling capabilities and maintenance convenience of high-power energy storage switching systems. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A connection block diagram of a grid-connected energy storage and off-grid switching system according to the present invention is shown. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] like Figure 1 As shown, this invention discloses a grid-type energy storage on-grid and off-grid switching system, which is adapted to the operation of 2.1MW high-power energy storage. The overall system includes: energy storage converter, energy storage battery, grid-connected switch, on-grid and off-grid switching controller, dual-channel high-speed optical fiber communication link and system status output module.

[0052] To facilitate understanding of the overall working logic of this invention, the overall system workflow is first described: The system operates normally in two steady-state modes: grid-connected operation and off-grid independent operation. It can realize three switching scenarios: planned grid connection, planned off-grid operation, and emergency off-grid operation due to grid faults. In grid-connected mode, the energy storage converter operates in current source mode, generating electricity synchronously with the grid voltage. In off-grid mode, the energy storage converter switches to voltage source mode, autonomously establishing and maintaining the load-side voltage frequency. All switching sequences, fault determinations, and status verifications are executed by the grid-connected / off-grid switching controller hardware logic, achieving seamless and highly reliable switching across all operating conditions.

[0053] This energy storage converter has a rated power of 2.1MW and supports both current source grid-connected operation and voltage source off-grid independent operation modes. It can smoothly switch between these two modes under the command of the grid-connected / off-grid switching controller. Its DC side is connected to the energy storage battery, and its AC side is connected to the grid and load via a grid-connected switch. The 2.1MW power level corresponds to the typical requirements of medium-sized industrial and commercial energy storage or microgrid backbone power supply. At this power level, the electromagnetic interference generated by the converter's switching devices is significantly higher than that of low-power equipment, placing higher demands on the anti-interference capability of the control system.

[0054] Energy storage batteries, acting as DC energy storage elements, provide DC power to the energy storage converter or absorb feedback power from the converter. The battery type can be lithium iron phosphate batteries or other suitable high-capacity energy storage batteries, with rated voltage and capacity matched to the 2.1MW converter to ensure sufficient energy output during off-grid support.

[0055] The grid-connected switch connects the AC output of the energy storage converter to the power grid and common load points, providing physical isolation between grid-connected and off-grid states. This switch must have a switching capacity of 2.1MW. This system employs an integrated structure combining a high-power dual-break vacuum contactor with a mechanical anti-jamming linkage mechanism. Its opening and closing are directly controlled by the grid-connected / off-grid switching controller, which simultaneously feeds back auxiliary contact and break voltage equalization information to the switch status hardware redundancy verification module.

[0056] A grid-connected / off-grid switching controller, which is electrically connected to an energy storage converter, a grid-connected switch, a grid-side voltage detection point, and a load-side voltage detection point, respectively; the grid-connected / off-grid switching controller integrates:

[0057] The dual-sided differential high-frequency grid fault detection unit is used to synchronously and parallelly acquire electrical parameters from both the grid and load sides in a purely hardware-based manner. It filters out electromagnetic interference noise under 2.1MW high-power conditions through hardware differential logic. Based on four criteria—voltage surge, voltage sag, frequency exceeding the upper limit, and frequency exceeding the lower limit—and combined with hardware anti-jitter logic, it determines whether electrical parameters are abnormal and outputs a hardware fault flag signal. This dual-sided differential high-frequency grid fault detection unit is implemented entirely in hardware, without analog-to-digital conversion or software algorithm filtering. In the strong electromagnetic interference environment generated by the switching action of high-power converters, the hardware differential logic can cancel common-mode interference within nanoseconds, preserving differential-mode fault characteristics. Compared to software filtering, which may introduce tens of millisecond delays, this unit can output fault flags within microseconds, ensuring that the grid-connected / off-grid switching controller responds promptly to grid anomalies. In this embodiment, for example, the fault criterion adopts the preferred threshold for an industry-adapted 2.1MW energy storage system: the voltage surge threshold is 110% of the rated voltage, the voltage drop threshold is 90% of the rated voltage, the frequency over-limit threshold is 49Hz~51Hz, and the hardware anti-shake duration is fixed at 2ms, which can effectively avoid false triggering due to instantaneous interference.

[0058] A multi-level interlocked mode switching timing state machine, composed of a pure hardware logic gate array, receives fault flag signals or external manual switching commands. It operates according to a purely hardware-based, fixed state transition and priority distinction logic, with the emergency switching channel having higher priority than the planned manual switching channel. This controls the bidirectional smooth switching of the energy storage converter between current source and voltage source modes, as well as the opening and closing sequence of the grid-connected switch, enabling full-condition switching of grid connection, planned off-grid operation, and emergency off-grid operation at a power level of 2.1MW. This state machine is entirely implemented using hardware logic gates and does not rely on any software programs. The multi-level interlocking design ensures that only one switching process is active at any given time, preventing mismatches between converter mode and switch state due to software errors or interruptions. The fixed priority logic ensures that emergency off-grid operation triggered by grid faults always takes precedence over planned manual switching, automatically preempting control without software judgment, making it suitable for high-power energy storage systems with stringent switching safety requirements.

[0059] The on-grid and off-grid switching controller also integrates a synchronous pre-synchronization closed-loop fault-tolerant module, which is composed of a hardware-level synchronous pre-synchronization closed-loop verification unit and a pre-synchronization failure closed-loop fault-tolerant unit cascaded together.

[0060] The synchronous pre-synchronization closed-loop verification unit is used to compare the amplitude, phase and frequency of the output voltage of the energy storage converter with the voltage on the grid side in real time, and outputs a synchronous allow-closing flag signal when all three deviations fall within the preset threshold.

[0061] The pre-synchronization failure closed-loop fault-tolerant unit is used to monitor the synchronization comparison results. If the synchronization threshold cannot be met within the preset timeout period, the closing command of the grid-connected switch is immediately terminated, the hardware is blocked, and the energy storage converter is forcibly switched back to the steady-state current source grid-connected mode before the switchover. At the same time, a dual alarm signal of passive hard contact and remote communication message is output. In the above cascaded structure, the first stage continuously performs synchronization verification, and the second stage independently monitors the verification result. If the synchronization condition cannot be met for a long time due to sampling interference or grid fluctuations, the existing technology often waits continuously or simply alarms after a timeout, leaving the system in an uncertain state. This module restores the converter to the safe operating mode before the switchover through hardware blocking and forced switching back, avoiding long-term floating. The passive hard contact signal can be directly connected to the protection circuit, and the remote communication message is recorded by the background. The dual alarm ensures the maintainability of unattended sites. For example, the preferred synchronization threshold in this embodiment is: voltage amplitude deviation ≤3%, frequency deviation ≤0.1Hz, phase deviation ≤3°, and the synchronization timeout judgment time is set to 5s.

[0062] The on-grid and off-grid switching controller also integrates an off-grid seamless support module, which is composed of a high-power adaptive off-grid voltage adaptive locking unit and a front-end no-delay load power prediction unit.

[0063] The off-grid voltage adaptive locking unit is used to collect the grid-side voltage of the last complete power frequency cycle before the off-grid switching is triggered and calculate the average value to obtain the steady-state reference voltage. When the energy storage converter enters the off-grid independent operation state and there is no grid voltage reference signal, this dynamic reference voltage is locked as the output reference value throughout the off-grid process, eliminating voltage step deviation during the grid-to-off-grid transition. In traditional schemes, at the moment of grid-to-off-grid transition, the converter switches from a current source mode that tracks the grid voltage to a voltage source mode that builds up voltage autonomously, which may cause voltage surges due to the loss of the grid reference value. This unit locks the average grid voltage of the last power frequency cycle before the switching in advance, and directly uses this as the output reference after off-grid transition, ensuring the continuity of voltage amplitude before and after the switching and avoiding malfunctions of sensitive loads due to voltage jumps.

[0064] The load power prediction unit is used to perform load power prediction in parallel after receiving the off-grid command and before the switching is executed. When the total load power is detected to exceed 80% of the rated off-grid capacity of the energy storage converter, a hardware interlock signal is generated to lock the off-grid switching action, and an overload warning signal is output simultaneously. This prediction unit completes load power detection before the switching is executed. If the total load power has exceeded 80% of the rated off-grid capacity of the converter, it means that the converter will operate close to full load or even overload after off-grid, posing a risk of protection shutdown. The hardware interlock signal locks the off-grid action within nanoseconds to avoid off-grid failure due to overload after the switching, and at the same time outputs a warning signal to prompt maintenance personnel to disconnect part of the load first to ensure that the off-grid switching is successful on the first attempt.

[0065] The on-grid / off-grid switching controller also integrates a hardware redundancy verification module for switch status, including two independent hardware verification links: a first verification unit and a second verification unit. For example, in this embodiment, the voltage difference threshold corresponding to the 380V system is continuously less than 19V.

[0066] The first verification unit adopts a dual verification logic of switch auxiliary contact feedback and grid load double-sided voltage difference detection. The switch is determined to be reliably closed only when the auxiliary contact feedback is effective and the double-sided voltage difference is continuously less than 5% of the rated voltage.

[0067] The second verification unit cross-compares the switch control commands issued by the controller with the actual switch status. When both verification results simultaneously meet the preset criteria, the module outputs a valid switch status flag; if either verification fails, the hardware protection interlocking logic is immediately triggered. Under high-power conditions, the main contacts of the grid-connected switch may be in a false closed position due to arc welding or mechanical jamming, but the auxiliary contacts may still report normal operation. This fault cannot be identified solely by the auxiliary contacts. This module adds dual-sided differential voltage detection to the first channel: if the switch is truly closed, the voltage on the grid side and the load side should be approximately equal; if the auxiliary contacts report closing but the differential voltage is greater than 5%, it indicates that the main contacts are not reliably connected. The second channel cross-compares the control commands with the actual status; for example, if the command is to open but the status remains closed, an anomaly is determined. The switch status is only considered valid if both independent hardware verifications are met simultaneously; any anomaly immediately blocks subsequent switching to prevent misoperation.

[0068] The grid-connected switch adopts an integrated structure of a double-break vacuum contactor and a mechanical anti-jamming linkage mechanism adapted to 2.1MW high-power conditions.

[0069] The dual-break vacuum contactor has a first break and a second break arranged in series. The two breaks are synchronously driven by the same electromagnetic operating mechanism through a rigid connecting rod, and a voltage equalization capacitor assembly is provided between the first break and the second break to equalize the break voltage.

[0070] The mechanical anti-jamming linkage mechanism includes:

[0071] Specifically, the guide shaft passes through the center of the moving iron core of the electromagnetic operating mechanism, and buffer springs are provided at both ends of the guide shaft to absorb the impact kinetic energy at the end of opening and closing and to prevent the moving iron core from being worn and stuck.

[0072] Specifically, the auxiliary contact linkage arm is fixedly connected to the rigid linkage, and its end directly drives the auxiliary contact group to eliminate the timing deviation between the auxiliary contact and the main contact.

[0073] Specifically, bistable holding permanent magnets are set on both sides of the electromagnetic operating mechanism to provide holding force in the closed and open positions, reduce coil holding current and prevent false opening caused by abnormal vibration.

[0074] The voltage equalizing capacitor assembly is equipped with an independent voltage sampling node to synchronously feed back the voltage equalization information of the break points to the hardware redundancy verification module for the switch status. For high-power applications like 2.1MW, a single break point is difficult to reliably disconnect; a series dual-break configuration can share the voltage. The voltage equalizing capacitor assembly ensures uniform voltage distribution between the two breaks, preventing uneven voltage distribution from causing reignition on a single break point. The same electromagnetic operating mechanism synchronously drives the two breaks through a rigid connecting rod, ensuring consistent action. The guide shaft and buffer spring prevent wear and jamming of the moving iron core after long-term operation, extending mechanical life. The auxiliary contact linkage arm is fixed to the rigid connecting rod, ensuring strict synchronization between the auxiliary contact and the main contact, avoiding status feedback errors due to timing deviations. A bistable permanent magnet provides holding force in both the closed and open positions; the coil is energized only during switching, reducing heat generation and energy consumption, while also preventing false tripping caused by vibration. The independent voltage sampling node feeds back the voltage equalization signal of the break points to the hardware redundancy verification module for the switch status, allowing the switch's own electrical state to participate in status verification, further improving reliability.

[0075] The on-grid and off-grid switching controller adopts a heterogeneous solidified collaborative hardware architecture of DSP (high-precision computing core) + FPGA (pure hardware high-speed processing core).

[0076] Among them, the DSP core is dedicated to performing high-precision floating-point operations, which are used to complete grid voltage synchronization calculation, mode switching timing calculation and closed-loop current control algorithm.

[0077] The FPGA core is dedicated to performing nanosecond-level high-speed hardware signal processing, and is a pure hardware logic gate array that implements high-speed IO acquisition, hardware verification of switch status, waveform recording triggered by switching transient events, optical fiber communication timing analysis, and the multi-level interlock mode switching timing state machine.

[0078] The DSP and FPGA exchange data via a hardware-level dual-port RAM. In traditional single-processor architectures, floating-point operations and high-speed signal processing compete for CPU resources, leading to a decrease in real-time performance. This architecture allocates two types of tasks to different hardware cores: the DSP excels at complex algorithm calculations, handling voltage synchronization, mode switching time calculations, and current regulation control; the FPGA performs pure hardware parallel processing of I / O acquisition, status verification, waveform recording triggering, and communication timing analysis, with a response latency in the nanosecond range. Both share data through the dual-port RAM without blocking each other, ensuring both the accuracy of the control algorithm and the high-speed response of fault detection and state machines. This is particularly suitable for high-power energy storage systems that require both real-time performance and computational power.

[0079] The on-grid / off-grid switching controller also integrates a switching transient event triggering waveform recording unit. The waveform recording unit is implemented using FPGA hardware resources. The triggering end of the switching transient event triggering waveform recording unit is electrically connected to the state output end of the multi-level interlocking mode switching timing state machine. The storage end of the switching transient event triggering waveform recording unit is electrically connected to the local non-volatile memory.

[0080] The transient event-triggered waveform recording unit is used only in response to real events such as grid-connected switching, off-grid switching command issuance, and actual operation of the grid-connected switch. It collects full-condition operating data for two complete power frequency cycles before and after the switching action, adds hardware timestamps, and encrypts and stores the data. This abandons the traditional fixed-period timed waveform recording mode and eliminates redundant invalid waveform recording data under steady-state conditions. Traditional power electronic devices often use fixed-period timed waveform recording (e.g., recording data every millisecond). During the long-term continuous operation of the 2.1MW energy storage system, massive amounts of steady-state data are generated, occupying storage space, and critical data may be overwritten when a switching event actually occurs. This unit is directly triggered by the state machine, starting waveform recording only when the switching action occurs. It captures data for two power frequency cycles (80ms in total, calculated at 50Hz) before and after the switching action, adds hardware timestamps, and encrypts and stores the data. This approach concentrates storage resources on the transient process, avoiding redundant invalid data while ensuring the integrity and security of critical data.

[0081] Specifically, a dual-channel high-speed fiber optic communication link is bidirectionally connected to the grid-connected / off-grid switching controller and the energy storage converter, respectively, for complete electrical isolation;

[0082] The on-grid and off-grid switching controller also integrates an optical fiber communication hardware acceleration module, which is composed of a dual-channel optical fiber communication protocol hardware parsing unit and a dual-channel optical fiber communication link redundancy switching unit cascaded together.

[0083] The protocol hardware parsing unit is dedicated to parsing communication data with fixed frame length and fixed interval. The single communication cycle is no more than 100 microseconds, and there are no network congestion or data packet loss problems.

[0084] The link redundancy switching unit is used to automatically and seamlessly switch to the backup channel within nanoseconds in the event of a communication interruption in the main channel. Near high-power converters, electrical noise is severe, and traditional metal cable communication is easily interfered with. The fiber optic link achieves complete electrical isolation between the controller and the converter, blocking ground potential differences and electromagnetic coupling paths. The communication protocol uses a fixed frame length and fixed interval; the hardware parsing unit does not require software protocol stack processing, and a single communication cycle does not exceed 100 microseconds, ensuring the real-time performance of control commands and status feedback. Dual-channel redundancy design: when the main channel is normal, data is transmitted through the main channel; once the main channel is interrupted (fiber optic cable breakage or transceiver failure), the link redundancy switching unit automatically switches to the backup channel within nanoseconds, ensuring uninterrupted communication. The switching process is completely transparent to upper-layer control, avoiding failure of on / offline switching due to communication interruption.

[0085] Specifically, a system status output module is provided. The input terminal of the system status output module is electrically connected to the status output terminal and the communication output terminal of the grid-connected switching controller. The system status output module is used to output the operating status, fault type and switching waveform data of the grid-connected switching controller to the local display terminal and the remote monitoring backend, respectively.

[0086] The system status output module includes a local status display and early warning terminal and a remote monitoring and communication gateway.

[0087] The local status display and early warning terminal is used to display and monitor the operating status, fault type and switching waveform data of the off-grid switching controller in real time, and to trigger a local audible and visual alarm when the system is abnormal.

[0088] The remote monitoring communication gateway is used to convert the operating status, fault alarm signals, and switching waveform data of the on-grid / off-grid switching controller into standard remote communication messages and upload them to the remote monitoring backend. This system provides both local and remote monitoring modes. On-site maintenance personnel can directly view the current operating status, fault type, and waveform data of the most recent switching through the local display terminal; audible and visual alarms facilitate rapid location of anomalies. The remote monitoring communication gateway encapsulates the data into standard communication messages (such as Modbus TCP, IEC 61850, etc.) and uploads them to the dispatch center or cloud platform for remote centralized monitoring. These two modes operate in parallel, improving system observability and maintenance convenience.

[0089] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0090] In the embodiments provided herein, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the couplings or direct couplings or communication connections shown or discussed may be indirect couplings or communication connections through some interfaces, apparatuses, or units, or they may be electrical, mechanical, or other forms of connection.

[0091] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments described herein, depending on actual needs.

[0092] Furthermore, the functional units in the various embodiments of this document can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0093] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this paper, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this paper. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.

[0094] This document uses specific embodiments to illustrate the principles and implementation methods of this document. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this document. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this document. Therefore, the content of this specification should not be construed as a limitation of this document.

Claims

1. A grid-connected energy storage system for switching between grid and off-grid operation, comprising an energy storage converter with a rated power of 2.1MW, an energy storage battery, and a grid-connected switch, characterized in that, Also includes: A grid-connected / off-grid switching controller, which is electrically connected to an energy storage converter, a grid-connected switch, a grid-side voltage detection point, and a load-side voltage detection point, respectively. The grid-connected / off-grid switching controller integrates: The dual-side differential high-frequency power grid fault detection unit is used to synchronously and parallelly collect electrical parameters on both the power grid side and the load side in a purely hardware manner. It filters out electromagnetic interference noise under the 2.1MW high-power condition through hardware differential logic. Based on four criteria—voltage surge, voltage drop, frequency exceeding the upper limit, and frequency exceeding the lower limit—and combined with hardware anti-jitter logic, it determines whether the electrical parameters are abnormal and outputs a hardware fault flag signal. A multi-level interlocked mode switching timing state machine composed of a pure hardware logic gate array is used to receive fault flag signals or external manual switching commands, and to distinguish between state jumps and priorities according to the pure hardware-fixed state jump logic. The emergency switching channel has a higher priority than the planned manual switching channel. It controls the bidirectional smooth switching of the energy storage converter between current source and voltage source modes and the opening or closing sequence of the grid-connected switch, thereby performing full-condition switching of grid connection, planned off-grid and emergency off-grid at the 2.1MW power level.

2. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The on-grid and off-grid switching controller also integrates a synchronous pre-synchronization closed-loop fault-tolerant module, which is composed of a hardware-level synchronous pre-synchronization closed-loop verification unit and a pre-synchronization failure closed-loop fault-tolerant unit cascaded together. The synchronous pre-synchronization closed-loop verification unit is used to compare the amplitude, phase and frequency of the output voltage of the energy storage converter with the voltage on the grid side in real time, and outputs a synchronous allow-closing flag signal when all three deviations fall within the preset threshold. The pre-synchronization failure closed-loop fault-tolerant unit is used to monitor the synchronization comparison results. If the synchronization access threshold cannot be met within the preset timeout period, the closing command of the grid-connected switch will be terminated immediately, the hardware will be blocked, and the energy storage converter will be forced to switch back to the steady-state current source grid-connected mode before the switchover. At the same time, a dual alarm signal of passive hard contact and remote communication message will be output.

3. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The on-grid and off-grid switching controller also integrates an off-grid seamless support module, which is composed of a high-power adaptive off-grid voltage adaptive locking unit and a front-end no-delay load power prediction unit. The off-grid voltage adaptive locking unit is used to collect the grid-side voltage of the last complete power frequency cycle before the off-grid switching is triggered and calculate the average value to obtain the steady-state reference voltage. When the energy storage converter enters the off-grid independent operation state and there is no grid voltage reference signal, the dynamic reference voltage is locked as the output reference value throughout the off-grid process to eliminate voltage step deviation during the grid-to-off-grid transition. The load power prediction unit is used to perform load power prediction in parallel after receiving the off-grid command and before the switching is executed. When the total load power is detected to exceed 80% of the rated off-grid capacity of the energy storage converter, a hardware interlock signal is generated to lock the off-grid switching action, and an overload warning signal is output synchronously.

4. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The on-grid and off-grid switching controller also integrates a hardware redundancy verification module for switch status, including two independent hardware verification links: a first verification unit and a second verification unit. The first verification unit adopts a dual verification logic of switch auxiliary contact feedback and grid load double-sided voltage difference detection. The switch is determined to be reliably closed only when the auxiliary contact feedback is effective and the double-sided voltage difference is continuously less than 5% of the rated voltage. The second verification unit cross-compares the switch control command issued by the controller with the actual state of the switch. When the results of the two verification links simultaneously meet the preset criteria, the module outputs a valid switch state flag. If any verification fails, the hardware protection interlocking logic will be triggered immediately.

5. The grid-connected energy storage and off-grid switching system according to claim 4, characterized in that, The grid-connected switch adopts an integrated structure of a double-break vacuum contactor and a mechanical anti-jamming linkage mechanism adapted to 2.1MW high-power conditions. The dual-break vacuum contactor has a first break and a second break arranged in series. The two breaks are synchronously driven by the same electromagnetic operating mechanism through a rigid connecting rod, and a voltage equalization capacitor assembly is provided between the first break and the second break. Used to balance the voltage at the break point; The mechanical anti-jamming linkage mechanism includes: A guide shaft passes through the center of the moving iron core of the electromagnetic operating mechanism. Buffer springs are provided at both ends of the guide shaft to absorb the impact kinetic energy at the end of opening and closing and to prevent the moving iron core from wearing out and getting stuck. The auxiliary contact linkage arm is fixedly connected to the rigid connecting rod as a whole. Its end directly drives the auxiliary contact group, eliminating the timing deviation between the auxiliary contact and the main contact. Bistable holding permanent magnets are set on both sides of the electromagnetic operating mechanism to provide holding force in the closed and open positions, reduce coil holding current and prevent false opening caused by abnormal vibration; The voltage equalization capacitor assembly is configured with an independent voltage sampling node, which is used to synchronously feed back the voltage equalization information of the break point to the hardware redundancy verification module of the switch state.

6. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The on-grid / off-grid switching controller adopts a heterogeneous solidified collaborative hardware architecture of DSP+FPGA; Among them, the DSP core is dedicated to performing high-precision floating-point operations, which are used to complete grid voltage synchronization calculation, mode switching timing calculation and closed-loop current control algorithm. The FPGA core is dedicated to performing nanosecond-level high-speed hardware signal processing, and is a pure hardware logic gate array that implements high-speed IO acquisition, hardware verification of switch status, waveform recording triggered by switching transient events, optical fiber communication timing analysis, and the multi-level interlock mode switching timing state machine. Data exchange between the DSP and FPGA is achieved through a hardware-level dual-port RAM.

7. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The on-grid / off-grid switching controller also integrates a switching transient event triggering waveform recording unit. The waveform recording unit is implemented using FPGA hardware resources. The triggering end of the switching transient event triggering waveform recording unit is electrically connected to the state output end of the multi-level interlocking mode switching timing state machine. The storage end of the switching transient event triggering waveform recording unit is electrically connected to the local non-volatile memory. The switching transient event triggering waveform recording unit is used to respond only to real events such as grid-connected switching, off-grid switching command issuance, and actual operation of grid-connected switches. It collects full-condition operating data within two complete power frequency cycles before and after the switching action, adds hardware timestamps, and then encrypts and stores the data. This abandons the traditional fixed-cycle timed waveform recording mode and eliminates redundant invalid waveform recording data under steady-state operating conditions.

8. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The system also includes dual-channel high-speed fiber optic communication links, which are bidirectionally connected to the grid-connected / off-grid switching controller and the energy storage converter, respectively, for complete electrical isolation. The on-grid and off-grid switching controller also integrates an optical fiber communication hardware acceleration module, which is composed of a dual-channel optical fiber communication protocol hardware parsing unit and a dual-channel optical fiber communication link redundancy switching unit cascaded together. The protocol hardware parsing unit is dedicated to parsing communication data with fixed frame length and fixed interval. The single communication cycle is no more than 100 microseconds, and there are no network congestion or data packet loss problems. The link redundancy switching unit is used to automatically and seamlessly switch to the backup channel in nanoseconds in a hardware manner when the main channel experiences a communication interruption.

9. The grid-connected energy storage and off-grid switching system according to claim 1, characterized in that, The system also includes: A system status output module is provided, wherein the input terminal of the system status output module is electrically connected to the status output terminal and the communication output terminal of the grid-connected switching controller, and the system status output module is used to output the operating status, fault type and switching waveform data of the grid-connected switching controller to the local display terminal and the remote monitoring backend, respectively.

10. The grid-connected energy storage and off-grid switching system according to claim 9, characterized in that, The system status output module includes a local status display and early warning terminal and a remote monitoring and communication gateway. The local status display and early warning terminal is used to display and monitor the operating status, fault type and switching waveform data of the off-grid switching controller in real time, and to trigger a local audible and visual alarm when the system is abnormal. The remote monitoring communication gateway is used to convert the operating status, fault alarm signals and switching waveform data of the on-grid and off-grid switching controller into standard remote communication messages and upload them to the remote monitoring backend.

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