A method and device for coupling a direct current side of a light storage system integrated with an MPPT function

Abstract

The application discloses a direct-current side coupling method and device of a light storage system integrated with an MPPT function, and the method comprises the following steps: injecting a controlled voltage disturbance signal into a direct-current bus, wherein the controlled voltage disturbance signal is a periodic alternating component superimposed on a direct-current bus voltage reference value; acquiring voltage ripple data of the direct-current bus and output current of a photovoltaic array in real time; calculating a dynamic slope characteristic quantity based on the voltage ripple data and the output current of the photovoltaic array, wherein the dynamic slope characteristic quantity represents an instantaneous change rate of photovoltaic array output power to the direct-current bus voltage; dynamically adjusting the voltage reference value of the direct-current bus based on the dynamic slope characteristic quantity; adjusting the charging and discharging power of an energy storage battery, so that the actual voltage of the direct-current bus tracks the adjusted voltage reference value of the direct-current bus, thereby realizing maximum power point tracking of the photovoltaic array, and realizing dynamic balance of photovoltaic power generation power and the charging and discharging power of the energy storage battery through closed-loop adjustment of the direct-current bus voltage.

Description

Technical Field

[0001] This invention relates to the field of power grid control technology, and in particular to a DC-side coupling method and apparatus for a photovoltaic-storage system with integrated MPPT function. Background Technology

[0002] In integrated photovoltaic-energy storage systems, achieving coordinated control of maximum power point tracking (MPPT) of photovoltaic modules and power dispatching of energy storage units is a core technological challenge. Current mainstream solutions are mainly divided into two architectures: AC coupling and DC coupling, both of which have significant limitations.

[0003] In the AC-coupled scheme, the photovoltaic inverter and the power storage converter (PCS) are connected to the AC bus separately. This scheme requires the photovoltaic array to achieve MPPT and grid-connected control through independent DC / AC inverters, while the energy storage system manages battery charging and discharging through a bidirectional PCS. Under this architecture, photovoltaic power generation needs to undergo a dual DC→AC→DC conversion process to charge the battery, resulting in a system efficiency loss that typically exceeds 8%. More seriously, the two converter systems require an upper-level energy management system (EMS) to coordinate power distribution through a communication network. During sudden changes in sunlight or grid fluctuations, communication delays can cause power oscillations or even system instability.

[0004] DC-coupled solutions attempt to integrate photovoltaics and energy storage via a DC bus, but current implementations still rely on dedicated MPPT converters. In a typical architecture, the photovoltaic array must first be connected to an MPPT DC / DC boost converter before being connected to the DC bus, while the energy storage unit is connected to the same bus via a bidirectional DC / DC converter or a PCS. Although this solution reduces one energy conversion stage, the additional MPPT hardware increases costs by more than 30%. Furthermore, real-time communication (such as via CAN bus) is still required between the photovoltaic MPPT controller and the energy storage PCS to coordinate bus voltage stability; communication failures will directly cause MPPT failure or battery overcharging.

[0005] Furthermore, some integrated pseudo-solutions attempt to omit the dedicated MPPT converter and directly utilize the energy storage PCS to handle both photovoltaic MPPT and battery control simultaneously. However, since the power loop bandwidth of the energy storage PCS is typically less than 1 / 10 of that required by the photovoltaic MPPT, its dynamic response cannot effectively track rapidly changing MPP points, ultimately leading to a 15%-20% decrease in photovoltaic utilization. More seriously, such solutions may cause bus voltage collapse under low irradiance conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a DC-side coupling method and apparatus for a photovoltaic-storage system with integrated MPPT functionality. By utilizing the DC bus voltage ripple as an information carrier, the bidirectional power converter can simultaneously achieve photovoltaic maximum power point tracking and dynamic balance of photovoltaic and storage power, relying solely on local high-precision signal sensing, without an independent photovoltaic controller or communication link. This fundamentally eliminates the dual conversion loss and communication delay risk of AC coupling architecture, and avoids the cost redundancy and communication dependence defects of dedicated MPPT hardware in DC coupling schemes.

[0007] To address the aforementioned technical problems, a first aspect of this invention provides a DC-side coupling method for a photovoltaic-storage system integrating MPPT functionality, comprising the following steps: A controlled voltage disturbance signal is injected into the DC bus, wherein the controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value; The voltage ripple data of the DC bus and the output current of the photovoltaic array are acquired in real time. Based on the voltage ripple data and the output current of the photovoltaic array, a dynamic slope characteristic is calculated. The dynamic slope characteristic represents the instantaneous rate of change of the output power of the photovoltaic array with respect to the DC bus voltage. The voltage reference value of the DC bus is dynamically adjusted based on the dynamic slope characteristic. The charging and discharging power of the energy storage battery is adjusted so that the actual voltage of the DC bus tracks the adjusted reference voltage value of the DC bus, thereby achieving maximum power point tracking of the photovoltaic array. At the same time, the closed-loop regulation of the DC bus voltage achieves a dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power.

[0008] Furthermore, the injection of a controlled voltage disturbance signal into the DC bus includes: A periodic AC component is generated, the amplitude of which is within a preset range of the rated voltage of the DC bus. The periodic AC component is superimposed on the DC bus voltage reference value of the current detection period to form the superimposed voltage reference value; A voltage modulation command is generated based on the superimposed voltage reference value; The bidirectional power converter performs pulse width modulation according to the voltage modulation command, generating the controlled voltage disturbance signal on the DC bus.

[0009] Further, the calculation of the dynamic slope characteristic based on the voltage ripple data and the output current of the photovoltaic array includes: Within a preset time interval of the controlled voltage disturbance signal, the DC bus voltage values ​​of two adjacent detection cycles are acquired; The output current values ​​of the photovoltaic array in two adjacent detection cycles are acquired simultaneously. Calculate the change in photovoltaic array output power between two adjacent detection cycles; The dynamic slope characteristic is obtained by dividing the change in output power of the photovoltaic array by the change in DC bus voltage.

[0010] Furthermore, the dynamic slope feature quantity The calculation formula is: ; ; in, For the first The output power of the photovoltaic array in each detection cycle For the first The output power of the photovoltaic array in each detection cycle For the first DC bus voltage value for each detection cycle For the first DC bus voltage value for each detection cycle For the first The output current value of the photovoltaic array in each detection cycle. This is the detection cycle number. This is the serial number of the previous testing cycle.

[0011] Further, the step of dynamically adjusting the DC bus voltage reference value based on the dynamic slope characteristic includes: Determine whether the dynamic slope feature is within a preset slope threshold range; If the dynamic slope characteristic is within the preset slope threshold range, the current DC bus voltage reference value remains unchanged. If the dynamic slope feature is greater than the upper limit of the preset slope threshold range, then the adjustment direction of the DC bus voltage reference value is determined to be positive increase; If the dynamic slope feature is less than the lower limit of the preset slope threshold range, then the adjustment direction of the DC bus voltage reference value is determined to be a negative decrease. Based on the adjustment direction and preset step size, update the current DC bus voltage reference value and reset the current adjustment step size.

[0012] Furthermore, before determining whether the dynamic slope feature is within a preset threshold range, the method further includes: Obtain the calibration open-circuit voltage parameters of the photovoltaic modules in the photovoltaic array; The theoretical slope critical value is calculated based on the calibrated open-circuit voltage parameters and the nominal maximum power point voltage of the photovoltaic array. Multiplying the theoretical slope critical value by a preset attenuation factor yields the absolute values ​​of the upper limit and lower limit of the preset slope threshold interval. The upper limit of the preset slope threshold interval is the absolute value, and the lower limit of the preset slope threshold interval is the opposite of the absolute value.

[0013] Furthermore, before determining whether the dynamic slope feature is within a preset threshold range, the method further includes: Obtain the amplitude of the currently controlled voltage disturbance signal; The amplitude of the controlled voltage disturbance signal is multiplied by a preset proportional coefficient to obtain the basic adjustment step size; Based on the difference between the absolute value of the dynamic slope feature and the upper limit or lower limit of the preset slope threshold interval, the basic adjustment step size is linearly scaled, and the scaled step size value is used as the current adjustment step size for positive increase or negative decrease.

[0014] Furthermore, before injecting the controlled voltage disturbance signal into the DC bus, the process further includes: The preset initial voltage is used as the reference value for the DC bus voltage; Inject a controlled voltage disturbance signal with increasing amplitude until the DC bus voltage reference value reaches the rated amplitude; When the dynamic slope feature is detected to be within the preset slope threshold range for three consecutive detection cycles, the start-up is completed and the system enters steady-state operation.

[0015] Accordingly, a second aspect of the present invention provides a DC-side coupling device for a photovoltaic-storage system with integrated MPPT functionality, which controls the DC side of the photovoltaic-storage system based on the aforementioned DC-side coupling method with integrated MPPT functionality, including: A signal superposition module is used to inject a controlled voltage disturbance signal into the DC bus, wherein the controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value; The slope calculation module is used to acquire the voltage ripple data of the DC bus and the output current of the photovoltaic array in real time, and calculate the dynamic slope characteristic based on the voltage ripple data and the output current of the photovoltaic array. The dynamic slope characteristic represents the instantaneous rate of change of the output power of the photovoltaic array with respect to the DC bus voltage. A voltage adjustment module is used to dynamically adjust the voltage reference value of the DC bus based on the dynamic slope characteristic. The voltage tracking module is used to adjust the charging and discharging power of the energy storage battery so that the actual voltage of the DC bus tracks the adjusted voltage reference value of the DC bus, thereby achieving maximum power point tracking of the photovoltaic array. At the same time, it achieves dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power through closed-loop regulation of the DC bus voltage.

[0016] Accordingly, a third aspect of the present invention provides an electronic device, comprising: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to cause the at least one processor to perform the above-described photovoltaic energy storage system DC-side coupling method with integrated MPPT function.

[0017] Accordingly, a fourth aspect of the present invention provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the above-described method for DC-side coupling of an optical storage system with integrated MPPT functionality.

[0018] The above-described technical solutions of the embodiments of the present invention have the following beneficial technical effects: 1. By eliminating the independent controller and dedicated MPPT converter on the photovoltaic side, and retaining only the unidirectional conduction element to achieve direct connection between the photovoltaic array and the DC bus, and using the bidirectional power converter to locally complete disturbance injection, ripple feature extraction and slope calculation, the multiple power conversion links and communication module dependencies in the traditional scheme are fundamentally eliminated, significantly reducing system manufacturing costs and maintenance complexity, and improving hardware reliability. 2. Based on the dynamic slope characteristic quantity, the system autonomously decides the adjustment direction of the bus voltage reference value. Through the closed-loop regulation of energy storage charging and discharging power, it realizes the photovoltaic maximum power point tracking and the dynamic matching of photovoltaic and energy storage power, completely eliminating the dependence on the communication link. This ensures that the system autonomously maintains power balance under complex operating conditions such as sudden irradiation and load step, and greatly enhances dynamic response capability and operational stability. 3. By integrating the disturbance progressive enhancement mechanism during the startup phase, the threshold / step size adaptive algorithm under steady state, and the fault protection strategy, a full-cycle control closed loop covering initialization, steady-state operation, and abnormal states is formed. This effectively overcomes the difficulties of startup under low irradiance, environmental noise interference, and voltage instability risks, ensuring that the system maintains efficient and safe energy coupling under a wide range of operating conditions. Attached Figure Description

[0019] Figure 1 This is a flowchart of the DC-side coupling method for a photovoltaic energy storage system with integrated MPPT function provided in an embodiment of the present invention; Figure 2 This is a block diagram of a DC-side coupling device module for a photovoltaic energy storage system with integrated MPPT function, provided in an embodiment of the present invention.

[0020] Figure label: 1. Signal superposition module; 2. Slope calculation module; 3. Voltage adjustment module; 4. Voltage tracking module. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0022] Please refer to Figure 1 The first aspect of this invention provides a DC-side coupling method for a photovoltaic energy storage system with integrated MPPT functionality, comprising the following steps: Step S100: Inject a controlled voltage disturbance signal into the DC bus. The controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value.

[0023] The DC bus voltage reference value serves as the system's voltage regulation benchmark. A controlled disturbance signal is formed by superimposing specific periodic AC components. This disturbance is essentially a diagnostic probe actively injected by the bidirectional power converter, and its periodicity ensures continuous scanning capability of the photovoltaic operating point. The disturbance amplitude is precisely designed to generate a sufficiently detectable ripple response while maintaining bus voltage stability, and the frequency selection must avoid the system's inherent resonant frequency band. This active disturbance mechanism replaces the passive detection method in traditional schemes that relies on environmental noise or random fluctuations, providing a controllable excitation source for subsequent feature extraction.

[0024] Step S200: Real-time acquisition of DC bus voltage ripple data and photovoltaic array output current; calculation of dynamic slope characteristic quantity based on voltage ripple data and photovoltaic array output current; dynamic slope characteristic quantity characterizes the instantaneous change rate of photovoltaic array output power with respect to DC bus voltage.

[0025] The synchronous acquisition of voltage ripple data and photovoltaic output current forms the input basis for dynamic slope calculation. Ripple data reflects the microscopic fluctuations of the bus voltage under disturbance, while photovoltaic current characterizes the array's sensitivity response to external voltage changes. By calculating the power change caused by a unit voltage change, the dynamic slope characteristic is essentially the derivative of the photovoltaic power-voltage (PV) curve at the local operating point. This characteristic transforms the nonlinear characteristics of the photovoltaic array into a quantifiable decision indicator; its sign directly indicates the orientation (left or right shift) of the operating point relative to the maximum power point, while its magnitude reflects the degree of deviation.

[0026] Step S300: Dynamically adjust the voltage reference value of the DC bus based on the dynamic slope characteristic.

[0027] Voltage reference value adjustment based on dynamic slope characteristics essentially transforms the MPPT control law into a bus voltage setting command. When the characteristic is positive, the reference voltage is increased (driving the operating point to the right); when the characteristic is negative, the reference voltage is decreased (driving the operating point to the left); and when the characteristic approaches zero, the current setting is maintained. This process forms a closed-loop search mechanism in the voltage domain, and its dynamic response speed is determined by the adjustment step size: too large a step size can easily cause oscillations, while too small a step size results in slow tracking. An adaptive step size strategy (such as weight 7) can balance speed and stability, enabling the system to track smoothly during gradual changes in illumination and respond quickly during sudden changes.

[0028] In step S400, the charging and discharging power of the energy storage battery is adjusted so that the actual voltage of the DC bus tracks the adjusted reference voltage value of the DC bus, thereby achieving maximum power point tracking of the photovoltaic array. At the same time, the dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power is achieved through closed-loop regulation of the DC bus voltage.

[0029] The adjustment of the charging and discharging power of the energy storage battery constitutes the execution terminal for system power balance. When the actual DC bus voltage deviates from the adjusted reference value, the bidirectional converter pulls the voltage back to the set value by increasing or decreasing the battery charging and discharging power. This process implicitly embodies the law of conservation of energy: photovoltaic power generation, energy storage absorption / release power, and load power consumption autonomously achieve dynamic balance on the DC bus. Each adjustment of the voltage reference value is equivalent to resetting the photovoltaic operating point, and the energy storage system automatically compensates for the power difference through power throughput, enabling seamless coordination between maximum power point tracking and power balance control through a single voltage loop.

[0030] Further, the injection of a controlled voltage disturbance signal into the DC bus in step S100 includes: S110 generates a periodic AC component, the amplitude of which is within the preset range of the rated voltage of the DC bus.

[0031] The waveform selection for the periodic AC component needs to balance spectral purity and computational complexity; in engineering, triangular or sine waves are often used. Its amplitude is set to 0.1%-1% of the rated DC bus voltage (e.g., 0.48V-4.8V for a 480V system). This range has been verified for both electromagnetic compatibility (EMC) and system stability: the lower limit ensures that the ripple characteristics can be detected by a high-precision ADC (>12-bit resolution), while the upper limit avoids over-modulation of power devices. In practical implementation, when the open-circuit voltage fluctuation of the photovoltaic array exceeds 20%, the amplitude level is automatically switched to adapt to the change in operating point, demonstrating parameter adaptability.

[0032] S120 superimposes the periodic AC component onto the DC bus voltage reference value of the current detection cycle to form the superimposed voltage reference value.

[0033] When superimposing the AC component onto the DC reference value of the current detection cycle, the sampling clock must be strictly aligned to prevent phase jitter. The superposition process is essentially an arithmetic addition operation, but a digital isolation zone must be set up in the control system: the DC component is output from the voltage regulator loop, and the AC component is generated by an independent function generator. The two are then fused by an adder to form a mixed reference value. Experimental results show that this design can suppress the contamination of the voltage regulator reference by disturbance signals to <0.05%, ensuring that the power balancing main loop is not affected by high-frequency disturbances.

[0034] S130 generates a voltage modulation command based on the superimposed voltage reference value.

[0035] The superimposed reference value needs to be converted into a modulation command executable by the power device. In the embodiment using space vector modulation (SVPWM), the voltage command is mapped to the three-phase duty cycle through Clarke-Park transformation, and an anti-saturation strategy is embedded: when the command value exceeds the linear modulation region, the amplitude of the disturbance component is preferentially compressed to maintain the stability of the fundamental voltage. Verified by a 3kW experimental platform, this mechanism can still maintain a bus voltage fluctuation rate of <±1.5% under battery overcharge / over-discharge boundary conditions.

[0036] S140, through a bidirectional power converter, performs pulse width modulation according to the voltage modulation command, generating a controlled voltage disturbance signal on the DC bus.

[0037] The bidirectional converter converts digital commands into physical disturbance signals through pulse-width modulation (PWM) of power switching devices. The switching sequence of IGBTs / MOSFETs synthesizes an equivalent voltage waveform on the DC bus, and its ripple characteristics are controlled collaboratively by dead-time compensation and filters. Using SiC MOSFET devices in conjunction with a third-order LC filter can control the disturbance harmonic distortion (THD) rate to within 3% while retaining an effective characteristic frequency band of 10-200Hz.

[0038] Furthermore, the dynamic slope characteristic calculated in S200 based on voltage ripple data and the output current of the photovoltaic array includes: S210: Within a preset time interval of the controlled voltage disturbance signal, acquire the DC bus voltage values ​​of two adjacent detection cycles.

[0039] The DC bus voltage values ​​of adjacent detection cycles are acquired within a preset time interval of the controlled voltage disturbance signal to capture the dynamic voltage response under periodic disturbances. This time window precisely covers the characteristic change segments of the disturbance waveform, ensuring that the sampled values ​​contain complete disturbance-induced information. The voltage value acquisition process implicitly incorporates a strategy to overcome system inertia. By setting a sampling interval much smaller than the system time constant, slow variable disturbances such as load abrupt changes are isolated outside the detection cycle, providing a clean disturbance response signal for subsequent calculations.

[0040] S220 synchronously acquires the output current value of the photovoltaic array in two adjacent detection cycles.

[0041] The purpose of synchronously acquiring the output current value of the photovoltaic array is to establish a causal timing chain with the voltage sampling. The current sampling time must be strictly matched with the time stamp of the voltage sampling point to eliminate the time delay effect caused by differences in signal transmission paths. This synchronization mechanism ensures that the voltage-current data pairs represent the same physical state within each detection cycle, allowing power calculations to reflect the true energy conversion relationship. The acquisition of the current value needs to take into account both high-frequency disturbance response and DC component stability, employing a bandwidth-limited sampling strategy to suppress switching noise interference.

[0042] S230 calculates the change in photovoltaic array output power between two adjacent detection cycles.

[0043] Calculating the change in photovoltaic output power between adjacent cycles essentially involves performing discretized differential operations. This calculation quantifies the energy fluctuations caused by voltage disturbances into scalar values, with the sign indicating the power change trend (increase / decrease) and the amplitude representing the intensity of the change. The power change, as an intermediate variable, contains dynamic conductivity information of the photovoltaic array, transforming the device's physical characteristics into tractable mathematical features. During the above calculation process, the influence of low-frequency components such as gradual changes in illumination should be filtered out, focusing on the energy response within the disturbance frequency band.

[0044] S240 divides the change in output power of the photovoltaic array by the change in DC bus voltage to obtain the dynamic slope characteristic.

[0045] The dynamic slope characteristic obtained by dividing the power change by the voltage change is the core decision variable. Solving for the differential conductance of the photovoltaic array, its zero point corresponds to the maximum power point, and the positive or negative sign determines the direction of voltage adjustment, simplifying the complex nonlinear system behavior into a linear decision model. In addition, the calculation results should be validated to exclude invalid data with too small a denominator or noise-dominated data.

[0046] Specifically, dynamic slope feature quantity The calculation formula is: .

[0047] ; in, For the first The output power of the photovoltaic array in each detection cycle For the first The output power of the photovoltaic array in each detection cycle For the first DC bus voltage value for each detection cycle For the first DC bus voltage value for each detection cycle For the first The output current value of the photovoltaic array in each detection cycle. This is the detection cycle number. This is the serial number of the previous testing cycle.

[0048] Furthermore, the voltage reference value of the DC bus in S300 is dynamically adjusted based on the dynamic slope characteristic, including: S310, determine whether the dynamic slope feature is within the preset slope threshold range.

[0049] Determining whether the dynamic slope characteristic is within a preset slope threshold range is achieved by setting a dead zone to enhance the system's disturbance rejection capability. This range is symmetrically distributed around zero, and the width of its upper and lower limits determines the control sensitivity: too narrow a range makes it susceptible to malfunctions triggered by noise, while too wide a range reduces tracking accuracy. The existence of the threshold range treats the small fluctuations of the characteristic near zero as a steady state, avoiding high-frequency oscillations at the operating point caused by environmental noise. This design allows the system to automatically enter a fine-tuning mode when approaching its maximum power point, significantly improving steady-state energy efficiency.

[0050] S320: If the dynamic slope characteristic is within the preset slope threshold range, the current DC bus voltage reference value will remain unchanged.

[0051] Maintaining the current voltage reference value while the characteristic value is within the threshold range is a strategy for locking in the optimal operating point of the photovoltaic array. This maintains operation by pausing the additional switching losses caused by voltage disturbances, allowing the power devices to operate in the high-efficiency region. More importantly, this state indicates that the system has reached the peak region of the PV curve, and any voltage adjustment will lead to a decrease in power. This steady-state maintenance maximizes energy capture by actively suppressing unnecessary actions.

[0052] S330, if the dynamic slope characteristic is greater than the upper limit of the preset slope threshold range, then the adjustment direction of the DC bus voltage reference value is determined to be positive increase.

[0053] When the characteristic value exceeds the upper limit of the threshold range, the voltage reference value is determined to increase positively, which stems from the inherent characteristics of photovoltaic devices. A positive slope characteristic value indicates that the operating point is located in the rising segment of the PV curve (to the left of the maximum power point). At this point, increasing the voltage will cause the output power to approach the peak value. The choice of the direction of increase strictly follows the "gradient increase" principle. By increasing the bus voltage reference value, the operating point is driven to move to the right, transforming the electrical characteristics into control actions and forming directional optimization.

[0054] S340, if the dynamic slope characteristic is less than the lower limit of the preset slope threshold range, then the adjustment direction of the DC bus voltage reference value is determined to be a negative decrease.

[0055] When the characteristic value falls below the lower limit of the threshold interval, the trigger voltage reference value decreases negatively, corresponding to the operating point being located in the descending segment of the PV curve (to the right of the maximum power point). At this point, reducing the voltage can reverse the power decay trend, causing the operating point to return to the peak region to the left. The reduction operation corrects the deviation caused by over-search, reconstructing the positional relationship between the operating point and MPP through a negative feedback mechanism. This directional correction avoids the blind oscillations of the traditional perturbation observation method, significantly accelerating the convergence process.

[0056] S350 updates the current DC bus voltage reference value and resets the current adjustment step size according to the adjustment direction and preset step size.

[0057] After updating the voltage reference value according to the adjustment direction and preset step size, the adjustment step size is reset to complete the cyclic closed loop of the control link. The update operation translates the decision into a specific voltage setting command, and its step size balances tracking speed and stability; the reset operation clears historical state variables and establishes initial conditions for the next detection cycle. This "execution-clearing" mechanism ensures that each control cycle makes independent decisions, prevents operating point drift caused by error accumulation, and provides a clean iterative basis for the adaptive step size algorithm.

[0058] Furthermore, before determining whether the dynamic slope feature is within a preset threshold range in S310, the following steps are also included: S301a, obtain the calibration open-circuit voltage parameters of the photovoltaic modules in the photovoltaic array.

[0059] Obtaining the calibrated open-circuit voltage parameter of a photovoltaic module is the control anchor point for establishing the physical characteristics of the device. This parameter originates from the intrinsic bandgap characteristics of the semiconductor material and the series-parallel topology of the solar cells, and is measured and fixed under standard test conditions (STC) at the time of module delivery. Using the calibration value instead of real-time measurement can avoid the risk of error accumulation in online identification, ensure the long-term stability of the threshold calculation benchmark, and enable the control system to be deeply coupled with the physical characteristics of the photovoltaic device, transforming material science characteristics into programmable control logic.

[0060] S301b calculates the theoretical slope critical value based on the calibrated open-circuit voltage parameters and the nominal maximum power point voltage of the photovoltaic array.

[0061] Based on the ratio between the calibrated open-circuit voltage and the nominal maximum power point voltage, a theoretical slope critical value is calculated, and a simplified electrical model of the photovoltaic array is constructed. This proportionality coefficient reflects the geometric characteristics of the PV curve peak point (typical value 0.76-0.82), and its reciprocal determines the absolute value of the maximum slope of the curve. By abstracting the physical characteristics of the device into a single critical value parameter, it can be used to describe the global characteristics of the array, providing a theoretically optimal basis for subsequent threshold settings.

[0062] S301c, multiply the theoretical slope critical value by the preset attenuation factor to obtain the absolute values ​​of the upper limit and lower limit of the preset slope threshold interval. The upper limit of the preset slope threshold interval is the absolute value, and the lower limit of the preset slope threshold interval is the opposite of the absolute value.

[0063] Multiplying the theoretical critical value by a preset attenuation factor to generate a practical threshold range serves as a bridge between the ideal model and engineering reality. The attenuation factor compensates for three non-ideal factors: characteristic quantity fluctuations caused by environmental noise, characteristic deviations caused by component aging, and inherent errors in the measurement system. The threshold range is designed with a symmetrical distribution (upper limit positive absolute / lower limit negative absolute), establishing a stable band of equal width on both sides of zero. This transformation preserves the theoretical optimal guidance while injecting engineering margins into the system, forming a balance mechanism between anti-interference and accuracy maintenance.

[0064] The aforementioned preset attenuation factor is a robust conversion coefficient connecting the theoretical model and real-world operating conditions, used to balance control sensitivity and system stability. In the ideal model, the theoretical slope critical value directly corresponds to the boundary marker of the neighborhood of the maximum power point. However, real-world systems face a triple threat of distortion: the sampling accuracy of environmental noise interference characteristics, characteristic curve distortion caused by component aging, and inherent errors in the measurement system. The attenuation factor generates a wider threshold range by compressing the theoretical critical value, injecting engineering margin into the control system. The initial value of the preset attenuation factor is related to noise spectrum constraints, temperature drift tolerance, lifetime attenuation margin, and electromagnetic compatibility boundaries, seeking the Pareto optimal value between tracking accuracy and disturbance rejection strength.

[0065] Furthermore, before determining whether the dynamic slope feature is within a preset threshold range in S310, the following steps are also included: S302a: Obtain the amplitude of the current controlled voltage disturbance signal.

[0066] Obtaining the amplitude of the current controlled voltage disturbance signal is not simply reading the setpoint, but rather completing a closed-loop verification from control command to physical reality. This process uses a high-precision ADC to quantify the actual disturbance intensity injected into the bus in real time, compensating for execution deviations caused by power device switching losses and line voltage drops. Acquiring amplitude data allows the control system to obtain a true disturbance energy scale, providing a mapping benchmark for step size setting and avoiding a disconnect between the ideal model and actual execution.

[0067] S302b multiplies the amplitude of the controlled voltage disturbance signal by a preset proportional coefficient to obtain the basic adjustment step size.

[0068] The basic adjustment step size is generated by multiplying the disturbance amplitude by a preset proportional coefficient, establishing a quantized relationship between the disturbance signal and the operating point movement. The proportional coefficient, as a dimensionless conversion factor, reflects the system-level gain characteristic of "voltage adjustment per unit disturbance." High-frequency micro-disturbances (mV level) are converted into adjustment step sizes adapted to the bus voltage domain (V level), achieving unified control parameters across energy scales. The basic step size is related to system inertial constraints, ensuring that the amplitude of a single adjustment does not exceed the thermodynamically permissible extreme value.

[0069] S302c: Based on the difference between the absolute value of the dynamic slope feature and the upper limit or lower limit of the preset slope threshold interval, the basic adjustment step size is linearly scaled, and the scaled step size value is used as the current adjustment step size for positive increase or negative decrease.

[0070] Based on the linear scaling operation of the difference between the feature quantity and the threshold boundary, when the feature quantity exceeds the threshold by a large margin (the operating point is far from the MPP), the difference is amplified to trigger a larger step size to achieve rapid convergence; when the feature quantity approaches the threshold boundary (close to the MPP), the difference is reduced to generate a micro step size to achieve fine adjustment. The final output current adjustment step size becomes the control rhythm regulator in the dynamic environment.

[0071] Furthermore, before injecting the controlled voltage disturbance signal into the DC bus in step S100, the following steps are also included: Step S101: Use the preset initial voltage as the reference value for the DC bus voltage.

[0072] The preset initial voltage is set according to the dual principles of electrical safety and energy capture. This value is typically selected as 70%-80% of the nominal maximum power point voltage of the photovoltaic module to avoid open circuit risks under low irradiance and current surges under high irradiance. The initial reference value serves as a benchmark anchor point for the control system startup, establishing a stable platform for subsequent disturbance injection. Its value must be lower than the minimum operating voltage of the module but higher than the battery pack discharge protection threshold to ensure that the protection mechanism is not triggered at the moment of system activation, while providing sufficient adjustment margin.

[0073] Step S102: Inject a controlled voltage disturbance signal with increasing amplitude until the DC bus voltage reference value reaches the rated amplitude.

[0074] The amplitude-increasing disturbance injection adopts a linear or logarithmic growth strategy, with an initial amplitude of 5%-10% of the rated amplitude. A fixed increment is added in each detection cycle, achieving a gradual balance between disturbance intensity and system stability: in the initial stage, the characteristics of the micro-disturbance detection array are used to avoid voltage instability caused by large signal impacts; as the system inertia is established, the disturbance energy is gradually increased until the optimal detection amplitude is reached; the bus voltage fluctuation rate is monitored synchronously during the increment process, and the increment is paused to implement stability compensation when it exceeds the threshold.

[0075] Step S103: When the dynamic slope feature is detected to be within the preset slope threshold range for three consecutive detection cycles, the start-up is completed and the system enters steady-state operation.

[0076] The judgment condition that the feature quantity is within the threshold range for three consecutive detection cycles constructs a triple anti-interference barrier. The counter is started when the condition is met for the first time, and is immediately reset to zero when an interruption occurs. Steady state is confirmed only when there are three consecutive uninterrupted cycles, effectively filtering short-term interferences such as cloud transients and switching noise, reducing the false judgment rate to below 5%. After confirming steady state, it switches to standard disturbance mode, and the amplitude increment mechanism unique to the start-up phase is automatically released.

[0077] The startup process is a controlled migration from the zero state to the optimal operating point. Initial voltage setting avoids cold start shocks, incremental perturbation ensures smooth loading of control parameters, and steady-state determination guarantees precise anchoring of the operating point. This sequence integrates the separate initialization, scanning, and locking stages into a continuous adaptive process, eliminating power interruptions caused by mode switching. The technical value is reflected on two levels: electrically, it reduces startup energy loss by 80%, and control-wise, it compresses convergence time to one-third of conventional solutions.

[0078] Accordingly, please refer to Figure 2 A second aspect of the present invention provides a DC-side coupling device for a photovoltaic-storage system with integrated MPPT functionality, which controls the DC side of the photovoltaic-storage system based on the aforementioned DC-side coupling method with integrated MPPT functionality, including: Signal superposition module 1 is used to inject a controlled voltage disturbance signal into the DC bus. The controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value. The slope calculation module 2 is used to acquire the voltage ripple data of the DC bus and the output current of the photovoltaic array in real time, and calculate the dynamic slope characteristic based on the voltage ripple data and the output current of the photovoltaic array. The dynamic slope characteristic represents the instantaneous rate of change of the output power of the photovoltaic array with respect to the DC bus voltage. Voltage adjustment module 3 is used to dynamically adjust the voltage reference value of the DC bus based on dynamic slope characteristics. The voltage tracking module 4 is used to adjust the charging and discharging power of the energy storage battery so that the actual voltage of the DC bus tracks the adjusted voltage reference value of the DC bus, thereby achieving maximum power point tracking of the photovoltaic array. At the same time, it achieves dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power through closed-loop regulation of the DC bus voltage.

[0079] Accordingly, a third aspect of the present invention provides an electronic device, including: at least one processor; and a memory connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to cause the at least one processor to perform the above-described photovoltaic energy storage system DC-side coupling method with integrated MPPT function.

[0080] Accordingly, a fourth aspect of the present invention provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the above-described method for DC-side coupling of an optical storage system with integrated MPPT functionality.

[0081] This invention aims to protect a DC-side coupling method and apparatus for a photovoltaic-storage system with integrated MPPT (Maximum Power Point Tracking) function. The DC-side coupling method includes the following steps: injecting a controlled voltage disturbance signal into the DC bus, where the controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value; acquiring the DC bus voltage ripple data and the photovoltaic array output current in real time; calculating a dynamic slope characteristic based on the voltage ripple data and the photovoltaic array output current, where the dynamic slope characteristic represents the instantaneous rate of change of the photovoltaic array output power with respect to the DC bus voltage; dynamically adjusting the DC bus voltage reference value based on the dynamic slope characteristic; and adjusting the charging and discharging power of the energy storage battery to ensure that the actual DC bus voltage tracks the adjusted DC bus voltage reference value, thereby achieving maximum power point tracking of the photovoltaic array. Simultaneously, the closed-loop regulation of the DC bus voltage achieves a dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power. The above technical solution has the following advantages: 1. By eliminating the independent controller and dedicated MPPT converter on the photovoltaic side, and retaining only the unidirectional conduction element to achieve direct connection between the photovoltaic array and the DC bus, and using the bidirectional power converter to locally complete disturbance injection, ripple feature extraction and slope calculation, the multiple power conversion links and communication module dependencies in the traditional scheme are fundamentally eliminated, significantly reducing system manufacturing costs and maintenance complexity, and improving hardware reliability. 2. Based on the dynamic slope characteristic quantity, the system autonomously decides the adjustment direction of the bus voltage reference value. Through the closed-loop regulation of energy storage charging and discharging power, it realizes the photovoltaic maximum power point tracking and the dynamic matching of photovoltaic and energy storage power, completely eliminating the dependence on the communication link. This ensures that the system autonomously maintains power balance under complex operating conditions such as sudden irradiation and load step, and greatly enhances dynamic response capability and operational stability. 3. By integrating the disturbance progressive enhancement mechanism during the startup phase, the threshold / step size adaptive algorithm under steady state, and the fault protection strategy, a full-cycle control closed loop covering initialization, steady-state operation, and abnormal states is formed. This effectively overcomes the difficulties of startup under low irradiance, environmental noise interference, and voltage instability risks, ensuring that the system maintains efficient and safe energy coupling under a wide range of operating conditions.

[0082] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0083] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0084] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0085] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A DC-side coupling method for a photovoltaic-storage system integrating MPPT functionality, characterized in that, Includes the following steps: A controlled voltage disturbance signal is injected into the DC bus, wherein the controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value; The voltage ripple data of the DC bus and the output current of the photovoltaic array are acquired in real time. Based on the voltage ripple data and the output current of the photovoltaic array, a dynamic slope characteristic is calculated. The dynamic slope characteristic represents the instantaneous rate of change of the output power of the photovoltaic array with respect to the DC bus voltage. The voltage reference value of the DC bus is dynamically adjusted based on the dynamic slope characteristic. The charging and discharging power of the energy storage battery is adjusted so that the actual voltage of the DC bus tracks the adjusted reference voltage value of the DC bus, thereby achieving maximum power point tracking of the photovoltaic array. At the same time, the closed-loop regulation of the DC bus voltage achieves a dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power.

2. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to claim 1, characterized in that, The injection of a controlled voltage disturbance signal into the DC bus includes: A periodic AC component is generated, the amplitude of which is within a preset range of the rated voltage of the DC bus. The periodic AC component is superimposed on the DC bus voltage reference value of the current detection period to form the superimposed voltage reference value; A voltage modulation command is generated based on the superimposed voltage reference value; The bidirectional power converter performs pulse width modulation according to the voltage modulation command, generating the controlled voltage disturbance signal on the DC bus.

3. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to claim 1, characterized in that, The calculation of the dynamic slope characteristic based on the voltage ripple data and the output current of the photovoltaic array includes: Within a preset time interval of the controlled voltage disturbance signal, the DC bus voltage values ​​of two adjacent detection cycles are acquired; The output current values ​​of the photovoltaic array in two adjacent detection cycles are acquired simultaneously. Calculate the change in photovoltaic array output power between two adjacent detection cycles; The dynamic slope characteristic is obtained by dividing the change in output power of the photovoltaic array by the change in DC bus voltage.

4. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to claim 3, characterized in that, The dynamic slope feature quantity The calculation formula is: ； ; in, For the first The output power of the photovoltaic array in each detection cycle For the first The output power of the photovoltaic array in each detection cycle For the first DC bus voltage value for each detection cycle For the first DC bus voltage value for each detection cycle For the first The output current value of the photovoltaic array in each detection cycle. This is the detection cycle number. This is the serial number of the previous testing cycle.

5. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to claim 1, characterized in that, The dynamic adjustment of the DC bus voltage reference value based on the dynamic slope characteristic includes: Determine whether the dynamic slope feature is within a preset slope threshold range; If the dynamic slope characteristic is within the preset slope threshold range, the current DC bus voltage reference value remains unchanged. If the dynamic slope feature is greater than the upper limit of the preset slope threshold range, then the adjustment direction of the DC bus voltage reference value is determined to be positive increase; If the dynamic slope feature is less than the lower limit of the preset slope threshold range, then the adjustment direction of the DC bus voltage reference value is determined to be a negative decrease. Based on the adjustment direction and preset step size, update the current DC bus voltage reference value and reset the current adjustment step size.

6. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to claim 5, characterized in that, Before determining whether the dynamic slope feature is within a preset threshold range, the method further includes: Obtain the calibration open-circuit voltage parameters of the photovoltaic modules in the photovoltaic array; The theoretical slope critical value is calculated based on the calibrated open-circuit voltage parameters and the nominal maximum power point voltage of the photovoltaic array. Multiplying the theoretical slope critical value by a preset attenuation factor yields the absolute values ​​of the upper limit and lower limit of the preset slope threshold interval. The upper limit of the preset slope threshold interval is the absolute value, and the lower limit of the preset slope threshold interval is the opposite of the absolute value.

7. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to claim 5, characterized in that, Before determining whether the dynamic slope feature is within a preset threshold range, the method further includes: Obtain the amplitude of the currently controlled voltage disturbance signal; The amplitude of the controlled voltage disturbance signal is multiplied by a preset proportional coefficient to obtain the basic adjustment step size; Based on the difference between the absolute value of the dynamic slope feature and the upper limit or lower limit of the preset slope threshold interval, the basic adjustment step size is linearly scaled, and the scaled step size value is used as the current adjustment step size for positive increase or negative decrease.

8. The DC-side coupling method for a photovoltaic-storage system with integrated MPPT function according to any one of claims 1-7, characterized in that, Before injecting the controlled voltage disturbance signal into the DC bus, the method further includes: The preset initial voltage is used as the reference value for the DC bus voltage; Inject a controlled voltage disturbance signal with increasing amplitude until the DC bus voltage reference value reaches the rated amplitude; When the dynamic slope feature is detected to be within the preset slope threshold range for three consecutive detection cycles, the start-up is completed and the system enters steady-state operation.

9. A DC-side coupling device for a photovoltaic energy storage system with integrated MPPT function, characterized in that, The DC-side coupling method for a photovoltaic-storage system based on the integrated MPPT function of any one of claims 1-8 controls the DC side of the photovoltaic-storage system, including: A signal superposition module is used to inject a controlled voltage disturbance signal into the DC bus, wherein the controlled voltage disturbance signal is a periodic AC component superimposed on the DC bus voltage reference value; The slope calculation module is used to acquire the voltage ripple data of the DC bus and the output current of the photovoltaic array in real time, and calculate the dynamic slope characteristic based on the voltage ripple data and the output current of the photovoltaic array. The dynamic slope characteristic represents the instantaneous rate of change of the output power of the photovoltaic array with respect to the DC bus voltage. A voltage adjustment module is used to dynamically adjust the voltage reference value of the DC bus based on the dynamic slope characteristic. The voltage tracking module is used to adjust the charging and discharging power of the energy storage battery so that the actual voltage of the DC bus tracks the adjusted voltage reference value of the DC bus, thereby achieving maximum power point tracking of the photovoltaic array. At the same time, it achieves dynamic balance between photovoltaic power generation and energy storage battery charging and discharging power through closed-loop regulation of the DC bus voltage.

10. An electronic device, comprising: At least one processor; And a memory connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to cause the at least one processor to perform the DC-side coupling method of the optical storage system with integrated MPPT function as described in any one of claims 1-8.

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