A photovoltaic and v2l cooperative energy storage system charging control method and system

Abstract

The application provides a photovoltaic and V2L collaborative energy storage system charging control method and system, defines V2L provided by an electric vehicle battery as a real-time compensation source of photovoltaic power fluctuation, forms a collaborative control closed loop with a photovoltaic input source, utilizes V2L to compensate for instantaneous fluctuation of photovoltaic power in real time, maintains stability of total charging power of an energy storage system, the method first evaluates photovoltaic power fluctuation by using maximum available power of photovoltaic and a photovoltaic power change rate, if fluctuation amplitude reaches a threshold value that needs to be compensated, automatically calculates a power shortage, and immediately increases discharging power of V2L to compensate for the shortage, and maintains stability of total charging power of an energy storage battery of the energy storage system; the application can utilize millisecond-level fast response characteristics of V2L, compensate for instantaneous fluctuation of photovoltaic power caused by factors such as cloud cover in real time, and maintain stability of total charging power of an energy storage system.

Description

Technical Field

[0001] This invention relates to the fields of energy storage power supply technology, photovoltaic power generation technology, and electric vehicle V2L (Vehicle-to-Load) discharge technology, and in particular to a charging control method and system for a photovoltaic and V2L coordinated energy storage system. Background Technology

[0002] Photovoltaic power generation has the advantages of being clean and renewable, but its output power is significantly intermittent and fluctuates due to the influence of sunlight conditions. When clouds block photovoltaic panels, the output power can drop rapidly by tens of percentage points, with a rate of change reaching 50%-90% of the rated power per second. This sudden drop in power causes drastic fluctuations in the charging current of the energy storage system, subjecting the batteries to frequent current surges, accelerating their cycle aging and capacity decay, and in severe cases, even triggering system protection, leading to charging interruptions.

[0003] To address the issue of photovoltaic power fluctuations, various technical solutions have been disclosed in the existing technology, mainly including the following categories:

[0004] (I) Photovoltaic and energy storage synergistic control scheme.

[0005] The published patent CN112510737B proposes a photovoltaic energy storage charging station on-grid and off-grid coordinated control method and system. By establishing a photovoltaic energy storage charging station microgrid system, it achieves coordinated control between photovoltaic power generation units and energy storage units, switching between grid-connected and off-grid modes to maintain power balance and voltage stability of the microgrid system. CN113765127A proposes a multi-station integrated photovoltaic-energy storage-charging-swapping coordinated control method. It divides a cycle into three stages based on historical load energy consumption: peak electricity price period, normal period, and off-peak electricity price period, and sets operating modes for each stage to achieve power exchange between the photovoltaic-energy storage-charging-swapping microgrid system and the main grid. CN113690873A proposes a photovoltaic DC microgrid coordinated control method incorporating hybrid energy storage. It uses a hybrid energy storage system to coordinate the control of the photovoltaic DC microgrid to address the intermittency and volatility of photovoltaic power generation. CN122456508A proposes a method for output power fluctuation compensation control of an energy storage photovoltaic power generation system. The method determines voltage and power response parameters based on the output power change and voltage change, identifies the direction of power surge or drop and calculates the excess amplitude, and generates compensation commands based on the excess amplitude and the fast energy storage unit.

[0006] The common feature of the above-mentioned solutions is that they all use energy storage batteries as the primary means of mitigating photovoltaic (PV) fluctuations. Some solutions employ a hybrid energy storage system composed of supercapacitors and batteries to balance energy density and power density. However, at the system level, the response speed of energy storage batteries in fluctuation compensation is limited by BMS communication latency and the response time of the system control architecture. In traditional solutions, the inverter, BMS, and EMS are located in different physical modules, and the modules communicate through industrial protocols, resulting in inherent protocol conversion delays (typically on the order of 100 milliseconds) and the risk of state synchronization failure. The BMS data refresh cycle in traditional solutions can reach several seconds, and the SOC estimation deviation may exceed 5%. PV power drops occur on a millisecond timescale, and the aforementioned communication delays and system response times are difficult to match the rapid changes in PV fluctuations. Furthermore, the charging and discharging capacity of a single energy storage battery is limited when the SOC is too high or too low, and it cannot provide effective fluctuation compensation when the energy storage system itself is low on power. This is precisely the problem that hybrid energy storage solutions (batteries and supercapacitors) attempt to solve.

[0007] (II) Integrated control scheme for photovoltaic, energy storage and charging.

[0008] The published patent CN112531760B proposes an integrated photovoltaic-storage-charging hierarchical coordinated control system and its control strategy. Through a hierarchical coordinated control architecture, it achieves the coordinated operation of photovoltaic power generation units, energy storage units, and electric vehicle charging units. CN117254526A proposes an energy collaborative optimization control method for an integrated photovoltaic-storage-charging-detection microgrid. This method establishes load models for different time periods based on historical transformer load data and power generation models for the photovoltaic system for different time periods based on historical power generation data, achieving energy collaborative optimization. Beijing Lianyu Technology's integrated photovoltaic-storage-charging low-power V2G charging pile microgrid collaborative control device involves collecting photovoltaic current changes, observing energy storage voltage fluctuations, and identifying the electric vehicle access status.

[0009] The common characteristic of the above-mentioned solutions is that, although some involve V2G (Vehicle-to-Grid) technology, using electric vehicles as dispatchable loads or energy storage resources to participate in microgrid energy management, their control objectives are grid-level energy balance and power dispatch, rather than real-time compensation for photovoltaic fluctuations during the charging process of the energy storage system. The former pursues energy optimization on a minute-level timescale, while the latter requires power point tracking on a millisecond-level timescale. There are fundamental differences between the two in terms of control objectives, response speed, and technical approaches. Existing V2G solutions have control loop response times ranging from seconds to minutes, which cannot meet the millisecond-level compensation requirements when photovoltaic power suddenly drops.

[0010] (III) Photovoltaic power supply V2L scheme.

[0011] The academic research paper "Solar-Powered Vehicle-to-Load (V2L) Plug-in Electric Vehicles: Alleviation of the Photovoltaic Power Decay" proposes the concept of solar V2L, integrating photovoltaic technology into the power grid to charge the batteries of plug-in electric vehicles (PEVs). The PEV batteries can then act as both V2G (Vehicle-to-Grid) and V2L (Vehicle-to-Load) to supply power to the grid or loads. In this scheme, V2L acts as the power supply terminal for the load (i.e., V2L outputs power to the load), and its control objective is to optimize the extraction and utilization of photovoltaic energy. The photovoltaic system and V2L are connected in series; the photovoltaic system charges the PEV, which then supplies power to the load through the V2L. However, there is a lack of real-time coordinated control mechanism between the two.

[0012] The published patent CN120073875B proposes a photovoltaic power generation and V2H coordinated control system and its control method based on multi-mode switching, involving the coordinated control of photovoltaic power generation and V2H (Vehicle-to-Home). However, this scheme takes the power supply of household loads as the control target and does not involve using V2L / V2H as a real-time compensation source for photovoltaic power fluctuations.

[0013] (iv) Multi-source coordinated power control scheme.

[0014] The published patent CN121356002A proposes a power control method and device based on multi-source coordination and reconfigurable power matrix. In response to the charging power scheduling command, it obtains the current power supply parameter set of the multi-source power supply module (including the working parameters of the three-phase AC grid, photovoltaic module and energy storage module), and determines the on / off state of the switch group and the charging power allocation strategy according to the preset power supply mode decision strategy.

[0015] The multi-source power supply module of this solution includes a three-phase AC grid, photovoltaic modules, and energy storage modules, but does not involve V2L mobile input sources. Its power allocation strategy is based on a preset power supply mode decision-making strategy and does not involve dynamic compensation based on real-time fluctuations in photovoltaic power.

[0016] While the existing solutions for dealing with photovoltaic power fluctuations each have their own focus, none of them effectively address the problem of rapid compensation when photovoltaic power drops sharply. In summary, they mainly suffer from the following shortcomings:

[0017] First, the response speed of existing photovoltaic fluctuation compensation schemes is insufficient, making it difficult to match the millisecond-level time scale of sudden drops in photovoltaic power.

[0018] In the aforementioned photovoltaic (PV) and energy storage coordinated control schemes and integrated PV-storage-charging coordinated control schemes, compensation for PV power fluctuations primarily relies on energy storage batteries or grid dispatch. The response speed of energy storage batteries is limited by BMS communication latency and the battery's own dynamic characteristics; power adjustments typically take hundreds of milliseconds to several seconds to complete. Grid dispatch response speeds range from seconds to minutes. However, the timescale of sudden PV power drops due to factors such as cloud cover is on the millisecond scale, with PV output power potentially decreasing by tens of percentage points within tens of milliseconds. The existing schemes' response timescales are severely mismatched with the PV fluctuation timescales, causing the energy storage system's charging power to become unstable during PV power drops. This results in sudden changes in charging current, affecting charging efficiency and battery life, and may even trigger the system's overcurrent or undervoltage protection, leading to charging interruptions.

[0019] Secondly, in existing technologies, V2L is only used as a load power supply terminal, and its millisecond-level fast response characteristics have not been utilized for compensation of photovoltaic fluctuations.

[0020] In existing technologies, the role of V2L (Vehicle-to-Land) is limited to the power supply end of the load; that is, V2L outputs power to loads such as household appliances and outdoor equipment. V2L is regarded as an independent, passively responsive power source. Although solar V2L schemes in academic research involve photovoltaics charging electric vehicles, and the electric vehicles then supply power to loads through V2L, the energy transfer relationship between photovoltaics and V2L is a series relationship. Photovoltaics charge the PEV (Power Emission Vehicle), and the PEV then supplies power to the load through V2L, rather than a real-time coordinated control relationship. There is a lack of a unified scheduling mechanism between the two. V2L itself has millisecond-level fast response characteristics, but in existing technologies, this characteristic is only used to meet the power supply needs of the load and is not utilized for real-time compensation of photovoltaic fluctuations. Existing technologies have not redefined V2L from an independent power source as a real-time compensation source for photovoltaic fluctuations, thus failing to leverage the inherent advantage of V2L in response speed.

[0021] Third, the control objectives of existing photovoltaic-V2L collaborative solutions are focused on the grid or household load level, without addressing real-time compensation for photovoltaic fluctuations during the charging process of the energy storage system.

[0022] In publicly available integrated photovoltaic-storage-charging control schemes and photovoltaic power generation-V2H (V2L / V2H) control schemes, the control objectives are energy balance and power dispatch at the household load power supply or microgrid level. These schemes have response timescales ranging from seconds to minutes, and their control strategies are geared towards minute-level changes in photovoltaic output or hourly electricity price signals, rather than millisecond-level instantaneous fluctuations in photovoltaic power. Their control objectives are to optimize the extraction and utilization of photovoltaic energy, reduce household electricity costs, or participate in grid dispatch, rather than real-time compensation for photovoltaic fluctuations during energy storage system charging. Sudden drops in photovoltaic power occur within a millisecond timescale, but the response speed of existing schemes' control loops is insufficient to complete compensation within this timescale. In other words, existing schemes address slow-change problems, not the fast-change problems addressed by this invention.

[0023] Fourth, in the existing technology, there is a lack of a unified collaborative control closed loop between photovoltaic MPPT and V2L, which makes it impossible for V2L to automatically adjust the discharge power according to changes in photovoltaic power.

[0024] In publicly available multi-source collaborative power control schemes, the multi-source power supply module includes a three-phase AC grid, photovoltaic modules, and energy storage modules, but does not involve a V2L mobile input source. Its power allocation strategy is based on a preset power supply mode decision-making strategy (such as selecting the power supply mode according to time period or electricity price), which is an open-loop, rule-based decision-making approach, rather than a closed-loop dynamic compensation based on real-time fluctuations in photovoltaic power. The photovoltaic MPPT controller and V2L operate independently; the MPPT controller only tracks the photovoltaic maximum power point, and the V2L only responds to the load's power supply demand. There is no information exchange or collaborative control between the two, failing to form a unified collaborative control closed loop, and thus unable to achieve real-time collaborative control where the V2L automatically adjusts its discharge power according to changes in photovoltaic power. Summary of the Invention

[0025] This invention proposes a charging control method and system for a photovoltaic (PV) and V2L (Vehicle-to-Loop) collaborative energy storage system. For the first time, V2L is defined as a real-time compensation source for PV power fluctuations, forming a unified collaborative control closed loop with the PV input source. Its core design concept lies in utilizing the millisecond-level fast response characteristics of V2L to compensate for instantaneous fluctuations in PV power caused by factors such as cloud cover in real time, maintaining the stability of the total charging power of the energy storage system. This eliminates the problem of sudden changes in charging current during PV power drops caused by insufficient response speed in existing solutions.

[0026] The present invention adopts the following technical solution.

[0027] A charging control method for a photovoltaic (PV) and vehicle-to-everything (V2L) energy storage system is disclosed. This method, for the first time, defines the V2L provided by the electric vehicle battery as a real-time compensation source for PV power fluctuations, forming a unified collaborative control closed loop with the PV input source. Its core design concept lies in utilizing the millisecond-level fast response characteristics of V2L to compensate for instantaneous fluctuations in PV power caused by factors such as cloud cover, maintaining the stability of the total charging power of the energy storage system. This eliminates the problem of sudden charging current changes during PV power drops caused by insufficient response speed in existing solutions. The method first assesses PV power fluctuations using the maximum available PV power and the PV power change rate. If the fluctuation amplitude reaches a compensation threshold, it automatically calculates the power deficit and immediately increases the discharge power of V2L to compensate for the deficit, maintaining the stability of the total charging power of the energy storage battery in the energy storage system.

[0028] The V2L response speed is superior to grid dispatch, and it provides millisecond-level compensation to the energy storage system with a millisecond-level response speed. This fundamentally solves the technical problem of the mismatch between the response time scale (hundreds of milliseconds to seconds) of existing energy storage batteries and grid dispatch schemes and the time scale of photovoltaic fluctuations (milliseconds).

[0029] The control method includes the following steps;

[0030] Step 1: Track the maximum power point of the photovoltaic panel in real time using the MPPT algorithm to obtain the current maximum available photovoltaic power, and continuously monitor the output voltage and output current of the photovoltaic panel at a preset sampling period;

[0031] Step 2: The charging control system of the photovoltaic and V2L collaborative energy storage system calculates the rate of change of photovoltaic power in real time. When the absolute value of the rate of change of photovoltaic power exceeds the preset fluctuation threshold, it is determined that the photovoltaic power has fluctuated significantly and reached the threshold that needs to be compensated.

[0032] Step 3: When a decrease in photovoltaic power is detected, the system automatically calculates the power deficit and immediately increases the discharge power of V2L to compensate for the deficit and maintain the stability of the total charging power of the energy storage battery.

[0033] Step 4: The photovoltaic and V2L collaborative energy storage system limits the total input power of photovoltaic and V2L based on the maximum allowable charging power of the energy storage battery to avoid power surges impacting the energy storage system. Specifically, when the total power exceeds the maximum allowable charging power, the discharge power of V2L is reduced first to protect the vehicle battery, and then the input power of photovoltaic is reduced. When the photovoltaic power recovers, the system automatically reduces the discharge power of V2L and returns the charging power share to the photovoltaic input source. The recovery rate of V2L discharge power matches the recovery rate of photovoltaic power.

[0034] A charging control system for a photovoltaic (PV) and V2L (Vehicle-to-Lane) collaborative energy storage system, using the aforementioned PV and V2L collaborative energy storage system charging control method, is characterized in that: the energy storage system is an energy storage system comprising a PV input source and a V2L mobile input source, including: a PV array, an MPPT controller (integrated with an energy storage converter or as an independent module), an energy storage battery pack, a battery management system (BMS), a V2L access interface (supporting V2L discharge gun access for electric vehicles), a main control MCU (STM32F4 series or GD32F4 series Cortex-M4 processor recommended), and a communication bus connecting the above units, wherein the communication bus includes a CAN bus and an I2C bus;

[0035] In the charging control system, the main control MCU communicates with the BMS via the CAN bus to obtain battery status parameters, communicates with the MPPT controller via the I2C bus or PWM signal to achieve maximum power point tracking control, and communicates with the V2L access interface via the I2C bus to obtain vehicle battery parameters and control V2L discharge power.

[0036] When the charging control system is working, the V2L mobile input source formed by the electric vehicle is connected to the energy storage system through the AC charging interface. Different brands and models of electric vehicles (EVs) have different V2L discharge powers (covering the range of 2.2kW to 6kW), and their discharge conditions (P gear, power-on, lower SOC limit, etc.) also differ. The charging control system achieves compatibility and adaptation for different vehicle models through a collaborative control method: the collaborative control method includes the following steps;

[0037] Step S1: When the user inserts the V2L discharge gun of the electric vehicle into the AC input port of the energy storage system, the V2L access detection unit first detects the physical connection status of the V2L device, confirms that the discharge gun has established a reliable connection with the vehicle, and that the vehicle has started the inverter and begun to output AC power.

[0038] Step S2: The charging control system, in accordance with the IEC 61851-1 standard, communicates with the vehicle control unit (VCU) through the control guidance signal CP and the proximity guidance signal PP to establish a handshake connection and complete the function configuration, so that the vehicle can start supplying power to the energy storage system.

[0039] Step S3: After a successful handshake, the system obtains vehicle battery parameters via standard communication protocols (IEC 61851 series, ISO 15118, etc.), including vehicle battery type (such as lithium iron phosphate, ternary lithium, etc.), nominal voltage and capacity, current state of charge (SOC), current state of battery health (SOH), and maximum V2L output power.

[0040] And the user-defined expected stay duration;

[0041] Step S4: The system reads... The V2L target discharge power is limited to ensure it does not exceed the vehicle's capacity; simultaneously, the vehicle's SOC is monitored in real time. (Reserved threshold, recommended 15%-25%) Stop V2L discharge, and work in conjunction with the vehicle's own SOC protection mechanism (most models force a stop discharge when SOC is below 20%).

[0042] In this invention, the superscript EV of each parameter represents the relevant parameters of an electric vehicle, and the superscript PV represents the relevant parameters of a photovoltaic system.

[0043] In the aforementioned collaborative control method, the charging control system simultaneously applies battery-friendly discharge constraints to the vehicle battery. These constraints include a maximum depth of discharge limit based on the vehicle battery's State of Health (SOH), a discharge power limit based on the vehicle battery's State of Charge (SOC), and a return trip charge reserve threshold. This ensures that V2L discharge does not cause additional damage to the vehicle battery's lifespan. The system also continuously monitors the operating status of the V2L device. When the vehicle battery temperature exceeds a preset safety threshold or the V2L device is physically disconnected, the system automatically switches to photovoltaic single-input charging mode to ensure safe system operation.

[0044] In step one, the charging control system uses the MPPT algorithm to track the maximum power point of the photovoltaic panel in real time to obtain the current maximum photovoltaic power. The core of the MPPT algorithm lies in adjusting the output voltage of the photovoltaic panel to ensure it always operates at the peak point of the power-voltage (PV) characteristic curve. The MPPT algorithm is recommended to use either the perturbation-observation method or the incremental conductance method.

[0045] When using the perturbation-observation method, the charging control system continuously acquires the output voltage of the photovoltaic panel at a preset sampling period (10ms-100ms recommended). and output current Calculate the current output power ;

[0046] In each control cycle, the charging control system algorithm applies a small perturbation to the operating voltage of the photovoltaic panel and observes the direction of power change. If the power increases, the perturbation continues in the same direction; if the power decreases, the perturbation is reversed. Through the iterative process of perturbation, observation, and adjustment, the system gradually approaches the maximum power point and operates stably near the maximum power point.

[0047] When the charging control system detects that the current environment is in a scenario of rapid changes in light (such as cloudy weather), the system switches to the incremental conductance method. This method determines the relative position of the maximum power point by comparing the instantaneous conductance with the amount of conductance change, which can track changes in light more quickly and reduce power loss.

[0048] The charging control system uses the maximum power point voltage it tracks as the target reference voltage for the MPPT controller and outputs it to the subsequent DC-DC converter, so that the photovoltaic panel always operates near the maximum power point.

[0049] In step two, based on obtaining the current maximum available photovoltaic power, the charging control system needs to continuously monitor the real-time changes in photovoltaic power to determine whether V2L collaborative compensation needs to be triggered or compensation needs to be withdrawn. If the photovoltaic output power is significantly intermittent and fluctuating due to the influence of sunlight conditions, when cloud cover causes a sudden drop in photovoltaic power, the charging control system must respond within a millisecond timescale and initiate V2L compensation to maintain the stability of the total charging power. When sunlight recovers, the charging control system must also withdraw compensation in a timely manner, return the charging power share to the photovoltaic input source, and use the photovoltaic power fluctuation detection mechanism as a triggering basis for control decisions.

[0050] The photovoltaic power fluctuation detection mechanism is as follows:

[0051] The charging control system calculates the rate of change of photovoltaic power in real time:

[0052]

[0053] in This represents the real-time output power of the photovoltaic panel. The recommended detection period is 10ms-100ms. The selection of this period should balance detection sensitivity and system stability. A shorter period results in more sensitive detection but is more susceptible to noise interference; a longer period provides stronger anti-interference capabilities but increases response delay. The recommended default value is 50ms, which can be optimized and adjusted during the commissioning phase based on ambient lighting conditions and system noise levels.

[0054] when When the absolute value exceeds the preset fluctuation threshold, the charging control system determines that the photovoltaic power has fluctuated significantly.

[0055] The fluctuation threshold is based on the photovoltaic rated power. Based on this, it is recommended to set it to to The specific value can be dynamically adjusted according to weather conditions. Under sunny weather conditions, the light intensity is stable, so the threshold can be appropriately increased to avoid frequent triggering of compensation due to slight fluctuations. Under cloudy weather conditions, the light intensity changes drastically, so the threshold can be appropriately decreased to improve the compensation sensitivity and ensure a rapid response.

[0056] The system according to Pattern determination is performed based on the sign and amplitude:

[0057] when Furthermore, when its absolute value exceeds the fluctuation threshold, it indicates a significant decrease in photovoltaic power, and the system immediately enters the V2L collaborative compensation mode.

[0058] when Furthermore, when its amplitude exceeds the fluctuation threshold, and the photovoltaic power shows a continuous recovery trend, that is, within multiple consecutive detection cycles... The system determines that the photovoltaic power has been restored and enters the V2L power return process (called automatic callback), which gradually reduces the V2L discharge power and transfers the charging power share back to the photovoltaic input source;

[0059] To avoid frequent fluctuations in photovoltaic power around the threshold, which would cause frequent adjustments to V2L discharge power, a hysteresis range is introduced for fluctuation detection. When the change in photovoltaic power exceeds the threshold, it must fall back to a preset percentage below the threshold (50% of the threshold is recommended) before exiting the current mode, ensuring the stability of mode switching.

[0060] In step three, the V2L collaborative compensation mode is used for V2L collaborative compensation and power distribution optimization. Its core control logic is as follows: First, the charging control system calculates the power deficit and increases the V2L discharge power in real time to fill the gap caused by the decrease in photovoltaic power; Second, when photovoltaic and V2L supply power to the energy storage battery at the same time, the charging control system limits the total input power and optimizes the distribution among the input sources. While giving priority to the use of photovoltaic energy, it minimizes the V2L discharge of the electric vehicle to protect the vehicle battery.

[0061] The V2L collaborative compensation mechanism in the V2L collaborative compensation model is as follows:

[0062] When the charging control system detects a decrease in photovoltaic power, it automatically calculates the power deficit using the following formula:

[0063]

[0064] in The target power of the photovoltaic system (i.e., the value sampled just before the moment of decrease). This represents the current actual photovoltaic power output.

[0065] The charging control system automatically increases the discharge power of V2L to compensate for the power deficit of photovoltaic power, thereby maintaining a stable total charging power of the energy storage battery. The formula is as follows:

[0066]

[0067] in This represents the current discharge power of V2L. The target discharge power for V2L;

[0068] Upon detecting a drop in photovoltaic power, the system sends a power dispatch command to the V2L device within 50ms, and the V2L completes power ramp-up within 100ms. The millisecond-level response speed of V2L is far superior to grid dispatch (seconds to minutes), enabling real-time compensation for sudden drops in photovoltaic power.

[0069] After V2L collaborative compensation control is activated, both photovoltaic and V2L input sources simultaneously supply power to the energy storage battery, with the total input power being the sum of the two. The charging control system performs total power limiting and allocation optimization, prioritizing the use of photovoltaic energy while minimizing V2L discharge to protect the vehicle battery, provided that charging demand is met. Specifically, to prevent the total power from exceeding the maximum allowable charging capacity of the energy storage battery, the charging control system limits the total power and optimizes the power allocation of each input source during the limiting process.

[0070] In step four, the charging control system determines the maximum allowable charging power of the energy storage battery. (Calculated and reported in real time by BMS) The total input power of photovoltaic and V2L is limited;

[0071] The power allocation of each input source follows the following priority rules: photovoltaic input source first (green energy, zero cost), V2L mobile input source second (as a compensation source, but constrained by vehicle battery life), and grid input source last (as a backup, highest cost).

[0072] Under this priority framework, the total power after limiting satisfies:

[0073]

[0074] when When the battery's state of charge (SOC) is close to full charge, the charging control system proportionally reduces the total input power, prioritizing the reduction of V2L discharge power to avoid overcharging.

[0075] The V2L power recovery process is as follows: After the photovoltaic power fluctuation detection unit determines that the photovoltaic power has dropped significantly, the charging control system must initiate a compensation action within a millisecond time scale to maintain the stability of the total charging power of the energy storage battery; if the response speed of the energy storage battery and the grid dispatch cannot match the millisecond time scale of the photovoltaic power drop, the charging control system calls the V2L mobile input source as a compensation source, and uses its millisecond-level fast response characteristics to immediately increase the discharge power to fill the gap caused by the drop in photovoltaic power.

[0076] In step four, when the photovoltaic power recovers, the charging control system automatically reduces the V2L discharge power, returning a portion of the charging power to the photovoltaic input source. The V2L discharge power recovery rate is matched with the photovoltaic power recovery rate. Specifically, the V2L discharge power recovery rate is set as follows: According to the photovoltaic power recovery rate Dynamically determined:

[0077]

[0078] in The maximum V2L callback rate is preset (recommended to be 10%-20% of the rated power per second) to avoid the impact of power sudden changes on the V2L system. The charging control system detects the photovoltaic power recovery status with a preset period of 100ms and adjusts the V2L discharge power periodically until the V2L discharge power returns to zero or the photovoltaic power recovers to the target value, thus realizing a smooth power transfer from V2L to photovoltaic.

[0079] The charging control system applies battery-friendly V2L discharge constraints to electric vehicles participating in photovoltaic and V2L collaboration. Specifically, during V2L collaborative compensation, the charging control system utilizes the energy from the vehicle's battery to fill the gap caused by the decrease in photovoltaic power. However, V2L discharge essentially consumes the cycle life of the vehicle's battery. Frequent deep discharges or high-power discharges accelerate battery aging, leading to degradation of the cathode material structure, increased lithium-ion loss, and a significantly increased capacity decay rate. Therefore, when utilizing V2L for power compensation, the charging control system must simultaneously apply discharge constraints to the vehicle's battery to balance the compensation demand with battery life protection. Battery-friendly discharge constraints are the specific implementation of the aforementioned life protection mechanism.

[0080] The charging control system applies the following constraints based on the vehicle battery's SOH (State of Health, i.e., the percentage of current battery capacity relative to the factory rated capacity, reflecting the degree of battery aging) and current SOC (State of Charge, i.e., the percentage of current remaining capacity relative to the full charge capacity):

[0081] A1. Maximum Depth of Discharge Limit Based on State of Harmony (SOH): SOH is a core indicator for measuring battery aging. A lower SOH indicates higher internal resistance and greater loss of active materials, meaning deeper discharge causes more significant damage to aging batteries. The system determines the recommended maximum depth of discharge under the current SOH based on the vehicle battery's cycle life curve. When the SOH is below 80%, it indicates that the battery has entered the accelerated aging stage. The system automatically reduces the maximum allowable depth of discharge and limits the energy release ratio of the battery in each discharge cycle in order to slow down the aging process.

[0082] A2. Discharge power limitation based on SOC: SOC reflects the battery's currently available remaining energy. The system calculates the recommended maximum discharge power based on the vehicle battery's current SOC. The lower the State of Charge (SOC), the less usable energy the battery has. If high-power discharge is performed at this level, the battery voltage will rapidly drop below the cutoff voltage, potentially triggering the vehicle's Battery Management System (BMS) protection mechanism and forcibly interrupting the discharge. Therefore, the system limits the discharge power as the SOC decreases to avoid high-power discharge in the low SOC range.

[0083] A3. Return Trip Battery Reserve Threshold: The system reserves the required battery power for the return trip based on the vehicle's destination information or the user's settings. This mechanism ensures that V2L discharge only consumes the "surplus" charge in the vehicle's battery, i.e. The corresponding power, of which

[0084] This is the current battery level. To meet the minimum power threshold required for the return trip, without depleting the energy reserves needed to ensure normal vehicle operation, thus preventing the vehicle from being unable to reach its destination due to V2L discharge.

[0085] Based on the above constraints, the system generates a battery-friendly discharge curve to control the discharge power, so that the discharge power gradually decreases as the SOC decreases.

[0086] The charging control system also performs V2L discharge state monitoring and protection to ensure that the system can safely exit the compensation state under any abnormal conditions. Specifically, the control process described above establishes a complete forward control link from photovoltaic fluctuation detection, V2L compensation initiation, power limiting to discharge constraint. However, the V2L discharge process involves real-time interaction between the energy storage system and external devices (electric vehicles). The temperature, SOC, and physical connection status of the vehicle battery and V2L devices may change at any time during the discharge process. These changes are not triggered by the energy storage system's control strategy but are uncontrolled changes caused by external factors (such as changes in ambient temperature, actual vehicle driving needs, user plugging and unplugging operations, etc.), and cannot be predicted and avoided through the forward control link described above. Therefore, the system needs to add an independent discharge state monitoring and protection mechanism on the basis of the above control link to cope with unpredictable state changes of external devices and ensure that the system can safely exit the compensation state under any abnormal conditions. V2L discharge state monitoring and protection is the aforementioned safety fallback mechanism. The system continuously monitors the output voltage, output current, vehicle SOC, and battery temperature of the V2L device at preset intervals (1 to 10 seconds recommended). When the following abnormal states are detected, the system executes corresponding protection actions:

[0087] B1. When the vehicle battery temperature exceeds the preset safety threshold, the system immediately stops V2L discharge and switches to photovoltaic single-input charging mode. Battery temperature is a critical boundary condition for the safe operation of lithium-ion batteries. Excessive temperature will accelerate the degradation of the positive electrode material structure and the thermal shrinkage of the separator, which may lead to thermal runaway in severe cases. Therefore, this protection action has the highest priority and is executed unconditionally.

[0088] B2. When the vehicle's State of Charge (SOC) falls below the minimum threshold reserved for the return trip, the system automatically reduces the V2L discharge power until it stops. This ensures that V2L discharge does not cause the vehicle's SOC to drop below the minimum charge threshold for guaranteed driving, thus preventing the vehicle from being unable to reach its destination due to V2L discharge.

[0089] When B3 and V2L devices are physically disconnected, the system detects the disconnection signal within 50ms and immediately shuts down the V2L input channel, switching to photovoltaic single-input charging mode or standby mode. This protection ensures the system can respond quickly when external equipment is unexpectedly disconnected, avoiding abnormal bus voltage caused by power loop open circuits.

[0090] The three protection actions mentioned above correspond to three different abnormal triggering conditions: abnormal battery temperature triggers unconditional shutdown, low SOC triggers gradual power reduction until shutdown, and physical disconnection of equipment triggers rapid channel shutdown. The response strategies of the three protections are matched with the urgency of the triggering conditions, together forming a complete V2L discharge safety protection chain.

[0091] The charging control system also performs dynamic adjustment and smoothing control of V2L discharge power. Specifically, the control flow described above (sections 3.1 to 3.4) establishes a complete control link from photovoltaic fluctuation detection, compensation initiation, power limiting to discharge constraints. This link ensures that V2L can quickly and accurately initiate compensation and apply necessary power limiting and battery protection constraints when photovoltaic power drops sharply. However, in the above control link, the command value of V2L discharge power may jump due to rapid fluctuations in photovoltaic power or detection noise. If the rate of change of these power commands is not limited, the vehicle battery will be frequently subjected to current surges, accelerating its aging. In addition, if the photovoltaic power frequently crosses the fluctuation detection threshold, it will cause frequent start-stop or large adjustment of V2L power, further aggravating system oscillation.

[0092] Therefore, during V2L discharge, the system also needs to smooth the changes in power command to eliminate the non-ideal factors at the control level. The dynamic adjustment and smoothing control mechanism described above is the specific implementation of this smoothing process. The system dynamically adjusts the V2L discharge power based on photovoltaic power fluctuations and changes in the SOC of the energy storage battery. To smooth the control process, the system employs the following mechanism:

[0093] C1. Power Change Rate Limitation: The rate of change of V2L discharge power shall not exceed the preset maximum rate of change (recommended to be 20% of rated power per second) to avoid sudden power surges impacting the vehicle battery and energy storage system. This mechanism directly limits the transient rate of power command and is the first line of defense for smooth control.

[0094] C2. Hysteresis Control: A hysteresis range (recommended 5% of rated power) is set in the photovoltaic power fluctuation detection to prevent frequent fluctuations in photovoltaic power near the threshold, which would cause frequent adjustments to the V2L discharge power. This mechanism prevents the system from repeatedly switching states near the detection threshold, serving as the second line of defense for smooth control.

[0095] C3. Filtering: The photovoltaic power sampling value is low-pass filtered (cutoff frequency recommended to be 10Hz) to remove high-frequency noise and avoid V2L malfunctions caused by sampling noise. This mechanism eliminates high-frequency disturbances in the input signal and is the third line of defense for smooth control.

[0096] The three mechanisms described above suppress abrupt changes in power command from different levels. The rate of change limit directly constrains the rate of power change, hysteresis control eliminates the back-and-forth switching near the threshold, and filtering removes noise components from the input signal. Working together, these three mechanisms ensure the smoothness and stability of V2L discharge power from the dimensions of "output rate of change," "state switching frequency," and "input signal quality," respectively, forming a complete power smoothing control chain.

[0097] This invention achieves deep synergy between photovoltaic MPPT and V2L input. Photovoltaics provides green energy as the main input, while V2L serves as a real-time compensation source for photovoltaic fluctuations. The two achieve millisecond-level dynamic power allocation through a unified collaborative control framework. Compared with the existing technology where photovoltaics and V2L work independently and photovoltaic-V2L collaboration is concentrated in grid-level energy management, this invention focuses on real-time compensation for photovoltaic fluctuations during the charging process of the energy storage system. It has fundamental differences in control objectives, response speed, and collaborative mechanisms, and has significant advantages.

[0098] This invention can solve the following technical problems:

[0099] (1) Utilizing the millisecond-level fast response characteristics of V2L, real-time compensation for photovoltaic power fluctuations is achieved, so that the total charging power of the energy storage system remains stable when the photovoltaic power drops sharply, thus avoiding the impact of sudden changes in charging current on battery life.

[0100] (2) Redefine V2L from an independent load power supply to a real-time compensation source for photovoltaic fluctuations, and establish a unified collaborative control framework for photovoltaic MPPT and V2L input, so that V2L can automatically adjust its discharge power according to the changes in photovoltaic power.

[0101] (3) Under the premise of ensuring the stability of total charging power, the power ratio of photovoltaic and V2L should be reasonably allocated. During the V2L collaborative compensation process, vehicle battery friendly discharge constraints should be applied at the same time to give priority to photovoltaic energy and reduce the loss of vehicle battery by V2L discharge.

[0102] (4) When the photovoltaic power recovers, the charging power share is automatically returned to the photovoltaic input source to maximize the utilization rate of green energy.

[0103] The comparison between the present invention and the prior art is presented in the table below:

[0104]

[0105] This invention offers several advantages over existing technologies, encompassing improved response speed, V2L role reconfiguration, focused control objectives, innovative collaborative mechanisms, and engineering feasibility. These advantages stem from the synergistic effect between the photovoltaic and V2L collaborative energy storage system charging control method proposed in this invention, and its supporting collaborative scheduling mechanism, power limiting mechanism, and battery-friendly discharge constraint mechanism. The overall technical effect is the result of the organic combination of these various technical features, including the following aspects:

[0106] First, it can achieve millisecond-level response speed to realize real-time compensation for photovoltaic fluctuations.

[0107] This invention defines V2L (Vehicle-to-Lake) as a real-time compensation source for photovoltaic power fluctuations for the first time. Utilizing the millisecond-level rapid response characteristics of V2L, it achieves real-time compensation for sudden drops in photovoltaic power. In existing technologies, the response speed of energy storage batteries is limited by BMS communication delays and the dynamic characteristics of the batteries themselves, typically requiring hundreds of milliseconds to several seconds to complete power adjustments; grid dispatch response speeds range from seconds to minutes. However, the V2L in this invention achieves a millisecond-level response speed—the system issues a power dispatch command within 50ms, and V2L completes power ramp-up within 100ms, fundamentally solving the technical problem of the mismatch between the response timescale (hundreds of milliseconds to seconds) of existing solutions and the photovoltaic fluctuation timescale (milliseconds).

[0108] Second, it can reshape the role of V2L and fill the functional gaps in existing technologies.

[0109] In existing technologies, the role of V2L (Vehicle-to-Land) is limited to the power supply end of the load, that is, V2L outputs power to loads such as household appliances and outdoor equipment. Although solar V2L schemes in academic research involve photovoltaics charging electric vehicles, and the electric vehicles then supply power to loads through V2L, the energy transfer relationship between photovoltaics and V2L is series-connected, lacking a real-time coordinated control mechanism. This invention redefines V2L for the first time from "independent load power supply" to "real-time compensation source for photovoltaic power fluctuations," extending the millisecond-level fast response characteristics of V2L from "meeting only the load power supply needs" to "real-time compensation for photovoltaic fluctuations," filling the functional gap in existing technologies for using V2L for photovoltaic fluctuation compensation.

[0110] Third, it can focus on the charging process of the energy storage system and achieve millisecond-level "rapid change" compensation.

[0111] Existing photovoltaic-V2L collaborative solutions focus on the grid or household load level for control objectives. In integrated photovoltaic-storage-charging control schemes and photovoltaic power generation-V2H collaborative control schemes, the V2L / V2H control objective is energy balance and power dispatch at the household load power supply or microgrid level, with response time scales ranging from seconds to minutes, addressing the problem of "slow changes." This invention focuses on real-time fluctuation compensation of photovoltaic power during the charging process of an energy storage system, addressing the problem of "fast changes" within a millisecond time scale. It differs fundamentally from existing technologies in both control objectives (real-time compensation vs. energy optimization) and response speed (milliseconds vs. seconds to minutes).

[0112] Fourth, it can establish a unified and coordinated control closed loop between photovoltaic MPPT and V2L, and realize closed-loop dynamic compensation.

[0113] Existing multi-source collaborative power control schemes utilize multi-source power supply modules including a three-phase AC grid, photovoltaic modules, and energy storage modules, but do not involve V2L (vehicle-to-everything) mobile input sources. Their power allocation strategies are based on preset power supply mode decision-making strategies, which are open-loop, rule-based decisions. The photovoltaic MPPT controller and V2L operate independently; the MPPT controller only tracks the photovoltaic maximum power point, and the V2L only responds to the load's power demand. There is no information exchange or collaborative control between them. This invention establishes a unified collaborative control closed loop for the photovoltaic MPPT and V2L inputs, enabling the V2L to automatically adjust its discharge power based on real-time fluctuations in photovoltaic power, achieving a paradigm shift from "open-loop rule-based decision-making" to "closed-loop dynamic compensation."

[0114] Fifth, it can achieve a combination of battery-friendly discharge constraint and collaborative control, balancing compensation effect and battery life.

[0115] This invention applies battery-friendly discharge constraints to the vehicle battery simultaneously during V2L collaborative compensation, including a maximum depth of discharge limit based on State of Health (SOH), a discharge power limit based on State of Charge (SOC), and a return trip charge reserve threshold. This ensures that V2L discharge does not cause additional damage to the vehicle battery's lifespan. This mechanism enables the system to achieve real-time compensation for photovoltaic fluctuations while also protecting the vehicle battery's lifespan, avoiding the problem of accelerated battery aging caused by frequent deep discharges during V2L.

[0116] Sixth, it can achieve automatic power return when photovoltaic power is restored, maximizing the utilization rate of green energy.

[0117] This invention automatically reduces V2L discharge power when photovoltaic power recovers, returning a portion of the charging power to the photovoltaic input source. The V2L discharge power recovery rate matches the photovoltaic power recovery rate, preventing sudden power fluctuations from impacting the energy storage system. This mechanism ensures priority utilization of photovoltaic energy. When photovoltaic power becomes available, V2L automatically exits compensation, returning a portion of the charging power to the photovoltaic system, maximizing the utilization rate of green energy and reducing reliance on vehicle batteries.

[0118] Seventh, the project is easy to implement and has broad application prospects.

[0119] This invention is primarily implemented through software algorithms and can be deployed in the main control MCU of an energy storage system without requiring hardware modifications to the electric vehicle. With the rapid adoption of V2L technology in new electric vehicles, this invention provides a systematic control method for utilizing the electric vehicle's power battery as a real-time compensation source for photovoltaic fluctuations. This invention can be widely applied to various energy storage systems that include both photovoltaic and V2L inputs, including portable energy storage power supplies, home energy storage systems, outdoor power supplies, and integrated photovoltaic-storage-charging systems, demonstrating broad industrial application prospects and commercial value.

[0120] Eighth, expand the off-grid application value of V2L technology.

[0121] Existing V2L technology can directly power household appliances, but it is limited by vehicle discharge power and battery SOC, failing to meet the off-grid power demands of high-power, long-term, and multi-load applications. This invention, by coordinating V2L with photovoltaic (PV) and energy storage systems, constructs a collaborative architecture where PV serves as the primary power source, energy storage acts as an intermediate buffer, and V2L provides real-time compensation. Utilizing the energy storage system as an intermediary for power buffering and energy time-shifting, the application scenarios of V2L are expanded from directly powering loads to collaborating with PV to supplement the energy storage system, and then using the energy storage system to stabilize power supply. This significantly enhances the practical value of V2L technology in off-grid scenarios such as outdoor camping and emergency power supply. Specifically, PV provides green energy as the primary input, energy storage smooths power fluctuations and achieves energy time-shifting, and V2L serves as a real-time compensation source for PV fluctuations. These three elements complement and coordinate to form a complete off-grid power supply system. With the rapid adoption of V2L technology in new electric vehicles, this invention provides a systematic control method for utilizing electric vehicle batteries as supplementary energy for off-grid power supply.

[0122] This invention can greatly improve the reliability of photovoltaic power supply to the energy storage system of electric vehicle charging stations. When electric vehicles need to be parked for a long time while charging at electric vehicle charging stations with photovoltaic power supply, the vehicle owner can actively choose whether to participate in the operation of the charging station energy storage system by actively discharging the vehicle for a fee. On the one hand, it provides stability for photovoltaic power supply to charging stations, and on the other hand, it provides vehicle owners with a revenue channel to earn additional income from electric vehicles. Attached Figure Description

[0123] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0124] Appendix Figure 1 This is a schematic diagram of the system architecture of the charging control system of the photovoltaic and V2L collaborative energy storage system in an embodiment of the present invention;

[0125] Appendix Figure 2 This is a schematic diagram of the V2L fast compensation timing during a sudden drop in photovoltaic power, as described in this embodiment of the invention.

[0126] Appendix Figure 3 This is a schematic diagram of the V2L automatic callback timing when photovoltaic power is restored in an embodiment of the present invention. Detailed Implementation

[0127] As shown in the figure, a charging control method for a photovoltaic (PV) and V2L (Vehicle-to-Lane) collaborative energy storage system is presented. This method, for the first time, defines the V2L provided by the electric vehicle battery as a real-time compensation source for PV power fluctuations, forming a unified collaborative control closed loop with the PV input source. Its core design concept lies in utilizing the millisecond-level fast response characteristics of V2L to compensate for instantaneous fluctuations in PV power caused by factors such as cloud cover in real time, maintaining the stability of the total charging power of the energy storage system. This eliminates the problem of sudden changes in charging current during PV power drops caused by insufficient response speed in existing solutions. The method first assesses PV power fluctuations using the maximum available PV power and the PV power change rate. If the fluctuation amplitude reaches the compensation threshold, it automatically calculates the power deficit and immediately increases the discharge power of V2L to compensate for the deficit, maintaining the stability of the total charging power of the energy storage battery in the energy storage system.

[0128] The V2L response speed is superior to grid dispatch, and it provides millisecond-level compensation to the energy storage system with a millisecond-level response speed. This fundamentally solves the technical problem of the mismatch between the response time scale (hundreds of milliseconds to seconds) of existing energy storage batteries and grid dispatch schemes and the time scale of photovoltaic fluctuations (milliseconds).

[0129] The control method includes the following steps;

[0130] Step 1: Track the maximum power point of the photovoltaic panel in real time using the MPPT algorithm to obtain the current maximum available photovoltaic power, and continuously monitor the output voltage and output current of the photovoltaic panel at a preset sampling period;

[0131] Step 2: The charging control system of the photovoltaic and V2L collaborative energy storage system calculates the rate of change of photovoltaic power in real time. When the absolute value of the rate of change of photovoltaic power exceeds the preset fluctuation threshold, it is determined that the photovoltaic power has fluctuated significantly and reached the threshold that needs to be compensated.

[0132] Step 3: When a decrease in photovoltaic power is detected, the system automatically calculates the power deficit and immediately increases the discharge power of V2L to compensate for the deficit and maintain the stability of the total charging power of the energy storage battery.

[0133] Step 4: The photovoltaic and V2L collaborative energy storage system limits the total input power of photovoltaic and V2L based on the maximum allowable charging power of the energy storage battery to avoid power surges impacting the energy storage system. Specifically, when the total power exceeds the maximum allowable charging power, the discharge power of V2L is reduced first to protect the vehicle battery, and then the input power of photovoltaic is reduced. When the photovoltaic power recovers, the system automatically reduces the discharge power of V2L and returns the charging power share to the photovoltaic input source. The recovery rate of V2L discharge power matches the recovery rate of photovoltaic power.

[0134] A charging control system for a photovoltaic (PV) and V2L (Vehicle-to-Lane) collaborative energy storage system, using the aforementioned PV and V2L collaborative energy storage system charging control method, is characterized in that: the energy storage system is an energy storage system comprising a PV input source and a V2L mobile input source, including: a PV array, an MPPT controller (integrated with an energy storage converter or as an independent module), an energy storage battery pack, a battery management system (BMS), a V2L access interface (supporting V2L discharge gun access for electric vehicles), a main control MCU (STM32F4 series or GD32F4 series Cortex-M4 processor recommended), and a communication bus connecting the above units, wherein the communication bus includes a CAN bus and an I2C bus;

[0135] In the charging control system, the main control MCU communicates with the BMS via the CAN bus to obtain battery status parameters, communicates with the MPPT controller via the I2C bus or PWM signal to achieve maximum power point tracking control, and communicates with the V2L access interface via the I2C bus to obtain vehicle battery parameters and control V2L discharge power.

[0136] When the charging control system is working, the V2L mobile input source formed by the electric vehicle is connected to the energy storage system through the AC charging interface. Different brands and models of electric vehicles (EVs) have different V2L discharge powers (covering the range of 2.2kW to 6kW), and their discharge conditions (P gear, power-on, lower SOC limit, etc.) also differ. The charging control system achieves compatibility and adaptation for different vehicle models through a collaborative control method: the collaborative control method includes the following steps;

[0137] Step S1: When the user inserts the V2L discharge gun of the electric vehicle into the AC input port of the energy storage system, the V2L access detection unit first detects the physical connection status of the V2L device, confirms that the discharge gun has established a reliable connection with the vehicle, and that the vehicle has started the inverter and begun to output AC power.

[0138] Step S2: The charging control system, in accordance with the IEC 61851-1 standard, communicates with the vehicle control unit (VCU) through the control guidance signal CP and the proximity guidance signal PP to establish a handshake connection and complete the function configuration, so that the vehicle can start supplying power to the energy storage system.

[0139] Step S3: After a successful handshake, the system obtains vehicle battery parameters via standard communication protocols (IEC 61851 series, ISO 15118, etc.), including vehicle battery type (such as lithium iron phosphate, ternary lithium, etc.), nominal voltage and capacity, current state of charge (SOC), current state of battery health (SOH), and maximum V2L output power.

[0140] And the user-defined expected stay duration;

[0141] Step S4: The system reads... The V2L target discharge power is limited to ensure it does not exceed the vehicle's capacity; simultaneously, the vehicle's SOC is monitored in real time. (Reserved threshold, recommended 15%-25%) Stop V2L discharge, and work in conjunction with the vehicle's own SOC protection mechanism (most models force a stop discharge when SOC is below 20%).

[0142] In this invention, the superscript EV of each parameter represents the relevant parameters of an electric vehicle, and the superscript PV represents the relevant parameters of a photovoltaic system.

[0143] In the aforementioned collaborative control method, the charging control system simultaneously applies battery-friendly discharge constraints to the vehicle battery. These constraints include a maximum depth of discharge limit based on the vehicle battery's State of Health (SOH), a discharge power limit based on the vehicle battery's State of Charge (SOC), and a return trip charge reserve threshold. This ensures that V2L discharge does not cause additional damage to the vehicle battery's lifespan. The system also continuously monitors the operating status of the V2L device. When the vehicle battery temperature exceeds a preset safety threshold or the V2L device is physically disconnected, the system automatically switches to photovoltaic single-input charging mode to ensure safe system operation.

[0144] In step one, the charging control system uses the MPPT algorithm to track the maximum power point of the photovoltaic panel in real time to obtain the current maximum photovoltaic power. The core of the MPPT algorithm lies in adjusting the output voltage of the photovoltaic panel to ensure it always operates at the peak point of the power-voltage (PV) characteristic curve. The MPPT algorithm is recommended to use either the perturbation-observation method or the incremental conductance method.

[0145] When using the perturbation-observation method, the charging control system continuously acquires the output voltage of the photovoltaic panel at a preset sampling period (10ms-100ms recommended). and output current Calculate the current output power ;

[0146] In each control cycle, the charging control system algorithm applies a small perturbation to the operating voltage of the photovoltaic panel and observes the direction of power change. If the power increases, the perturbation continues in the same direction; if the power decreases, the perturbation is reversed. Through the iterative process of perturbation, observation, and adjustment, the system gradually approaches the maximum power point and operates stably near the maximum power point.

[0147] When the charging control system detects that the current environment is in a scenario of rapid changes in light (such as cloudy weather), the system switches to the incremental conductance method. This method determines the relative position of the maximum power point by comparing the instantaneous conductance with the amount of conductance change, which can track changes in light more quickly and reduce power loss.

[0148] The charging control system uses the maximum power point voltage it tracks as the target reference voltage for the MPPT controller and outputs it to the subsequent DC-DC converter, so that the photovoltaic panel always operates near the maximum power point.

[0149] In step two, based on obtaining the current maximum available photovoltaic power, the charging control system needs to continuously monitor the real-time changes in photovoltaic power to determine whether V2L collaborative compensation needs to be triggered or compensation needs to be withdrawn. If the photovoltaic output power is significantly intermittent and fluctuating due to the influence of sunlight conditions, when cloud cover causes a sudden drop in photovoltaic power, the charging control system must respond within a millisecond timescale and initiate V2L compensation to maintain the stability of the total charging power. When sunlight recovers, the charging control system must also withdraw compensation in a timely manner, return the charging power share to the photovoltaic input source, and use the photovoltaic power fluctuation detection mechanism as a triggering basis for control decisions.

[0150] The photovoltaic power fluctuation detection mechanism is as follows:

[0151] The charging control system calculates the rate of change of photovoltaic power in real time:

[0152]

[0153] in This represents the real-time output power of the photovoltaic panel. The recommended detection period is 10ms-100ms. The selection of this period should balance detection sensitivity and system stability. A shorter period results in more sensitive detection but is more susceptible to noise interference; a longer period provides stronger anti-interference capabilities but increases response delay. The recommended default value is 50ms, which can be optimized and adjusted during the commissioning phase based on ambient lighting conditions and system noise levels.

[0154] when When the absolute value exceeds the preset fluctuation threshold, the charging control system determines that the photovoltaic power has fluctuated significantly.

[0155] The fluctuation threshold is based on the photovoltaic rated power. Based on this, it is recommended to set it to to The specific value can be dynamically adjusted according to weather conditions. Under sunny weather conditions, the light intensity is stable, so the threshold can be appropriately increased to avoid frequent triggering of compensation due to slight fluctuations. Under cloudy weather conditions, the light intensity changes drastically, so the threshold can be appropriately decreased to improve the compensation sensitivity and ensure a rapid response.

[0156] The system according to Pattern determination is performed based on the sign and amplitude:

[0157] when Furthermore, when its absolute value exceeds the fluctuation threshold, it indicates a significant decrease in photovoltaic power, and the system immediately enters the V2L collaborative compensation mode.

[0158] when Furthermore, when its amplitude exceeds the fluctuation threshold, and the photovoltaic power shows a continuous recovery trend, that is, within multiple consecutive detection cycles... The system determines that the photovoltaic power has been restored and enters the V2L power return process (called automatic callback), which gradually reduces the V2L discharge power and transfers the charging power share back to the photovoltaic input source;

[0159] To avoid frequent fluctuations in photovoltaic power around the threshold, which would cause frequent adjustments to V2L discharge power, a hysteresis range is introduced for fluctuation detection. When the change in photovoltaic power exceeds the threshold, it must fall back to a preset percentage below the threshold (50% of the threshold is recommended) before exiting the current mode, ensuring the stability of mode switching.

[0160] In step three, the V2L collaborative compensation mode is used for V2L collaborative compensation and power distribution optimization. Its core control logic is as follows: First, the charging control system calculates the power deficit and increases the V2L discharge power in real time to fill the gap caused by the decrease in photovoltaic power; Second, when photovoltaic and V2L supply power to the energy storage battery at the same time, the charging control system limits the total input power and optimizes the distribution among the input sources. While giving priority to the use of photovoltaic energy, it minimizes the V2L discharge of the electric vehicle to protect the vehicle battery.

[0161] The V2L collaborative compensation mechanism in the V2L collaborative compensation model is as follows:

[0162] When the charging control system detects a decrease in photovoltaic power, it automatically calculates the power deficit using the following formula:

[0163]

[0164] in

[0165] The target power of the photovoltaic system (i.e., the value sampled just before the moment of decrease). This represents the current actual photovoltaic power output.

[0166] The charging control system automatically increases the discharge power of V2L to compensate for the power deficit of photovoltaic power, thereby maintaining a stable total charging power of the energy storage battery. The formula is as follows:

[0167]

[0168] in This represents the current discharge power of V2L. The target discharge power for V2L;

[0169] Upon detecting a drop in photovoltaic power, the system sends a power dispatch command to the V2L device within 50ms, and the V2L completes power ramp-up within 100ms. The millisecond-level response speed of V2L is far superior to grid dispatch (seconds to minutes), enabling real-time compensation for sudden drops in photovoltaic power.

[0170] After V2L collaborative compensation control is activated, both photovoltaic and V2L input sources simultaneously supply power to the energy storage battery, with the total input power being the sum of the two. The charging control system performs total power limiting and allocation optimization, prioritizing the use of photovoltaic energy while minimizing V2L discharge to protect the vehicle battery, provided that charging demand is met. Specifically, to prevent the total power from exceeding the maximum allowable charging capacity of the energy storage battery, the charging control system limits the total power and optimizes the power allocation of each input source during the limiting process.

[0171] In step four, the charging control system determines the maximum allowable charging power of the energy storage battery. (Calculated and reported in real time by BMS) The total input power of photovoltaic and V2L is limited;

[0172] The power allocation of each input source follows the following priority rules: photovoltaic input source first (green energy, zero cost), V2L mobile input source second (as a compensation source, but constrained by vehicle battery life), and grid input source last (as a backup, highest cost).

[0173] Under this priority framework, the total power after limiting satisfies:

[0174]

[0175] when When the battery's state of charge (SOC) is close to full charge, the charging control system proportionally reduces the total input power, prioritizing the reduction of V2L discharge power to avoid overcharging.

[0176] The V2L power recovery process is as follows: After the photovoltaic power fluctuation detection unit determines that the photovoltaic power has dropped significantly, the charging control system must initiate a compensation action within a millisecond time scale to maintain the stability of the total charging power of the energy storage battery; if the response speed of the energy storage battery and the grid dispatch cannot match the millisecond time scale of the photovoltaic power drop, the charging control system calls the V2L mobile input source as a compensation source, and uses its millisecond-level fast response characteristics to immediately increase the discharge power to fill the gap caused by the drop in photovoltaic power.

[0177] In step four, when the photovoltaic power recovers, the charging control system automatically reduces the V2L discharge power, returning a portion of the charging power to the photovoltaic input source. The V2L discharge power recovery rate is matched with the photovoltaic power recovery rate. Specifically, the V2L discharge power recovery rate is set as follows: According to the photovoltaic power recovery rate Dynamically determined:

[0178]

[0179] in The maximum V2L callback rate is preset (recommended to be 10%-20% of the rated power per second) to avoid the impact of power sudden changes on the V2L system. The charging control system detects the photovoltaic power recovery status with a preset period of 100ms and adjusts the V2L discharge power periodically until the V2L discharge power returns to zero or the photovoltaic power recovers to the target value, thus realizing a smooth power transfer from V2L to photovoltaic.

[0180] The charging control system applies battery-friendly V2L discharge constraints to electric vehicles participating in photovoltaic and V2L collaboration. Specifically, during V2L collaborative compensation, the charging control system utilizes the energy from the vehicle's battery to fill the gap caused by the decrease in photovoltaic power. However, V2L discharge essentially consumes the cycle life of the vehicle's battery. Frequent deep discharges or high-power discharges accelerate battery aging, leading to degradation of the cathode material structure, increased lithium-ion loss, and a significantly increased capacity decay rate. Therefore, when utilizing V2L for power compensation, the charging control system must simultaneously apply discharge constraints to the vehicle's battery to balance the compensation demand with battery life protection. Battery-friendly discharge constraints are the specific implementation of the aforementioned life protection mechanism.

[0181] The charging control system applies the following constraints based on the vehicle battery's SOH (State of Health, i.e., the percentage of current battery capacity relative to the factory rated capacity, reflecting the degree of battery aging) and current SOC (State of Charge, i.e., the percentage of current remaining capacity relative to the full charge capacity):

[0182] A1. Maximum Depth of Discharge Limit Based on State of Harmony (SOH): SOH is a core indicator for measuring battery aging. A lower SOH indicates higher internal resistance and greater loss of active materials, meaning deeper discharge causes more significant damage to aging batteries. The system determines the recommended maximum depth of discharge under the current SOH based on the vehicle battery's cycle life curve. When the SOH is below 80%, it indicates that the battery has entered the accelerated aging stage. The system automatically reduces the maximum allowable depth of discharge and limits the energy release ratio of the battery in each discharge cycle in order to slow down the aging process.

[0183] A2. Discharge power limitation based on SOC: SOC reflects the battery's currently available remaining energy. The system calculates the recommended maximum discharge power based on the vehicle battery's current SOC. The lower the State of Charge (SOC), the less usable energy the battery has. If high-power discharge is performed at this level, the battery voltage will rapidly drop below the cutoff voltage, potentially triggering the vehicle's Battery Management System (BMS) protection mechanism and forcibly interrupting the discharge. Therefore, the system limits the discharge power as the SOC decreases to avoid high-power discharge in the low SOC range.

[0184] A3. Return Trip Battery Reserve Threshold: The system reserves the required battery power for the return trip based on the vehicle's destination information or the user's settings. This mechanism ensures that V2L discharge only consumes the "surplus" charge in the vehicle's battery, i.e. The corresponding power, of which

[0185] This is the current battery level. To meet the minimum power threshold required for the return trip, without depleting the energy reserves needed to ensure normal vehicle operation, thus preventing the vehicle from being unable to reach its destination due to V2L discharge.

[0186] Based on the above constraints, the system generates a battery-friendly discharge curve to control the discharge power, so that the discharge power gradually decreases as the SOC decreases.

[0187] The charging control system also performs V2L discharge state monitoring and protection to ensure that the system can safely exit the compensation state under any abnormal conditions. Specifically, the control process described above establishes a complete forward control link from photovoltaic fluctuation detection, V2L compensation initiation, power limiting to discharge constraint. However, the V2L discharge process involves real-time interaction between the energy storage system and external devices (electric vehicles). The temperature, SOC, and physical connection status of the vehicle battery and V2L devices may change at any time during the discharge process. These changes are not triggered by the energy storage system's control strategy but are uncontrolled changes caused by external factors (such as changes in ambient temperature, actual vehicle driving needs, user plugging and unplugging operations, etc.), and cannot be predicted and avoided through the forward control link described above. Therefore, the system needs to add an independent discharge state monitoring and protection mechanism on the basis of the above control link to cope with unpredictable state changes of external devices and ensure that the system can safely exit the compensation state under any abnormal conditions. V2L discharge state monitoring and protection is the aforementioned safety fallback mechanism. The system continuously monitors the output voltage, output current, vehicle SOC, and battery temperature of the V2L device at preset intervals (1 to 10 seconds recommended). When the following abnormal states are detected, the system executes corresponding protection actions:

[0188] B1. When the vehicle battery temperature exceeds the preset safety threshold, the system immediately stops V2L discharge and switches to photovoltaic single-input charging mode. Battery temperature is a critical boundary condition for the safe operation of lithium-ion batteries. Excessive temperature will accelerate the degradation of the positive electrode material structure and the thermal shrinkage of the separator, which may lead to thermal runaway in severe cases. Therefore, this protection action has the highest priority and is executed unconditionally.

[0189] B2. When the vehicle's State of Charge (SOC) falls below the minimum threshold reserved for the return trip, the system automatically reduces the V2L discharge power until it stops. This ensures that V2L discharge does not cause the vehicle's SOC to drop below the minimum charge threshold for guaranteed driving, thus preventing the vehicle from being unable to reach its destination due to V2L discharge.

[0190] When B3 and V2L devices are physically disconnected, the system detects the disconnection signal within 50ms and immediately shuts down the V2L input channel, switching to photovoltaic single-input charging mode or standby mode. This protection ensures the system can respond quickly when external equipment is unexpectedly disconnected, avoiding abnormal bus voltage caused by power loop open circuits.

[0191] The three protection actions mentioned above correspond to three different abnormal triggering conditions: abnormal battery temperature triggers unconditional shutdown, low SOC triggers gradual power reduction until shutdown, and physical disconnection of equipment triggers rapid channel shutdown. The response strategies of the three protections are matched with the urgency of the triggering conditions, together forming a complete V2L discharge safety protection chain.

[0192] The charging control system also performs dynamic adjustment and smoothing control of V2L discharge power. Specifically, the control flow described above (sections 3.1 to 3.4) establishes a complete control link from photovoltaic fluctuation detection, compensation initiation, power limiting to discharge constraints. This link ensures that V2L can quickly and accurately initiate compensation and apply necessary power limiting and battery protection constraints when photovoltaic power drops sharply. However, in the above control link, the command value of V2L discharge power may jump due to rapid fluctuations in photovoltaic power or detection noise. If the rate of change of these power commands is not limited, the vehicle battery will be frequently subjected to current surges, accelerating its aging. In addition, if the photovoltaic power frequently crosses the fluctuation detection threshold, it will cause frequent start-stop or large adjustment of V2L power, further aggravating system oscillation.

[0193] Therefore, during V2L discharge, the system also needs to smooth the changes in power command to eliminate the non-ideal factors at the control level. The dynamic adjustment and smoothing control mechanism described above is the specific implementation of this smoothing process. The system dynamically adjusts the V2L discharge power based on photovoltaic power fluctuations and changes in the SOC of the energy storage battery. To smooth the control process, the system employs the following mechanism:

[0194] C1. Power Change Rate Limitation: The rate of change of V2L discharge power shall not exceed the preset maximum rate of change (recommended to be 20% of rated power per second) to avoid sudden power surges impacting the vehicle battery and energy storage system. This mechanism directly limits the transient rate of power command and is the first line of defense for smooth control.

[0195] C2. Hysteresis Control: A hysteresis range (recommended 5% of rated power) is set in the photovoltaic power fluctuation detection to prevent frequent fluctuations in photovoltaic power near the threshold, which would cause frequent adjustments to the V2L discharge power. This mechanism prevents the system from repeatedly switching states near the detection threshold, serving as the second line of defense for smooth control.

[0196] C3. Filtering: The photovoltaic power sampling value is low-pass filtered (cutoff frequency recommended to be 10Hz) to remove high-frequency noise and avoid V2L malfunctions caused by sampling noise. This mechanism eliminates high-frequency disturbances in the input signal and is the third line of defense for smooth control.

[0197] The three mechanisms described above suppress abrupt changes in power command from different levels. The rate of change limit directly constrains the rate of power change, hysteresis control eliminates the back-and-forth switching near the threshold, and filtering removes noise components from the input signal. Working together, these three mechanisms ensure the smoothness and stability of V2L discharge power from the dimensions of "output rate of change," "state switching frequency," and "input signal quality," respectively, forming a complete power smoothing control chain.

[0198] Example 1

[0199] This embodiment provides a charging control method for a photovoltaic (PV) and V2L (Vehicle-to-Lane) coordinated energy storage system, applied to a portable energy storage power system comprising a PV input (rated power 400W, with MPPT controller) and a V2L mobile input (connected via an electric vehicle V2L interface, rated output power 2.4kW). The system includes a main control MCU (STM32F4 series Cortex-M4 processor), a PV MPPT tracking unit, a PV power fluctuation detection unit, a coordinated scheduling unit, a power limiting unit, and a status monitoring unit.

[0200] After system startup, the photovoltaic MPPT tracking unit continuously monitors the output voltage and current of the photovoltaic panel with a sampling period of 50ms, and tracks the maximum power point of the photovoltaic panel in real time using the perturbation-observation MPPT algorithm. Initially, with sufficient sunlight, the MPPT tracks the maximum power point of the photovoltaic panel.

[0201] The system uses photovoltaics as the main charging input source, and the total charging power of the energy storage battery is 380W.

[0202] At 10:30 AM, a cloud cover blocked the photovoltaic panels, causing the photovoltaic power to plummet from 380W to 120W within 200ms, a drop of 260W. The photovoltaic power fluctuation detection unit calculated the rate of change in photovoltaic power in real time with a period of 50ms. When the absolute value of W is 260W, which exceeds the preset fluctuation threshold of 50W, the system determines that the photovoltaic power has decreased significantly.

[0203] The coordinated scheduling unit automatically calculates the power deficit. W, and automatically increase the discharge power of V2L. The current discharge power of V2L is 0W (it was not started before), and the target discharge power is... W. The system sends a power scheduling command to the V2L device within 50ms, and the V2L completes the power ramp-up within 100ms, increasing from 0W to 260W, restoring the total charging power to [value missing]. W.

[0204] The power limiting unit detects the maximum allowable charging power of the energy storage battery. W, the current total power is 380W, which is within the limit, so the current allocation will be maintained.

[0205] The system simultaneously applies battery-friendly discharge constraints to the vehicle battery. The vehicle battery currently has a State of Harm (SOH) of 96% and a State of Charge (SOC) of 85%. Based on the cycle life curve, the maximum depth of discharge at the current SOH is determined. 80% capacity, reserve power for the return trip. With a corresponding SOC of 20%, the actual usable depth of discharge is less than It meets safety constraints and allows for full discharge.

[0206] The status monitoring unit continuously monitors the output voltage, output current and vehicle battery temperature of the V2L device at a 1-second interval, and all parameters are within the normal range.

[0207] During the V2L discharge power ramp-up process, the power change rate limiting mechanism ensures that the power change rate does not exceed the preset maximum change rate (recommended to be 20% of the rated power per second, i.e., 480W / s). The V2L discharge power smoothly ramps up from 0W to 260W in about 540ms, avoiding sudden power changes that could impact the vehicle battery.

[0208] At 10:35 AM, the clouds cleared, and the photovoltaic power recovered from 120W to 360W within 300ms. The photovoltaic power fluctuation detection unit detected a significant increase in photovoltaic power, and the collaborative scheduling unit initiated the V2L power restoration process. The V2L discharge power gradually decreased from 260W to 80W, with a power reduction rate of 60W / 100ms (600W / s), lower than the maximum restoration rate (20% of the rated power per second, i.e., 480W / s; the actual rate here was 600W / s, slightly higher than the upper limit, and the system automatically limited it to 480W / s). The restoration process was smooth and controllable. The total charging power was... W, the power limiting unit detected a total power exceeding 440W.

[0209] W, prioritize reducing V2L discharge power to 40W, total power is W meets the amplitude limiting requirements.

[0210] During photovoltaic power sampling, low-pass filtering (cutoff frequency 10Hz) effectively filters out high-frequency noise caused by rapid fluctuations in sunlight, preventing V2L malfunctions. Hysteresis control (hysteresis range is 5% of rated power, i.e., 20W) ensures that V2L does not frequently start and stop when photovoltaic power fluctuates near the threshold.

[0211] Example 2

[0212] The difference between this embodiment and Embodiment 1 is that the vehicle battery has a lower SOH (SOH=78%), and the system implements stricter battery-friendly discharge constraints.

[0213] When the collaborative scheduling unit calculates the target discharge power of V2L to be 260W, the battery-friendly discharge constraint unit adjusts the maximum depth of discharge based on the vehicle battery SOH=78%.

[0214] The discharge limit was reduced from 80% to 60%, and the maximum allowable discharge power was limited to 150W. The collaborative scheduling unit limited the actual discharge power of V2L to 150W, resulting in a power deficit. The remaining 110W in W will be reduced by the system to the total charging power target. W.

[0215] As V2L discharge proceeds, the vehicle battery's SOC gradually decreases from 85%. When the SOC drops to 50%, the system further limits the maximum discharge power from 150W to 100W based on the SOC-discharge power limit curve; when the SOC drops to 35%, the system limits the maximum discharge power to 50W; when the SOC approaches the return trip reserve threshold of 20%, the system gradually reduces the V2L discharge power to 0W to ensure the vehicle has sufficient return trip charge.

[0216] Example 3

[0217] The difference between this embodiment and Embodiment 1 is that the vehicle battery temperature rises abnormally during the discharge process, triggering the V2L discharge state monitoring and protection mechanism.

[0218] During V2L power compensation at 150W, the status monitoring unit detected that the vehicle battery temperature continuously rose from the normal value (35℃) to 55℃, exceeding the preset safety threshold (recommended 50℃). The system immediately stopped V2L discharge, switched to photovoltaic single-input charging mode, and simultaneously issued a battery temperature abnormality alarm to the user. The entire protection action was completed within 100ms, avoiding the risk of thermal runaway caused by sustained high battery temperature.

[0219] If the V2L device is accidentally unplugged by the user during discharge, the system will detect the disconnection signal within 50ms, immediately shut down the V2L input channel, and switch to photovoltaic single-input charging mode or standby mode to avoid abnormal bus voltage caused by power circuit open circuit.

[0220] Example 4

[0221] The difference between this embodiment and Embodiment 1 is that the photovoltaic power fluctuates continuously multiple times in a short period of time, the system performs continuous collaborative compensation, and verifies the effectiveness of the power smoothing control mechanism.

[0222] Under cloudy weather conditions, the photovoltaic (PV) power experienced multiple sudden drops and recoveries within 10 minutes (from 380W to 150W, 350W to 200W, and 400W to 180W, respectively). Each time the system detected a drop in PV power, it automatically increased the V2L discharge power within 100ms to compensate; each time the system detected a recovery in PV power, it automatically initiated the V2L power restoration process within 200ms.

[0223] Due to frequent fluctuations in photovoltaic power (with intervals of approximately 30-60 seconds between adjacent fluctuations), the hysteresis control mechanism (hysteresis range of 20W) effectively prevented the system from repeatedly switching states near the detection threshold, and the V2L discharge power did not experience frequent start-stop cycles. The power change rate limiting mechanism (maximum change rate of 480W / s) ensured that the V2L discharge power changed smoothly with each adjustment, without any power jumps. Low-pass filtering (cutoff frequency of 10Hz) eliminated high-frequency sampling noise, and the V2L did not malfunction.

[0224] Throughout the process, the total charging power of the energy storage battery fluctuated within ±5% of the target value. The V2L discharge power curve was smooth with no abrupt changes, effectively suppressing the impact of photovoltaic fluctuations on the charging process and avoiding the impact of power abrupt changes on the vehicle battery.

[0225] Example 5:

[0226] like Figure 2 As shown, at time t0, the system is in normal operating condition, and the photovoltaic output power is... V2L not started, total charging power is At time t1, the cloud cover begins to block the solar panels, and the solar power output is... Internal sudden drop The system detected the rate of change in power. Exceeding the preset fluctuation threshold This triggers the collaborative compensation mechanism. The system completes its response at time t2, with a detection delay of approximately [missing information]. (One detection cycle), the instruction is issued at Completed within the internal range, V2L power is in From the inside Climb to This compensates for all power deficits, restoring the total power to [value missing]. By time t3, the system had entered a stable operating state, and the photovoltaic power remained stable. V2L power maintained Total power is constant Power overshoot control within Within [a certain range]. The total time taken for the entire compensation process, from detection to recovery to a stable state, is approximately [a certain amount]. This demonstrates the technical effectiveness of V2L in compensating for photovoltaic fluctuations with millisecond-level response.

[0227] like Figure 3 As shown, at time t4, the photovoltaic power began to recover, and the system determined that the photovoltaic power had reached the target value. of (Right now This triggers the V2L power recovery process. Subsequently, the V2L discharge power is reduced from... Gradually pullback to callback rate Photovoltaic power recovery rate

[0228] and preset maximum callback rate Joint decision, that is ,in Take the rated power of V2L

[0229] of per second (in this example) After about Afterwards, until When the photovoltaic power is fully restored, the V2L power returns to zero. Throughout the entire recovery process, the total charging power remains constant without any power fluctuations, and the photovoltaic share is automatically returned.

[0230] Example 5:

[0231] This example proposes a charging control method for an energy storage system that integrates photovoltaic (PV) and V2L (Vehicle-to-Lane) technologies. V2L is defined as a real-time compensation source for PV power fluctuations. Through a unified and coordinated control closed loop of PV MPPT (Multi-Performance Testing) and V2L, real-time compensation is provided for sudden drops in PV power within a millisecond timescale.

[0232] In the method, the millisecond-level time scale includes: photovoltaic power fluctuation detection period of 10ms-100ms, power dispatch command issuance time of ≤50ms, and V2L power ramp-up completion time of ≤100ms.

[0233] The unified and coordinated control closed loop includes a series closed-loop link of photovoltaic MPPT tracking, photovoltaic power fluctuation detection, coordinated scheduling, power limiting, status monitoring and power smoothing control.

[0234] The method also includes battery-friendly V2L discharge constraints, which include a maximum depth of discharge limit based on SOH, a discharge power limit based on SOC, and a return trip power reserve threshold.

[0235] The method also includes automatic V2L callback during photovoltaic power recovery, with a callback rate. ,in For photovoltaic power recovery rate, Set the maximum callback rate.

[0236] The method also includes multi-dimensional safety protection for V2L discharge state, which immediately stops V2L when the vehicle battery temperature exceeds the threshold, gradually reduces power when the SOC is lower than the return trip reserved threshold, and cuts off the input channel within 50ms when the V2L device is disconnected.

[0237] This example presents a photovoltaic and V2L collaborative energy storage system charging control system, which is implemented using the methods described above. It includes: a photovoltaic MPPT tracking unit, a photovoltaic power fluctuation detection unit, a collaborative scheduling unit, a power limiting unit, a status monitoring unit, and a main control MCU.

[0238] This example possesses the following key technical aspects, resulting in beneficial effects and technical advantages.

[0239] Key Point 1: Redefining the V2L Role – From Load Power Supply to Real-Time Compensation Source for Photovoltaic Fluctuations.

[0240] In existing technologies, V2L is only used as an independent load power supply terminal. This invention redefines it for the first time as a "real-time compensation source for photovoltaic power fluctuations," utilizing the millisecond-level fast response characteristics of V2L to compensate for sudden drops in photovoltaic power in real time. This redefinition of its role is the core inventive concept of this invention.

[0241] Key Point 2: Unified and coordinated control closed loop of photovoltaic MPPT and V2L.

[0242] This invention establishes a deep collaborative control framework for photovoltaic MPPT tracking and V2L input, enabling V2L to automatically adjust the discharge power according to the real-time fluctuations of photovoltaic power, thereby realizing a control paradigm shift from "open-loop rule-based decision-making" to "closed-loop dynamic compensation".

[0243] Key point 3: Time parameter system for millisecond-level response speed.

[0244] This invention clarifies specific millisecond-level response time parameters: photovoltaic power fluctuation detection period of 10ms-100ms, power scheduling command issuance of 50ms, and V2L power ramp-up of 100ms, thus constructing a complete time parameter system to ensure that the system can complete the entire chain response from fluctuation detection to compensation execution within a millisecond time scale.

[0245] Key Point 4: Battery-friendly V2L discharge constraint mechanism.

[0246] This invention simultaneously applies a maximum discharge depth limit based on the vehicle battery's State of Health (SOH), a discharge power limit based on the State of Charge (SOC), and a return trip power reserve threshold during the V2L collaborative compensation process, achieving a balance between compensation effect and vehicle battery life protection.

[0247] Key Point 5: Automatic V2L Revert and Power Restoration Mechanism During Photovoltaic Recovery.

[0248] This invention automatically reduces V2L discharge power during photovoltaic power recovery, returning the charging power share to the photovoltaic input source. The callback rate matches the photovoltaic recovery rate, achieving smooth power transfer.

[0249] Key Point 6: Multi-dimensional safety protection for V2L discharge state.

[0250] This invention continuously monitors the temperature, SOC, and connection status of V2L devices, and performs graded protection actions for different anomaly types (temperature exceeding limits, SOC too low, device disconnection), forming a complete safety protection chain.

Claims

1. A charging control method for a photovoltaic and V2L-integrated energy storage system, characterized in that: The method defines the V2L provided by the electric vehicle battery as a real-time compensation source for photovoltaic power fluctuations, forming a collaborative control closed loop with the photovoltaic input source. The V2L is used to compensate for instantaneous fluctuations in photovoltaic power in real time, maintaining the stability of the total charging power of the energy storage system. The method first evaluates the photovoltaic power fluctuations using the maximum available photovoltaic power and the photovoltaic power change rate. If the fluctuation amplitude reaches the threshold that needs to be compensated, the power deficit is automatically calculated, and the discharge power of the V2L is increased in real time to compensate for the deficit, thereby maintaining the stability of the total charging power of the energy storage battery in the energy storage system.

2. The charging control method for a photovoltaic and V2L synergistic energy storage system according to claim 1, characterized in that: The V2L response speed is superior to that of grid dispatch; the control method includes the following steps; Step 1: Track the maximum power point of the photovoltaic panel in real time using the MPPT algorithm to obtain the current maximum available photovoltaic power, and continuously monitor the output voltage and output current of the photovoltaic panel at a preset sampling period; Step 2: The charging control system of the photovoltaic and V2L collaborative energy storage system calculates the rate of change of photovoltaic power in real time. When the absolute value of the rate of change of photovoltaic power exceeds the preset fluctuation threshold, it is determined that the photovoltaic power has fluctuated significantly and reached the threshold that needs to be compensated. Step 3: When a decrease in photovoltaic power is detected, the system automatically calculates the power deficit and immediately increases the discharge power of V2L to compensate for the deficit and maintain the stability of the total charging power of the energy storage battery. Step 4: The photovoltaic and V2L collaborative energy storage system limits the total input power of photovoltaic and V2L based on the maximum allowable charging power of the energy storage battery to avoid power surges impacting the energy storage system. Specifically, when the total power exceeds the maximum allowable charging power, the discharge power of V2L is reduced first to protect the vehicle battery, and then the input power of photovoltaic is reduced. When the photovoltaic power recovers, the system automatically reduces the discharge power of V2L and returns the charging power share to the photovoltaic input source. The recovery rate of V2L discharge power matches the recovery rate of photovoltaic power.

3. A charging control system for a photovoltaic and V2L-integrated energy storage system, using the charging control method for a photovoltaic and V2L-integrated energy storage system as described in claim 2, characterized in that: The energy storage system includes: a photovoltaic array, an MPPT controller, an energy storage battery pack, a battery management system (BMS), a V2L access interface supporting V2L discharge gun access for electric vehicles, a main control MCU, and a communication bus connecting the above units. The communication bus includes a CAN bus and an I2C bus. In the charging control system, the main control MCU communicates with the BMS via the CAN bus to obtain battery status parameters, communicates with the MPPT controller via the I2C bus or PWM signal to achieve maximum power point tracking control, and communicates with the V2L access interface via the I2C bus to obtain vehicle battery parameters and control V2L discharge power.

4. The charging control system for the photovoltaic and V2L synergistic energy storage system according to claim 3, characterized in that: When the charging control system is working, the V2L mobile input source formed by the electric vehicle is connected to the energy storage system through the AC charging interface; the charging control system achieves compatibility and adaptation for different vehicle models through a cooperative control method: the cooperative control method includes the following steps; Step S1: When the user inserts the V2L discharge gun of the electric vehicle into the AC input port of the energy storage system, the V2L access detection unit first detects the physical connection status of the V2L device, confirms that the discharge gun has established a reliable connection with the vehicle, and that the vehicle has started the inverter and begun to output AC power. Step S2: The charging control system communicates with the vehicle control unit (VCU) through the control guidance signal CP and the proximity guidance signal PP to establish a handshake connection and complete the function configuration, so that the vehicle can start supplying power to the energy storage system. Step S3: After a successful handshake, the system obtains vehicle battery parameters through standard communication protocols, including vehicle battery type, nominal voltage and capacity, current state of charge (SOC), current state of battery health (SOH), and maximum V2L output power. And the user-defined expected stay duration; Step S4: The system reads... The V2L target discharge power is limited to ensure it does not exceed the vehicle's capacity; simultaneously, the vehicle's SOC is monitored in real time. It stops V2L discharge and works in conjunction with the vehicle's own SOC protection mechanism. EV represents parameters related to electric vehicles, and PV represents parameters related to photovoltaics.

5. The charging control system for the photovoltaic and V2L synergistic energy storage system according to claim 4, characterized in that: In the aforementioned collaborative control method, the charging control system simultaneously applies battery-friendly discharge constraints to the vehicle battery. These constraints include a maximum depth of discharge limit based on the vehicle battery's State of Health (SOH), a discharge power limit based on the vehicle battery's State of Charge (SOC), and a return trip charge reserve threshold. This ensures that V2L discharge does not cause additional damage to the vehicle battery's lifespan. The system also continuously monitors the operating status of the V2L device. When the vehicle battery temperature exceeds a preset safety threshold or the V2L device is physically disconnected, the system automatically switches to photovoltaic single-input charging mode to ensure safe system operation.

6. The charging control system for the photovoltaic and V2L synergistic energy storage system according to claim 4, characterized in that: In step one, the charging control system uses the MPPT algorithm to track the maximum power point of the photovoltaic panel in real time to obtain the current maximum photovoltaic power. The MPPT algorithm adjusts the output voltage of the photovoltaic panel to ensure it always operates at the peak point of the power-voltage (PV) characteristic curve. The MPPT algorithm employs either the perturbation-observation method or the incremental conductance method. When using the perturbation-observation method, the charging control system continuously acquires the output voltage of the photovoltaic panel at a preset sampling period. and output current Calculate the current output power ; During each control cycle, the charging control system applies a small perturbation to the operating voltage of the photovoltaic panel and observes the direction of power change. If the power increases, the perturbation continues in the same direction; if the power decreases, the perturbation is reversed. Through the iterative process of perturbation, observation, and adjustment, the system gradually approaches the maximum power point and operates stably near the maximum power point. When the charging control system detects that the current environment is in a scenario of rapid changes in light, the system switches to the incremental conductance method. By comparing the instantaneous conductance with the amount of conductance change, the system determines the relative position of the maximum power point and tracks the changes in light to reduce power loss. The charging control system uses the maximum power point voltage it tracks as the target reference voltage for the MPPT controller and outputs it to the subsequent DC-DC converter, so that the photovoltaic panel always operates near the maximum power point.

7. The charging control system for the photovoltaic and V2L synergistic energy storage system according to claim 4, characterized in that: In step two, based on obtaining the current maximum available photovoltaic power, the charging control system continuously monitors the real-time changes in photovoltaic power to determine whether V2L collaborative compensation needs to be triggered or compensation needs to be withdrawn. If the photovoltaic output power is significantly intermittent and fluctuating due to the influence of light conditions, when cloud cover causes a sudden drop in photovoltaic power, the charging control system responds within a millisecond timescale and starts V2L compensation to maintain the stability of the total charging power. When sunlight is restored, the charging control system promptly exits the compensation and returns the charging power share to the photovoltaic input source, using the photovoltaic power fluctuation detection mechanism as the trigger basis for control decisions; The photovoltaic power fluctuation detection mechanism is as follows: The charging control system calculates the rate of change of photovoltaic power in real time: in This represents the real-time output power of the photovoltaic panel. For the detection cycle, when When the absolute value exceeds the preset fluctuation threshold, the charging control system determines that the photovoltaic power has fluctuated significantly. The fluctuation threshold is based on the photovoltaic rated power. Based on, set as to ; The system according to Perform pattern detection: when Furthermore, when its absolute value exceeds the fluctuation threshold, it indicates a significant decrease in photovoltaic power, and the system immediately enters the V2L collaborative compensation mode; when Furthermore, when its amplitude exceeds the fluctuation threshold, and the photovoltaic power shows a continuous recovery trend, that is, within multiple consecutive detection cycles... The system determines that the photovoltaic power has been restored and enters the V2L power return process, that is, gradually reducing the V2L discharge power and transferring the charging power share back to the photovoltaic input source; To avoid frequent fluctuations in photovoltaic power around the threshold, which would cause frequent adjustments to V2L discharge power, a hysteresis range is introduced for fluctuation detection. When the change in photovoltaic power exceeds the threshold, it must fall back to a preset ratio below the threshold before exiting the current mode, ensuring the stability of mode switching.

8. The charging control system for the photovoltaic and V2L synergistic energy storage system according to claim 4, characterized in that: In step three, the V2L collaborative compensation mode is used for V2L collaborative compensation and power distribution optimization. Its control logic is as follows: First, the charging control system calculates the power deficit and immediately increases the V2L discharge power to fill the gap caused by the decrease in photovoltaic power; Second, when photovoltaic and V2L are simultaneously supplying power to the energy storage battery, the charging control system limits the total input power and optimizes the distribution among the input sources. While giving priority to the use of photovoltaic energy, it minimizes the V2L discharge of the electric vehicle to protect the vehicle battery. The V2L collaborative compensation mechanism in the V2L collaborative compensation model is as follows: When the charging control system detects a decrease in photovoltaic power, it automatically calculates the power deficit using the following formula: in For photovoltaic target power, This represents the current actual photovoltaic power output. The charging control system automatically increases the discharge power of V2L to compensate for the power deficit of photovoltaic power, thereby maintaining a stable total charging power of the energy storage battery. The formula is as follows: in This represents the current discharge power of V2L. The target discharge power for V2L; After V2L collaborative compensation control is activated, both photovoltaic and V2L input sources simultaneously supply power to the energy storage battery, with the total input power being the sum of the two. The charging control system performs total power limiting and allocation optimization, prioritizing the use of photovoltaic energy while minimizing V2L discharge to protect the vehicle battery, provided that charging demand is met. Specifically: In step four, the charging control system determines the maximum allowable charging power of the energy storage battery. Limit the total input power of photovoltaic and V2L; The power allocation of each input source follows the following priority rule: photovoltaic input sources first, V2L mobile input sources second, and grid input sources last; Under this priority framework, the total power after limiting satisfies: when When the battery's state of charge (SOC) is close to full charge, the charging control system proportionally reduces the total input power, prioritizing the reduction of V2L discharge power to avoid overcharging. The V2L power recovery process is as follows: after the photovoltaic power fluctuation detection unit determines that the photovoltaic power has dropped significantly, the charging control system initiates a compensation action within a millisecond time scale to maintain the stability of the total charging power of the energy storage battery; if the response speed of the energy storage battery and the grid dispatch cannot match the millisecond time scale of the photovoltaic power drop, the charging control system calls the V2L mobile input source as a compensation source, and uses the fast response characteristics to immediately increase the discharge power to fill the gap caused by the drop in photovoltaic power.

9. The charging control system for a photovoltaic and V2L synergistic energy storage system according to claim 4, characterized in that: In step four, when the photovoltaic power recovers, the charging control system automatically reduces the V2L discharge power, returning a portion of the charging power to the photovoltaic input source. The V2L discharge power recovery rate is matched with the photovoltaic power recovery rate. Specifically, the V2L discharge power recovery rate is set as follows: According to the photovoltaic power recovery rate Dynamically determined: in To avoid power surges impacting the V2L system, the charging control system detects the photovoltaic power recovery status at a preset cycle and adjusts the V2L discharge power cycle by cycle until the V2L discharge power returns to zero or the photovoltaic power recovers to the target value, thus achieving a smooth power transfer from V2L to photovoltaic.

10. The charging control system for a photovoltaic and V2L synergistic energy storage system according to claim 4, characterized in that: The charging control system applies battery-friendly V2L discharge constraints to electric vehicles participating in photovoltaic and V2L collaboration; specifically, during V2L collaboration compensation, the charging control system applies the following constraints based on the vehicle battery's State of Health (SOH) and current State of Charge (SOC): A1. Based on the maximum depth of discharge limit under SOH, the system determines the recommended maximum depth of discharge under the current SOH according to the cycle life curve of the vehicle battery. When the state of oxygen (SOH) is below 80%, the system automatically reduces the maximum allowable depth of discharge, limiting the energy release ratio of the battery in each discharge cycle to slow down the aging process. A2. Based on SOC (State of Charge) discharge power limitation, the system calculates the recommended maximum discharge power according to the current SOC of the vehicle battery. The system thus limits the discharge power to decrease as the state of charge (SOC) decreases, avoiding high-power discharge in the low SOC range. A3. Return Trip Battery Reserve Threshold: The system reserves the required battery power for the return trip based on the vehicle's destination information or user settings. This mechanism ensures that V2L discharge only consumes the "surplus" charge in the vehicle's battery, i.e. The corresponding power, of which This is the current battery level. To meet the minimum power threshold required for the return trip, without depleting the energy reserves needed to ensure normal vehicle operation, thus preventing the vehicle from being unable to reach its destination due to V2L discharge. Based on the above constraints, the system gradually reduces the discharge power as the state of charge (SOC) decreases; The charging control system also performs V2L discharge state monitoring and protection to ensure that the system can safely exit the compensation state under any abnormal conditions. Specifically, the system continuously monitors the output voltage, output current, vehicle SOC, and battery temperature of the V2L device at preset intervals. When the following abnormal states are detected, the system executes corresponding protection actions: B1. When the vehicle battery temperature exceeds the preset safety threshold, the system immediately stops V2L discharge and switches to photovoltaic single-input charging mode; this protection action has the highest priority and is executed unconditionally. B2. When the vehicle's State of Charge (SOC) falls below the minimum threshold reserved for the return trip, the system automatically reduces the V2L discharge power until it stops. This ensures that V2L discharge does not cause the vehicle's SOC to drop below the minimum charge threshold for guaranteed driving, thus preventing the vehicle from being unable to reach its destination due to V2L discharge. When the B3 and V2L devices are physically disconnected, the system detects the disconnection signal and immediately shuts down the V2L input channel, switching to photovoltaic single-input charging mode or standby mode to avoid abnormal bus voltage caused by power circuit open circuit. The charging control system also performs dynamic adjustment and smoothing control of V2L discharge power. Specifically, during the V2L discharge process, the system smooths the changes in power command. The system dynamically adjusts the V2L discharge power based on photovoltaic power fluctuations and changes in the SOC of the energy storage battery. To smooth the control process, the system adopts the following mechanism: C1. Power change rate limit: The change rate of V2L discharge power shall not exceed the preset maximum change rate to avoid sudden power changes from impacting the vehicle battery and energy storage system. C2. Hysteresis control: Set a hysteresis interval in photovoltaic power fluctuation detection to avoid frequent fluctuations in photovoltaic power near the threshold, which would cause frequent adjustments to V2L discharge power. C3. Filtering: Perform low-pass filtering on the photovoltaic power sampling value to remove high-frequency noise and avoid V2L malfunction due to sampling noise.

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