Rural light-storage cooperative power distribution equipment with wide voltage adaptation and off-grid self-healing capabilities and operation method

Abstract

The invention discloses rural light-storage cooperative power distribution equipment with wide voltage adaptation and off-grid self-healing capabilities and an operation method, and belongs to the technical field of rural power distribution network and distributed energy cooperative control. According to the equipment, six functional modules including wide-voltage photovoltaic access, modular energy storage, intelligent switching protection, load grading power supply, edge adaptive control and dual-channel communication are highly integrated in an integrated outdoor cabinet. According to the operation method, through real-time coordination of the local edge controller, efficient absorption and active voltage support in a grid-connected state, and rapid off-grid self-healing and key load continuous power supply in case of a power grid fault are realized. According to the invention, the problems of violent voltage fluctuation, poor power supply reliability and lack of professional operation and maintenance caused by high-proportion photovoltaic access of the rural power grid are effectively solved, the method has the characteristics of'installation and use, no-grid autonomy and key supply guarantee ', and the toughness of the weak rural power grid is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of rural power distribution network and distributed energy collaborative control technology, and in particular to a rural photovoltaic-storage collaborative power distribution equipment and operation method with wide voltage adaptability and off-grid self-healing capability. It has wide voltage adaptability, fault self-healing, critical load protection and professional maintenance-free operation and maintenance capabilities, and is suitable for remote and weak rural power grid environments. Background Technology

[0002] With the implementation of the "county-wide promotion" policy for distributed photovoltaic power, rural photovoltaic installations have grown rapidly. However, rural power distribution networks generally suffer from problems such as long lines, high impedance, low short-circuit capacity, and severe voltage fluctuations. High-penetration photovoltaic systems are prone to voltage exceeding limits, harmonic distortion, reverse power flow, and islanding risks, threatening power supply security.

[0003] Existing microgrids or energy storage devices largely rely on stable communication, professional operation and maintenance, and a standard power grid environment, making reliable operation difficult in rural areas where there is "no signal, no electrician, unstable voltage, and dispersed loads." Furthermore, traditional power distribution systems use a combination of distributed equipment, resulting in complex wiring, a lack of unified control, and no differentiated power protection mechanisms for critical loads. In the event of a grid failure, all loads lose power simultaneously, impacting people's livelihoods and emergency response.

[0004] Therefore, there is an urgent need for a highly integrated, highly adaptive, easy-to-deploy, and simple-to-maintain complete photovoltaic-storage collaborative power distribution solution. Summary of the Invention

[0005] The purpose of this invention is to provide a photovoltaic-storage collaborative power distribution device and its operation method specifically tailored to the typical characteristics of rural power grids: "weak, scattered, remote, and variable." This device requires no structural modifications or large-scale investment upgrades to the existing rural power distribution network. With a high proportion of distributed photovoltaic access, it can achieve efficient local energy consumption, active grid voltage support, rapid self-healing in fault conditions, and continuous and reliable power supply to critical household loads. Simultaneously, the system possesses offline autonomous operation capabilities without external communication or professional maintenance personnel, significantly reducing the dependence of rural areas on technical manpower and truly achieving the technical goals of "ready to use, grid-free autonomy, critical power supply guarantee, and remote visibility."

[0006] To achieve the above objectives, the present invention provides a photovoltaic-storage collaborative power distribution device adapted to rural power grids.

[0007] This invention effectively addresses the core pain points of high-proportion photovoltaic grid connection in rural areas, such as severe voltage fluctuations, frequent power outages, and weak operation and maintenance capabilities, through three major innovations: high hardware integration, localized control algorithms, and lightweight interaction methods. It provides a complete technical solution for building a safe, reliable, intelligent, and inclusive new rural power system.

[0008] A rural photovoltaic-storage collaborative power distribution device with wide voltage adaptability and off-grid self-healing capability is provided. The device is integrated into a standardized outdoor cabinet with a protection level of at least IP54. Internally, a main AC bus with a rated current of 250A is formed by high-conductivity copper busbars, and inter-module control signal interaction is achieved through an industrial-grade CAN 2.0B bus. The device includes:

[0009] The photovoltaic access unit has its input end connected to the photovoltaic module array and its output end connected to the intelligent switching and protection unit through the main AC bus, which is used to convert photovoltaic DC power into AC power and feed it into the system.

[0010] The modular energy storage unit has its DC side connected to the photovoltaic access unit and the energy storage converter via a high-voltage DC bus, and its AC side connected to the intelligent switching and protection unit via the main AC bus.

[0011] The intelligent switching and protection unit is connected in series between the power grid incoming line and the main AC bus to switch between grid-connected and off-grid modes and provide residual current and surge protection; the control terminal of the intelligent switching and protection unit receives instructions from the edge adaptive control unit to execute switching actions.

[0012] The critical load graded power supply unit has its input end connected to the main AC bus and its output end connected to the first-level, second-level, and third-level load circuits respectively. The critical load graded power supply unit includes multiple intelligent miniature circuit breakers, which are used to remotely open and close and monitor the current of each level of load according to the instructions received from the edge adaptive control unit.

[0013] The edge adaptive control unit, as the core controller, has its signal acquisition terminal connected to the voltage / current sensor of the main AC bus, and its command output terminal connected to the photovoltaic access unit, modular energy storage unit, intelligent switching and protection unit, critical load graded power supply unit and virtual load unit through the CAN 2.0B bus.

[0014] The virtual load unit has its input end connected to the main AC bus and its control end receiving instructions from the edge adaptive control unit. It is used to put a resistive load into the local area when there is overvoltage and the energy storage unit can no longer absorb power, so as to consume excess photovoltaic power generation locally.

[0015] Furthermore, the photovoltaic access unit is equipped with a low-voltage ride-through circuit and a dynamic reactive power regulation module, supporting a wide voltage input of 160V-280V and providing reactive power support when the grid voltage is abnormal; it maintains grid-connected operation when the grid voltage drops to 20% of the rated value for 0.15 seconds, meeting the requirements of GB / T 19964-2012 standard; and it can operate stably for more than 0.5 seconds under a 30% voltage drop condition.

[0016] Furthermore, the modular energy storage unit adopts lithium iron phosphate battery modules with a single module capacity of 5–10 kWh, supporting parallel expansion of 2–10 modules; the battery management system monitors the voltage, temperature, state of charge and health of individual cells in real time, and performs active balancing control; the heat dissipation method is natural air cooling, with internal airflow ducts and temperature control louvers, and the operating temperature range is -20℃ to +55℃.

[0017] Furthermore, the intelligent switching and protection unit integrates a residual current device (RCD), a multi-stage lightning surge protector, and a dual power supply switching switch; the RCD's operating threshold is no greater than 30 mA, and the surge protector's nominal discharge current is no less than 20 kA.

[0018] Furthermore, the critical load graded power supply unit realizes remote opening and closing of load circuits and current monitoring through intelligent circuit breaker array; it supports the temporary upgrading of the load level of user circuits through village-level mobile management terminals, with an upgrade validity period of 1–24 hours, after which the original level is automatically restored.

[0019] Furthermore, the edge adaptive control unit is configured to: collect grid voltage and frequency information in real time, combine photovoltaic power output and energy storage status, generate and issue coordinated control commands to dynamically coordinate and control the reactive power output of photovoltaic access units, the charging and discharging of energy storage units, the mode switching of intelligent switching and protection units, the switching of load-level power supply units, and the input of virtual load units, so as to execute the whole process control logic of grid connection absorption, active voltage support, off-grid self-healing operation and grid restoration.

[0020] Furthermore, the edge adaptive control unit is configured to execute the following voltage regulation strategy:

[0021] When the voltage at the end of the line is detected to be continuously higher than 253V or lower than 198V for more than 10 seconds,

[0022] If there is overvoltage, the modular energy storage unit is controlled to absorb active power and generate inductive reactive power. If necessary, the virtual load unit is activated to absorb excess photovoltaic power locally.

[0023] If there is an undervoltage condition, the modular energy storage unit is controlled to release active power and generate capacitive reactive power.

[0024] By dynamically adjusting the active / reactive power output, the voltage is stabilized within the range of 220V±7%.

[0025] Furthermore, the entire device is encapsulated in a standardized outdoor cabinet with a protection level of not less than IP54. The cabinet is made of galvanized steel or stainless steel, with a cable inlet hole and grounding terminal reserved at the bottom, and a ventilation and heat dissipation grille at the top. It supports overall hoisting or forklift handling, and the on-site deployment time does not exceed 4 hours, requiring no concrete foundation.

[0026] An operation method for a rural photovoltaic-storage co-generation power distribution device with wide voltage adaptability and off-grid self-healing capability, applied to the device described above, the method comprising the following steps:

[0027] S1: Grid-connected optimized operation and consumption: In grid-connected operation, the output power of the photovoltaic access unit is given priority to supply the local load; the edge adaptive control unit obtains the output power of the photovoltaic access unit and the total power of the local load in real time; if the photovoltaic output is greater than the load demand, the excess power is given priority to charge the modular energy storage unit; when the energy storage charge status reaches 90%, the remaining photovoltaic power generation is fed into the grid after metering.

[0028] S2: Active Voltage Over-Limit Support: The edge adaptive control unit continuously monitors the grid connection point voltage; when the voltage remains above 253V or below 198V for 10 seconds, a voltage support strategy is activated: for overvoltage, the energy storage unit is instructed to absorb active power and issue inductive reactive power, and the virtual load unit is determined based on the real-time state of charge of the energy storage; for undervoltage, the energy storage unit is instructed to release active power and issue capacitive reactive power; using the processing results, the voltage is adjusted to within the range of 220V±7%;

[0029] S3: Grid Fault Detection and Off-Grid Self-Healing: When the edge adaptive control unit detects a grid voltage interruption, frequency mutation, or severe distortion lasting for more than 200 ms, it dynamically adjusts the islanding detection threshold based on the online identified grid impedance parameters and performs composite criterion detection. After confirming islanding, it sends a disconnect command to the intelligent switching and protection unit to control it to disconnect the grid connection point. Then, it controls the energy storage unit to switch to voltage source mode to establish an off-grid voltage reference and instructs the photovoltaic access unit to switch to off-grid mode. At the same time, it supplies power to only the first-level critical loads through the critical load hierarchical power supply unit. When the energy storage charge status is detected to be below 20% and the expected support time is less than 30 minutes, it further disconnects some first-level loads and pushes an alarm.

[0030] S4: Grid restoration and automatic synchronization: When the edge adaptive control unit detects that the external grid voltage and frequency have returned to the normal range for 10 consecutive seconds, it performs synchronization detection; after confirming that the voltage, frequency and phase deviations meet the synchronization conditions, it sends a closing command to the intelligent switching and protection unit to restore grid connection, and instructs the key load graded power supply unit to gradually restore the power supply of each load according to the priority order.

[0031] S5: Full Data Upload and Remote Interaction: The edge adaptive control unit uploads the operating status, events, and alarm data generated in steps S1 to S4 to the remote management platform via 4G or Beidou dual channels; at the same time, it receives and executes remote commands from the village-level mobile management terminal to achieve temporary adjustments to the load level.

[0032] Furthermore, in S4, it is confirmed that the voltage, frequency, and phase deviations all meet the synchronization conditions, specifically: voltage amplitude deviation < 5V, frequency deviation < 0.2Hz, and phase difference < 5°.

[0033] The present invention has the following beneficial effects:

[0034] 1. Strong wide voltage adaptability, improving grid connection stability and energy utilization: The photovoltaic access unit supports a wide range of AC voltage input from 160V to 280V and has enhanced low voltage ride-through and dynamic reactive power regulation functions. It can adapt to the common low voltage or overvoltage conditions of rural power grids, maintain grid connection operation when the grid voltage fluctuates, effectively reduce the ineffective grid disconnection time of photovoltaic power generation, and improve the local consumption rate of distributed energy.

[0035] 2. Modular energy storage and off-grid self-healing ensure continuous power supply: Standardized, hot-swappable lithium iron phosphate energy storage modules are adopted, supporting flexible online capacity expansion. Combined with intelligent switching and edge control, it can seamlessly switch to off-grid operation mode within 500ms after a grid fault. The energy storage unit establishes a voltage reference to ensure uninterrupted power supply to critical loads such as village clinics and communication base stations, greatly improving power supply reliability.

[0036] 3. Integrated and intelligent protection for maintenance-free operation: Power generation, energy storage, power distribution, protection, and control functions are highly integrated into a single protective cabinet, allowing for quick on-site deployment (≤4 hours) without complex wiring or concrete foundations. It integrates high-sensitivity residual current protection and lightning surge protection, and achieves localized autonomous operation through edge adaptive control algorithms, reducing reliance on on-site maintenance by professional technicians.

[0037] 4. Load tiered management and dynamic adjustment enhance the flexibility of power supply guarantee: The intelligent circuit breaker array enables three-level management of the load and supports village-level administrators to temporarily upgrade the load level via mobile terminals, realizing refined management and dynamic adjustment of power supply guarantee strategies, balancing the reliability of people's livelihood guarantee with the flexibility of power supply management.

[0038] 5. Edge intelligence and adaptive control enhance system environmental adaptability: The edge control unit has the ability to identify rural power grid characteristics online and can dynamically adjust the parameter thresholds of control strategies such as voltage support and islanding detection to match the "weak and scattered" characteristics of the local power grid, thereby improving the effectiveness and accuracy of control and ensuring that the system can operate stably and reliably in different rural power grid environments.

[0039] 6. Dual-channel redundant communication ensures full-area status visibility and management accessibility: Integrating 4G and Beidou short message dual-mode communication, even in remote areas without public network signals, key operating status and alarm information can be reported regularly via Beidou satellite, realizing remote visual management of equipment operating status and issuance of emergency commands, opening up the "last mile" operation and maintenance channel for rural power. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating an operation method for a rural photovoltaic-storage collaborative power distribution device with wide voltage adaptability and off-grid self-healing capability, as provided in an embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some 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.

[0042] This invention provides a rural photovoltaic-storage collaborative power distribution device with wide voltage adaptability and off-grid self-healing capabilities. The device is integrated into a standardized outdoor protective cabinet. The cabinet is made of 2.0 mm thick galvanized steel or 304 stainless steel, with a UV-resistant and salt spray-resistant anti-corrosion coating. Its protection level is no less than IP54, fully meeting the requirements of GB 4208-2017 standards, and can withstand common rural environments such as dust, rain, insects, and mild corrosion. The cabinet has compact dimensions of 1800 mm (height) × 800 mm (width) × 600 mm (depth), facilitating transportation and installation. The bottom has four Φ30 mm cable entry holes and an M12 grounding terminal, supporting flexible multi-line routing. The top features a louvered ventilation grille with insect screens, and the interior has vertical airflow ducts, utilizing natural convection for efficient heat dissipation, eliminating the need for fans, air conditioners, or other active cooling equipment, significantly reducing system failure rate and maintenance complexity. The entire unit can be hoisted or transported by forklift. On-site deployment only requires connecting the power grid input line, photovoltaic input line, user output line and grounding wire. Installation and commissioning can be completed within 4 hours. No concrete foundation, professional debugging tools or complicated wiring are required, making it particularly suitable for remote villages with limited road conditions.

[0043] The internal functional modules of the equipment are connected by high-conductivity copper busbars to form a main AC bus with a rated current of 250 A and a temperature rise of ≤40 K, realizing the main circuit electrical interconnection between the photovoltaic access unit, energy storage unit, load output line and grid connection point; the control signal is realized through industrial-grade CAN 2.0B bus (baud rate 500 kbps, communication distance ≥50 m) to achieve high-speed and anti-interference data interaction, ensuring that the edge adaptive control unit can schedule other modules in real time.

[0044] All functional modules adopt a modular plug-and-play structure with standardized interfaces, supporting hot-swappable expansion and rapid replacement of faulty modules. After adding energy storage modules or replacing photovoltaic units, the system can complete module identification, parameter synchronization, and control authority transfer within 5 seconds via the CAN bus, ensuring the continuity and reliability of operation.

[0045] I. Photovoltaic Grid Connection Unit

[0046] This unit adopts a single-phase or three-phase string inverter architecture, with a rated power ranging from 5 to 30 kW, suitable for village-level photovoltaic power stations of different sizes. Its core advantage lies in its strong adaptability to voltage fluctuations in rural power grids. In some rural areas of my country, due to long lines and light loads, nighttime voltage often reaches over 260V; while during the day, when the load is concentrated, the voltage may drop below 170V. Traditional inverters are prone to frequent grid disconnection under such conditions, resulting in ineffective photovoltaic utilization. This unit solves this problem through the following technical means:

[0047] (1) Wide-range MPPT control: It integrates the variable step size perturbation observation method (P&O) and the open circuit voltage ratio method (OCV). Even under conditions of rapid changes in illumination, such as cloud cover or partial component shading, it can still quickly and accurately track the maximum power point with an MPPT efficiency of ≥99.5%.

[0048] (2) Enhanced Low Voltage Ride-Through (LVRT): Not only does it meet the LVRT requirements of GB / T 19964-2012 for distributed power sources below 10 kV, maintaining operation for 0.15 seconds when the voltage drops to 20% of the rated value, but it can also operate stably for more than 0.5 seconds under a 30% voltage drop condition, significantly improving the grid connection stability of the system under weak grid conditions, as shown in Formula 5, where, Let be the commanded reactive current value to be injected into the grid, k be the reactive power injection coefficient, and U be the current grid voltage per unit value. Rated current of the photovoltaic access unit:

[0049]

[0050] (3) Dynamic reactive power compensation: Supports continuously adjustable power factor from -0.9 to +0.9, with a response time ≤200 ms. The system automatically adjusts reactive power output based on the local measured voltage value: when the voltage >253V, it outputs inductive reactive power (Q<0); when the voltage <198V, it outputs capacitive reactive power (Q>0), effectively suppressing voltage over-limit, as shown in Formula 6, where PF is the power factor, P is the active power, and Q is the reactive power. This definition ensures that the power factor is always continuously adjustable within the set range when the system adjusts reactive power.

[0051]

[0052] (4) Harmonic suppression: Using LCL filter and digital control algorithm, the total harmonic distortion (THD) is ≤3%, which meets the high power quality requirements of sensitive loads such as rural medical care and communication.

[0053] II. Modular Energy Storage Unit

[0054] The energy storage system is the core of achieving off-grid self-healing and voltage support. This unit uses lithium iron phosphate cells, which have advantages such as high safety, long life, and wide temperature range adaptability. A single module consists of 16 series of 100 Ah cells, with a nominal voltage of 48V and a capacity of 5–10 kWh. Multiple modules can be connected in parallel to expand the total capacity to over 50 kWh, meeting the 8–12 hour power supply needs of critical village loads, as shown in Formula 7. For the output power of the photovoltaic unit, This represents the output power of the energy storage unit (a positive value indicates discharge). This represents the total active power of the primary critical load.

[0055]

[0056] Each module has a built-in independent BMS with the following functions:

[0057] (1) Real-time acquisition of voltage (16 channels, accuracy ±5 mV) and temperature (8 NTC points, accuracy ±1℃) of each battery cell.

[0058] (2) An SOC estimation algorithm based on ampere-hour integration and open-circuit voltage (OCV) correction. This algorithm accumulates the change in charge through real-time integration and performs periodic correction by combining the open-circuit voltage, ensuring that the estimation error is <3% under complex operating conditions, as shown in Formula 8, where, The current state of charge. The initial state of charge. For the battery's rated capacity, for The charging and discharging current at any given time (discharging is positive). For coulomb efficiency, the error is less than 3%;

[0059]

[0060] (3) SOH assessment based on internal resistance increment (IC) and capacity decay model;

[0061] (4) Active balancing circuit, balancing current 0.5 A, supports both trickle balancing and fast balancing modes;

[0062] (5) Multiple protections: overvoltage (>3.65V / cell), undervoltage (<2.5V), overcurrent (>150 A), overtemperature (>60℃), short circuit, etc.

[0063] The heat dissipation design abandons the traditional fan and adopts pure natural air cooling: the module is installed vertically with a gap of ≥50 mm between the front and rear air ducts; the top louvers are driven by a temperature control actuator, which automatically opens when the internal temperature is >45℃ to accelerate the exhaust of hot air; when the ambient temperature is <0℃, the system automatically limits the charging current (≤0.2C) to prevent low-temperature lithium plating and ensure battery safety.

[0064] For capacity expansion, new modules are connected via a standard quick-connect interface, which integrates a high-voltage DC busbar (rated 200A), a CAN communication line, and an NTC temperature line. The system automatically completes module identification, parameter synchronization, and initial equalization within 5 seconds of power-on, without any manual intervention, truly achieving "plug and play".

[0065] III. Intelligent Switching and Protection Unit

[0066] This unit acts as the "gatekeeper" for the safe operation of the system. It integrates the following key components:

[0067] (1) RCD: 30 mA high-sensitivity residual current protection, with an action time ≤0.1 s, effectively preventing electric shock accidents in humid rural environments;

[0068] (2) SPD: Class II+III composite surge protector, In=20 kA, Imax=40 kA, which can withstand surge impacts of several kilovolts caused by direct lightning strikes or induced lightning strikes;

[0069] (3) ATS: Rated current 100–250 A, mechanical life ≥10,000 times, switching time ≤100 ms.

[0070] In the event of a grid fault, this unit works in conjunction with the edge controller: disconnecting the grid-connected contactor within 200 ms; islanding detection employs a composite criterion of Active Frequency Shift (AFD) and Voltage Phase Jump (VJP), but its detection threshold is not fixed, but dynamically adjusted based on the grid characteristics identified online by the edge adaptive control unit: in high-impedance weak grids (R / X > 2 and SCC < 5 MVA), the active frequency shift automatically decreases from the conventional 0.5 Hz / s to 0.2 Hz / s, and the voltage jump trigger threshold is correspondingly relaxed, thereby significantly reducing the false alarm rate while ensuring detection reliability. The entire detection and switching process is completed within 500 ms, ensuring a fast, reliable, and shock-free switching process, as shown in Equation 9, where... The system frequency change rate, Based on the line resistance R, reactance X, and short-circuit capacity The frequency change rate trigger threshold is dynamically calculated.

[0071]

[0072] IV. Critical Load Tiered Power Supply Unit

[0073] This unit consists of 8–16 intelligent miniature circuit breakers, each corresponding to one user circuit. The circuit breakers support remote opening and closing, real-time current monitoring, and overload / short-circuit protection.

[0074] The load level preset logic is as follows:

[0075] (1) Level 1: Power outages will directly threaten life safety or public order, such as health clinics, communication base stations, and drought relief water pumps;

[0076] (2) Level 2: Affecting basic public services, such as village committees and schools;

[0077] (3) Level 3: Ordinary residential electricity.

[0078] Through a lightweight mobile application, village administrators can perform a "temporary upgrade" operation: select the target loop → set the level → enter the verification code → set the validity period. The system automatically updates the scheduling table and restores the original level after the expiration. This mechanism has extremely practical value during special periods, such as drought relief.

[0079] V. Edge Adaptive Control Unit

[0080] As the system's "brain," this unit employs an ARM Cortex-A9 dual-core processor (800 MHz) and runs a Linux real-time operating system, possessing powerful local computing capabilities. Its core algorithms include:

[0081] (1) Power Grid Characteristic Identification: Based on local measurement data such as voltage, current, power, and frequency, the line impedance Z=R+jX is identified online using the recursive least squares (RLS) method, and the short-circuit capacity SCC is estimated. When R / X > 2 and SCC < 5 MVA, it is determined to be a typical rural weak network, and the enhanced control strategy is automatically activated, as shown in Formula 10, where For short-circuit capacity, Here, R is the system nominal voltage, and X is the identified equivalent resistance and reactance of the line, respectively.

[0082]

[0083] (2) Active voltage support: Dynamically adjust the active / reactive power output of energy storage, and activate virtual loads to absorb excess photovoltaic power locally when necessary, avoiding overvoltage caused by backfeeding, as shown in Formula 11, where The readings are real-time measurements from a local voltage sensor.

[0084]

[0085] (3) Islanding detection and black start: Composite criteria ensure detection time ≤200 ms; In off-grid mode, energy storage establishes voltage reference, photovoltaic switches to V / f control, and supplies only primary loads;

[0086] (4) Offline autonomy: When communication is interrupted, more than 20 kinds of running scenario logic in the preset strategy library can still be executed, with a control cycle of ≤100 ms, ensuring that the system "does not paralyze without network".

[0087] VI. Simplified Communication and Remote Terminals

[0088] The communication module supports 4G Cat.1 (full network compatibility) and BeiDou RDSS dual-channel. In areas without 4G, BeiDou reports critical status (e.g., SOC=45%, off-network operation, Level 1 load online) every 10 minutes, with the message format compressed to within 70 bytes. Alarm tiered push notifications are also provided.

[0089] (1) General (e.g., SOC < 30%): Lightweight mobile application notifications;

[0090] (2) Important (e.g., BMS failure): Lightweight mobile application notifications + SMS;

[0091] (3) Emergency (e.g., battery overheating > 60°C): Lightweight mobile application notification + SMS + voice call.

[0092] Village administrators can view real-time data, historical curves, and event logs through a lightweight mobile application, and perform operations such as load escalation and remote reset, truly realizing "one mobile phone to manage the electricity consumption of the whole village".

[0093] VII. Virtual Load Unit

[0094] The virtual load unit is a 10 kW adjustable resistive load composed of a nickel-chromium alloy resistor array controlled by solid-state relays, with an IP54 protection rating, and installed in an independent heat dissipation chamber inside the equipment cabinet. When the system determines that there is a risk of continuous overvoltage and the energy storage SOC is ≥95%, the edge control unit automatically switches on part or all of the virtual load to consume excess photovoltaic power, with a switching response time ≤200 ms. This design effectively solves the problem of "nowhere to consume and forced curtailment" during peak photovoltaic power generation periods in rural areas, while avoiding voltage over-limit caused by backfeeding.

[0095] This invention also provides an operation method for the above-mentioned photovoltaic-storage coordinated power distribution equipment, such as... Figure 1 It includes the following five core steps:

[0096] S1: Grid-connected optimized operation and consumption: Prioritize supplying local loads with photovoltaic power generation; if photovoltaic output exceeds load demand and energy storage SOC is below 90%, excess electricity is charged into the energy storage unit; if the energy storage is full, surplus electricity is metered and fed into the grid; the system can also optimize charging and discharging strategies by combining time-of-use pricing signals to achieve economical operation, as shown in Formula 3, where... This refers to the output power of the photovoltaic unit. This represents the total active power of the local load. This represents the power of the energy storage unit; a positive value indicates discharging, and a negative value indicates charging. This represents the power exchanged with the external power grid; a positive value indicates power being supplied to the grid.

[0097]

[0098] S2: Active Voltage Over-Limit Support: When the grid voltage is detected to be continuously exceeding 253V or falling below 198V for more than 10 seconds, a voltage support strategy is activated: During overvoltage, energy storage absorbs active power and generates inductive reactive power; if necessary, virtual loads are activated to locally absorb excess photovoltaic power. During undervoltage, energy storage releases active power and generates capacitive reactive power to stabilize the voltage within the range of 220V±7%, as shown in Formula 4. This refers to the voltage deviation at the end of the line. and These are the equivalent resistance and reactance of the line, respectively. and These are the active and reactive current components flowing through the line, respectively.

[0099]

[0100] S3: Grid Fault Detection and Off-Grid Self-Healing: When a grid loss of voltage or severe distortion, such as voltage interruption, frequency mutation, or harmonic distortion, is detected and lasts for more than 200 ms, the islanding switching process is executed: disconnecting the grid connection point, establishing an off-grid voltage reference, switching the photovoltaic system to off-grid mode, and supplying power only to primary critical loads; the system periodically assesses the remaining energy storage capacity, and if the expected support time is less than 30 minutes, it will prompt the start of emergency power sources such as diesel generators through a lightweight mobile application alarm.

[0101] S4: Grid Restoration and Automatic Synchronization: When the external grid voltage stabilizes (meeting 198–253V and frequency 49.5–50.5Hz for 10 consecutive seconds), the system performs synchronization detection. After confirming that the voltage amplitude deviation is <5V, the frequency deviation is <0.2Hz, and the phase difference is <5°, the system automatically closes the grid connection point switch, restores grid-connected operation, and gradually restores secondary and tertiary loads according to priority to avoid impacting the grid.

[0102] S5: Full-process data upload and remote interaction: The entire process operation data is uploaded to the county-level energy management platform through dual channels of 4G or Beidou short message; abnormal events generate structured alarm information, which is pushed to village-level administrators and county-level operation and maintenance personnel through a lightweight mobile application, supporting remote diagnosis, parameter adjustment and historical data analysis.

[0103] This invention effectively solves the pain points of voltage fluctuations, power outages, and maintenance difficulties caused by high-proportion photovoltaic grid connection in rural areas through a highly integrated hardware platform, intelligent local control algorithms, and user-friendly village-level interactive design. It achieves a technological breakthrough of "autonomy without grid connection, rapid self-healing of faults, key guarantees, and maintenance via mobile phone", and has significant social benefits and promotional value.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A rural photovoltaic-storage co-generation power distribution device with wide voltage adaptability and off-grid self-healing capability, characterized in that, The entire device is integrated into a standardized outdoor cabinet with a protection level of not less than IP54. Internally, a main AC bus with a rated current of 250 A is formed by high-conductivity copper busbars, and inter-module control signal exchange is achieved through an industrial-grade CAN 2.0B bus. The device includes: The photovoltaic access unit has its input end connected to the photovoltaic module array and its output end connected to the intelligent switching and protection unit through the main AC bus, which is used to convert photovoltaic DC power into AC power and feed it into the system. The modular energy storage unit has its DC side connected to the photovoltaic access unit and the energy storage converter via a high-voltage DC bus, and its AC side connected to the intelligent switching and protection unit via the main AC bus. The intelligent switching and protection unit is connected in series between the power grid incoming line and the main AC bus to switch between grid-connected and off-grid modes and provide residual current and surge protection; the control terminal of the intelligent switching and protection unit receives instructions from the edge adaptive control unit to execute switching actions. The critical load graded power supply unit has its input end connected to the main AC bus and its output end connected to the first-level, second-level, and third-level load circuits respectively. The critical load graded power supply unit includes multiple intelligent miniature circuit breakers, which are used to remotely open and close and monitor the current of each level of load according to the instructions received from the edge adaptive control unit. The edge adaptive control unit, as the core controller, has its signal acquisition terminal connected to the voltage / current sensor of the main AC bus, and its command output terminal connected to the photovoltaic access unit, modular energy storage unit, intelligent switching and protection unit, critical load graded power supply unit and virtual load unit through the CAN 2.0B bus. The virtual load unit has its input end connected to the main AC bus and its control end receiving instructions from the edge adaptive control unit. It is used to put a resistive load into the local area when there is overvoltage and the energy storage unit can no longer absorb power, so as to consume excess photovoltaic power generation locally.

2. The device as described in claim 1, characterized in that, The photovoltaic access unit is equipped with a low voltage ride-through circuit and a dynamic reactive power regulation module, supporting a wide voltage input of 160V-280V and providing reactive power support when the grid voltage is abnormal; it maintains grid-connected operation when the grid voltage drops to 20% of the rated value for 0.15 seconds, meeting the requirements of GB / T 19964-2012 standard; and it can operate stably for more than 0.5 seconds under a 30% voltage drop condition.

3. The device as described in claim 1, characterized in that, The modular energy storage unit uses lithium iron phosphate battery modules with a single module capacity of 5–10 kWh and supports parallel expansion of 2–10 modules. The battery management system monitors the voltage, temperature, state of charge and health of individual cells in real time and performs active balancing control. The heat dissipation method is natural air cooling, with internal airflow ducts and temperature control louvers, and the operating temperature range is -20℃ to +55℃.

4. The photovoltaic-storage coordinated power distribution equipment as described in claim 1, characterized in that, The intelligent switching and protection unit integrates a residual current device (RCD), a multi-stage lightning surge protector, and a dual power supply switching switch; the RCD's operating threshold is no greater than 30 mA, and the surge protector's nominal discharge current is no less than 20 kA.

5. The device as described in claim 1, characterized in that, The critical load tiered power supply unit realizes remote opening and closing of load circuits and current monitoring through intelligent circuit breaker arrays; it supports the temporary upgrading of the load level of user circuits through village-level mobile management terminals, with an upgrade validity period of 1–24 hours, after which the original level is automatically restored.

6. The device as described in claim 1, characterized in that, The edge adaptive control unit is configured to: collect grid voltage and frequency information in real time, combine photovoltaic power output and energy storage status, generate and issue coordinated control commands to dynamically coordinate and control the reactive power output of photovoltaic access units, the charging and discharging of energy storage units, the mode switching of intelligent switching and protection units, the switching of load-level power supply units, and the input of virtual load units, so as to execute the whole process control logic of grid connection absorption, active voltage support, off-grid self-healing operation and grid restoration.

7. The device as described in claim 6, characterized in that, The edge adaptive control unit is configured to execute the following voltage regulation strategy: When the voltage at the end of the line is detected to be continuously higher than 253V or lower than 198V for more than 10 seconds, If there is overvoltage, the modular energy storage unit is controlled to absorb active power and generate inductive reactive power. If necessary, the virtual load unit is activated to absorb excess photovoltaic power locally. If there is an undervoltage condition, the modular energy storage unit is controlled to release active power and generate capacitive reactive power. By dynamically adjusting the active / reactive power output, the voltage is stabilized within the range of 220V±7%.

8. The device as described in claim 1, characterized in that, The equipment is enclosed in a standardized outdoor cabinet with a protection level of not less than IP54. The cabinet is made of galvanized steel or stainless steel, with a cable inlet hole and grounding terminal at the bottom and a ventilation and heat dissipation grille at the top. It supports overall hoisting or forklift handling, and the on-site deployment time does not exceed 4 hours. No concrete foundation is required.

9. An operation method for rural photovoltaic-storage co-generation power distribution equipment with wide voltage adaptability and off-grid self-healing capability, characterized in that, The method, applied to the device as described in any one of claims 1 to 7, comprises the following steps: S1: Grid-connected optimized operation and consumption: In grid-connected operation, the output power of the photovoltaic access unit is given priority to supply the local load; the edge adaptive control unit obtains the output power of the photovoltaic access unit and the total power of the local load in real time; if the photovoltaic output is greater than the load demand, the excess power is given priority to charge the modular energy storage unit; when the energy storage charge status reaches 90%, the remaining photovoltaic power generation is fed into the grid after metering. S2: Active Voltage Over-Limit Support: The edge adaptive control unit continuously monitors the grid connection point voltage; when the voltage remains above 253V or below 198V for 10 seconds, a voltage support strategy is activated: for overvoltage, the energy storage unit is instructed to absorb active power and issue inductive reactive power, and the virtual load unit is determined based on the real-time state of charge of the energy storage; for undervoltage, the energy storage unit is instructed to release active power and issue capacitive reactive power; using the processing results, the voltage is adjusted to within the range of 220V±7%; S3: Grid Fault Detection and Off-Grid Self-Healing: When the edge adaptive control unit detects a grid voltage interruption, frequency mutation, or severe distortion lasting for more than 200 ms, it dynamically adjusts the islanding detection threshold based on the online identified grid impedance parameters and performs composite criterion detection. After confirming islanding, it sends a disconnect command to the intelligent switching and protection unit to control it to disconnect the grid connection point. Then, it controls the energy storage unit to switch to voltage source mode to establish an off-grid voltage reference and instructs the photovoltaic access unit to switch to off-grid mode. At the same time, it supplies power to only the first-level critical loads through the critical load hierarchical power supply unit. When the energy storage charge status is detected to be below 20% and the expected support time is less than 30 minutes, it further disconnects some first-level loads and pushes an alarm. S4: Grid restoration and automatic synchronization: When the edge adaptive control unit detects that the external grid voltage and frequency have returned to the normal range for 10 consecutive seconds, it performs synchronization detection; after confirming that the voltage, frequency and phase deviations meet the synchronization conditions, it sends a closing command to the intelligent switching and protection unit to restore grid connection, and instructs the key load graded power supply unit to gradually restore the power supply of each load according to the priority order. S5: Full Data Upload and Remote Interaction: The edge adaptive control unit uploads the operating status, events, and alarm data generated in steps S1 to S4 to the remote management platform via 4G or Beidou dual channels; at the same time, it receives and executes remote commands from the village-level mobile management terminal to achieve temporary adjustments to the load level.

10. The method as described in claim 9, characterized in that, In S4, it is confirmed that the voltage, frequency, and phase deviations all meet the synchronization conditions, specifically: voltage amplitude deviation < 5V, frequency deviation < 0.2Hz, and phase difference < 5°.

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