Power-grid-friendly light-storage direct-current integrated grid-connected control method and device

Abstract

The invention discloses a power grid friendly light storage direct current integrated grid-connected control method and device. The method comprises the following steps: acquiring a power grid dispatching instruction, a common connection point voltage / frequency deviation, the maximum power of a photovoltaic unit, the charge state of an energy storage unit and a power limit value in real time; calculating a total active / reactive power target value required to be injected into the power grid by the grid-connected converter based on the power grid dispatching instruction and the common connection point voltage / frequency deviation; generating a photovoltaic power / energy storage power dynamic adjustment coefficient in real time according to the power grid frequency deviation amplitude, the voltage out-of-limit grade and the charge state of the energy storage unit, and decomposing the total active power target value into photovoltaic unit / energy storage unit instruction power; adjusting the direct-current bus voltage based on the total active / reactive power target value in a grid-connected converter control layer to realize a power grid supporting function; in a local unit control layer, photovoltaic unit instruction power is tracked through a photovoltaic unit DC / DC converter, and energy storage unit instruction power is tracked through an energy storage unit bidirectional DC / DC converter.

Description

A grid-friendly photovoltaic-storage-DC integrated grid-connected control method and device Technical Field

[0001] This invention relates to the field of power grid control technology, and in particular to a grid-friendly photovoltaic-storage-DC integrated grid-connected control method and device. Background Technology

[0002] With the accelerated global energy transition, photovoltaic (PV) power generation, as a core representative of clean and renewable energy, has seen its penetration rate in the power system continue to rise. However, PV output exhibits significant intermittency and volatility, and its large-scale direct grid connection can impact the voltage, frequency stability, and power quality of the power grid, even leading to curtailment issues. To mitigate PV fluctuations and improve system dispatchability, configuring energy storage systems (ESS) to form a "PV-storage combined system" has become an industry consensus. Traditional PV-storage grid connection schemes typically employ distributed AC-side access or simple DC-side parallel connection, with PV and energy storage units independently connected to the AC bus via their respective converters. This structure suffers from problems such as sluggish power coordination response, complex control hierarchy, and low DC power reuse efficiency, making it difficult to meet the stringent requirements of the power grid for rapid frequency regulation, voltage regulation, and precise tracking of dispatch commands in scenarios with a high proportion of renewable energy.

[0003] Current mainstream photovoltaic-storage coordinated control strategies mainly focus on long-term economic dispatch (such as charge / discharge plans based on day-ahead forecasts) or simple power allocation under single abnormal operating conditions (such as sudden drops in grid frequency). These methods often rely on centralized energy management systems (EMS) for optimization calculations at the second level or longer, making it difficult to achieve dynamic power fine-tuning at the millisecond to hundred-millisecond level. Especially when the grid experiences short-term disturbances (such as voltage dips or frequency fluctuations) or frequent adjustments to dispatch commands, existing strategies lack the real-time coordination capability between photovoltaic maximum power point (MPP) tracking and energy storage state of charge (SOC) constraints. This can easily lead to excessive photovoltaic curtailment, overcharging / over-discharging of energy storage, or delayed grid support response, limiting the system's ability to actively support the grid.

[0004] Furthermore, in conventional schemes, the DC bus voltage is typically controlled by a single point, either the energy storage converter or the grid-connected inverter, lacking a multi-source coordinated voltage interaction mechanism. When photovoltaic output changes abruptly or a grid fault occurs, the DC bus voltage may become unstable, affecting grid-connected power quality and even triggering protection actions. Simultaneously, the power command allocation between photovoltaic and energy storage units often employs static proportional or priority strategies, failing to fully consider the dynamic coupling relationship between the real-time grid operating status (such as frequency deviation amplitude and voltage over-limit depth) and the energy storage SOC health. This results in the system's regulation potential not being optimally released, reducing the overall utilization rate and grid friendliness of the photovoltaic-energy storage system. Summary of the Invention

[0005] The purpose of this invention is to provide a grid-friendly photovoltaic-storage-DC integrated grid-connected control method and device. By dynamically adjusting the coefficient to couple the grid state and the energy storage state of charge in real time, the system can achieve adaptive and coordinated allocation of photovoltaic and energy storage power commands. This allows the system to prioritize the use of energy storage to quickly smooth grid disturbances under high-proportion renewable energy penetration, while maximizing photovoltaic consumption.

[0006] To address the aforementioned technical problems, a first aspect of this invention provides a grid-friendly photovoltaic-storage-DC integrated grid-connected control method. The photovoltaic unit is connected to the DC bus via a DC / DC converter, and the energy storage unit is connected via a bidirectional DC / DC converter, forming an integrated power aggregation node on the DC side. The grid-connected control method includes the following steps: real-time acquisition of grid dispatch commands, point-of-compatibility voltage / frequency deviation, maximum power output of the photovoltaic unit, state of charge of the energy storage unit, and power limits; based on the grid dispatch commands and the point-of-compatibility voltage / frequency deviation, calculating the total active / reactive power that the grid-connected converter needs to inject into the grid. The system generates dynamic adjustment coefficients for photovoltaic power and energy storage power in real time based on the grid frequency deviation amplitude, voltage over-limit level, and energy storage unit state of charge. The total active power target value is decomposed into photovoltaic unit command power and energy storage unit command power. At the grid-connected converter control layer, the DC bus voltage is adjusted based on the total active / reactive power target value to achieve grid support functionality. At the photovoltaic unit control layer and energy storage unit control layer, the photovoltaic unit DC / DC converter tracks the photovoltaic unit command power, and the energy storage unit bidirectional DC / DC converter tracks the corrected energy storage unit command power, achieving millisecond-level power response.

[0007] Furthermore, the step of generating dynamic adjustment coefficients for photovoltaic power and energy storage power in real time based on the grid frequency deviation amplitude, voltage over-limit level, and energy storage unit state of charge includes: mapping the grid frequency deviation amplitude to a preset frequency support demand range, mapping the voltage over-limit level to a preset voltage support demand range, and mapping the energy storage unit state of charge to a preset safe operating range for the state of charge; assigning real-time power adjustment weights to the photovoltaic unit and the energy storage unit based on the coupling result of the frequency support demand range, voltage support demand range, and safe operating range for the state of charge; normalizing the power adjustment weights of the photovoltaic unit to generate dynamic adjustment coefficients for photovoltaic power; and normalizing the power adjustment weights of the energy storage unit to generate dynamic adjustment coefficients for energy storage power, ensuring that the sum of the two coefficients is a constant value and dynamically changes with the grid / energy storage state.

[0008] Furthermore, the real-time power regulation weight allocation for photovoltaic (PV) units and energy storage units based on the coupling results of the frequency support demand interval, voltage support demand interval, and state-of-charge (SOC) safe operating interval includes: determining the comprehensive grid support demand level based on preset level weights of the frequency support demand interval and voltage support demand interval, and generating an energy storage regulation safety margin factor according to the boundary of the SOC safe operating interval; dynamically coupling the comprehensive grid support demand level and the energy storage regulation safety margin factor, and allocating the power regulation weights of PV units and energy storage units in real time according to the coupling results; increasing the power regulation weight of energy storage units when the comprehensive grid support demand level increases, and decreasing the power regulation weight of energy storage units when the energy storage regulation safety margin factor decreases; and applying dynamic smoothing constraints to the allocated power regulation weights to ensure that the weight ratio of PV units and energy storage units changes continuously with the coupling results and that the total weight remains constant.

[0009] Furthermore, the step of adjusting the DC bus voltage based on the total active / reactive power target value to achieve grid support function in the grid-connected converter control layer includes: calculating the DC bus voltage reference value in real time based on the total active power target value and the voltage control requirements in the grid dispatching instructions, and superimposing the compensation component of the point of common coupling voltage deviation; inputting the deviation between the DC bus voltage reference value and the measured DC bus voltage into the outer loop voltage controller, outputting the grid-connected converter active current reference value, and simultaneously converting the total reactive power target value into a reactive current reference value; dynamically adjusting the reactive current reference value according to the point of common coupling voltage over-limit level, prioritizing the increase of reactive power output when the grid voltage drops, and simultaneously limiting the active current reference value to meet the low voltage ride-through requirements; and generating a pulse width modulation signal through the current inner loop tracking control based on the active current reference value and the reactive current reference value to drive the grid-connected converter to inject the target power into the grid while maintaining the DC bus voltage stability.

[0010] Furthermore, the step of dynamically adjusting the reactive current reference value according to the voltage overshoot level of the point of common coupling (PCC) to prioritize increasing reactive power output when the grid voltage drops, while simultaneously limiting the active current reference value to meet low-voltage ride-through requirements, includes: mapping the PCC voltage overshoot level to a preset reactive power support strength range to generate a dynamic reactive power compensation coefficient, with a higher coefficient for a greater voltage drop depth; multiplying the total reactive power target value by the dynamic reactive power compensation coefficient to generate an enhanced reactive current reference value, wherein the enhanced reactive current reference value does not exceed the maximum allowable output current of the grid-connected converter; calculating the active current limit value in real time based on the enhanced reactive current reference value and the maximum allowable output current of the grid-connected converter, thereby constraining the active current reference value to the limit range; and reversing the total active power target value based on the limit result of the active current reference value, triggering the energy storage unit to prioritize absorbing the photovoltaic power surplus caused by the active power limit.

[0011] Furthermore, the step of generating a pulse width modulation signal through current inner loop tracking control based on active and reactive current reference values ​​to drive the grid-connected converter to inject target power into the grid while maintaining DC bus voltage stability includes: adjusting the proportional gain and integral time constant of the current inner loop controller in real time based on the harmonic distortion rate of the point of common coupling voltage and the grid impedance change rate; superimposing a virtual impedance compensation term in the current inner loop control, the virtual impedance compensation term dynamically adjusting its amplitude according to the grid frequency deviation direction to suppress grid current harmonic oscillations; adopting a decoupled control structure in a rotating coordinate system to independently track the active and reactive current reference values, wherein the decoupling term is dynamically corrected according to the grid voltage phase; superimposing the voltage command output by the decoupled control with the DC bus voltage ripple compensation amount, generating an anti-disturbance pulse width modulation signal through space vector modulation, and driving the grid-connected converter to stably output the target power under grid disturbances.

[0012] Further, the step of tracking the commanded power of the photovoltaic unit through the photovoltaic unit DC / DC converter and tracking the corrected commanded power of the energy storage unit through the bidirectional DC / DC converter of the energy storage unit includes: dynamically adjusting the search boundary of the maximum power point tracking algorithm based on the commanded power of the photovoltaic unit and the maximum power that the photovoltaic unit can generate, so that the photovoltaic DC / DC converter prioritizes tracking the commanded power and switches to maximum power point operation when the commanded power exceeds the range that can be generated; determining the charging and discharging mode according to the sign of the corrected commanded power of the energy storage unit, and dynamically constraining the charging current based on the upper limit of the state of charge and temperature parameters in the charging mode, and in the discharging mode... The formula is based on the state-of-charge limit and aging factor to dynamically constrain the discharge power; adaptive hysteresis widths are configured for the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter respectively. The adaptive hysteresis widths are adjusted in real time according to the DC bus voltage fluctuation rate and the command power change rate to achieve a dynamic balance between switching frequency and power tracking accuracy; the output signal of the dynamic hysteresis control is superimposed with the DC bus voltage ripple feedforward compensation to generate an anti-disturbance pulse drive signal, which drives the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to track the target power in milliseconds under grid disturbances, while suppressing switching transient impacts.

[0013] Furthermore, configuring adaptive hysteresis widths for the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter respectively includes: real-time acquisition of the DC bus voltage fluctuation rate and the commanded power change rate, while simultaneously acquiring the current switching frequency and power tracking error of the photovoltaic unit / energy storage unit; mapping the DC bus voltage fluctuation rate to a preset hysteresis width anti-interference range, and mapping the commanded power change rate to a preset hysteresis width response range, generating an initial hysteresis width reference value based on the coupling result of the two ranges; performing bidirectional elastic correction on the initial hysteresis width reference value according to the ratio of the current switching frequency to the preset maximum allowable switching frequency and the ratio of the power tracking error to the preset error threshold, increasing the hysteresis width to reduce losses when the switching frequency ratio increases, and decreasing the hysteresis width to improve accuracy when the tracking error ratio increases; inputting the corrected hysteresis width reference value into the hysteresis comparators of the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter respectively, driving the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to achieve dynamic balanced power tracking respectively.

[0014] Accordingly, a second aspect of the present invention provides a grid-friendly photovoltaic-storage-DC integrated grid-connected control device, characterized in that, based on the above-mentioned grid-friendly photovoltaic-storage-DC integrated grid-connected control method, the photovoltaic unit is connected to the DC bus through a DC / DC converter and the energy storage unit is connected to the DC bus through a bidirectional DC / DC converter, forming an integrated power aggregation node on the DC side. The grid-connected control device includes: a data acquisition module, which is used to collect in real time grid dispatch instructions, point of common coupling voltage / frequency deviation, maximum power output of the photovoltaic unit, state of charge of the energy storage unit, and power limit; and a data calculation module, which is used to calculate the total active power / voltage / frequency deviation that the grid-connected converter needs to inject into the grid based on the grid dispatch instructions and the point of common coupling voltage / frequency deviation. The system comprises: a reactive power target value; a coefficient adjustment module, which generates dynamic adjustment coefficients for photovoltaic power and energy storage power in real time based on grid frequency deviation, voltage over-limit level, and energy storage unit state of charge, and decomposes the total active power target value into photovoltaic unit command power and energy storage unit command power; a first control module, which adjusts the DC bus voltage based on the total active / reactive power target value at the grid-connected converter control layer to achieve grid support function; and a second control module, which tracks the photovoltaic unit command power through the photovoltaic unit DC / DC converter and tracks the corrected energy storage unit command power through the bidirectional DC / DC converter of the energy storage unit at the photovoltaic unit control layer and the energy storage unit control layer, achieving millisecond-level power response.

[0015] 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 grid-friendly photovoltaic-storage-DC integrated grid-connected control method.

[0016] 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 grid-friendly photovoltaic-storage-DC integrated grid-connected control method.

[0017] The above-mentioned technical solution of the present invention has the following beneficial technical effects: 1. By using the grid state-energy storage state dynamic coupling mechanism, the grid frequency deviation amplitude, voltage over-limit level and energy storage SOC safety boundary are integrated in real time to generate dynamic adjustment coefficients for photovoltaic and energy storage, breaking through the limitations of traditional static allocation strategies; the grid support demand comprehensive level is used to quantify the grid urgency, and the energy storage adjustment safety margin factor is combined to ensure energy storage safety. The dynamic coupling of the two realizes the adaptive allocation of power adjustment weight: when the grid frequency drops sharply or the voltage depth exceeds the limit, the power weight of energy storage is automatically increased to quickly respond to the frequency regulation demand, while the weight of energy storage is reduced when the energy storage SOC is close to the limit to avoid overcharging / over-discharging; dynamic smoothing constraints ensure that the power allocation is continuous and shock-free, solving the power oscillation problem caused by weight jumps in traditional schemes; finally, under grid disturbances, the photovoltaic-energy storage system can optimize the power allocation ratio in seconds, taking into account grid support and energy storage life, and the system adjustment potential utilization rate is improved by more than 30%; 2. Based on the grid-connected converter's active support strategy, the system's low-voltage ride-through performance is improved through DC bus voltage adaptive adjustment and reactive power priority output mechanism. Specifically: the DC bus voltage reference value is superimposed with PCC voltage deviation compensation, enabling the DC side to actively respond to grid voltage fluctuations; the dynamic reactive power compensation coefficient increases reactive power output in real time according to the voltage drop depth (e.g., prioritizing reactive power generation when the voltage drops to 0.5 pu), while limiting active current to prevent converter overcurrent; virtual impedance compensation and harmonic adaptive control work together to suppress grid current oscillations, ensuring stable operation during faults; ensuring that when the grid voltage drops to 0.5 pu, the reactive power support response time is <20ms, active power recovers smoothly, 100% meeting the latest grid connection standards for low-voltage ride-through, and avoiding unplanned grid disconnection; 3. Through local converter adaptive hysteresis control and power-voltage coordinated disturbance rejection design, high-speed and precise response of the photovoltaic-storage unit is achieved: the photovoltaic DC / DC dynamically adjusts the MPPT boundary, prioritizes commanded power tracking, and seamlessly switches to MPPT mode when the limit is exceeded, reducing curtailment; the energy storage charging and discharging integrates SOC, temperature, and aging factors to dynamically constrain current / power, extending battery life; the hysteresis width elastic correction algorithm balances switching frequency and tracking accuracy in real time according to the bus voltage fluctuation rate and command change rate, reducing switching losses by 15%; and ripple feedforward compensation is superimposed to offset the impact of grid disturbances. Ultimately, under scenarios of dispatch command step or sudden change in illumination, the system power tracking error is <2%, DC bus voltage fluctuation is controlled within ±1%, and power tracking delay is <5ms, significantly improving power quality. Attached Figure Description

[0018] Figure 1 is a flowchart of the grid-friendly photovoltaic-storage-DC integrated grid-connected control method provided in an embodiment of the present invention; Figure 2 is a block diagram of the grid-friendly photovoltaic-storage-DC integrated grid-connected control device provided in an embodiment of the present invention.

[0019] Attached reference numerals: 1. Data acquisition module, 2. Data calculation module, 3. Coefficient adjustment module, 4. First control module, 5. Second control module. Detailed Implementation

[0020] 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.

[0021] Referring to Figure 1, the first aspect of this invention provides a grid-friendly photovoltaic-storage-DC integrated grid-connected control method. The photovoltaic unit is connected to the DC bus through a DC / DC converter and the energy storage unit is connected to the DC bus through a bidirectional DC / DC converter, forming an integrated power aggregation node on the DC side. The grid-connected control method includes the following steps: Step S100, real-time acquisition of grid dispatch instructions, voltage / frequency deviation at the point of common coupling, maximum power output of the photovoltaic unit, state of charge of the energy storage unit, and power limit.

[0022] By synchronously collecting real-time data from a multi-source sensing system, including grid dispatch commands (including active / reactive power setpoints issued by the upper-level energy management system), voltage / frequency deviation at the point of common coupling (real-time monitoring of the instantaneous offset of the voltage amplitude and frequency at the grid connection point relative to the rated value), maximum power output of photovoltaic units (dynamically calculated based on the current light intensity, temperature, and IV characteristic curves of the photovoltaic array), state of charge of energy storage units (precisely quantifying the SOC value of the battery's current remaining capacity), and power limits of energy storage units (instantaneous power safety boundaries determined by comprehensively considering battery temperature, aging degree, and charge / discharge rate), a full-dimensional real-time database covering grid dispatch requirements, new energy output characteristics, and energy storage operation constraints is constructed, providing a data foundation for subsequent collaborative control.

[0023] Step S200: Based on the grid dispatch instructions and the voltage / frequency deviation at the point of common coupling, calculate the target value of the total active / reactive power that the grid-connected converter needs to inject into the grid.

[0024] Based on the collected grid dispatch instructions and the voltage / frequency deviation at the point of common coupling, a dual-path fusion calculation is performed: the active power target value is generated by adding the active power setpoint in the dispatch instruction to the real-time frequency regulation compensation component of the frequency deviation (e.g., increasing active power output demand according to a preset ratio when there is a positive frequency deviation), and the reactive power target value is generated by adding the reactive power setpoint in the dispatch instruction to the voltage regulation compensation component of the voltage deviation (e.g., increasing capacitive reactive power support demand when there is a negative voltage deviation); finally, the total active / reactive power target value that the grid-connected converter needs to inject into the grid is output, realizing the dynamic unification of grid dispatch instruction execution and grid active support function.

[0025] Step S300: Based on the grid frequency deviation amplitude, voltage over-limit level and energy storage unit charge state, generate the photovoltaic power dynamic adjustment coefficient and the energy storage power dynamic adjustment coefficient in real time, and decompose the total active power target value into photovoltaic unit command power and energy storage unit command power.

[0026] The grid frequency deviation is mapped to preset frequency regulation demand levels (e.g., ±0.1Hz for normal zone, ±0.5Hz for emergency zone), voltage over-limit levels are mapped to voltage regulation demand levels (e.g., ±5% for warning level, ±10% for fault level), and energy storage state of charge is mapped to safety margin range (e.g., charging margin is zero when SOC>90%, discharging margin is zero when SOC<20%). A multi-dimensional interval coupling algorithm generates dynamic adjustment coefficients for photovoltaic power and energy storage power in real time, strictly limiting their sum to always be 1. Based on these two coefficients, the total active power target value is decomposed into photovoltaic unit command power (total active power target value × photovoltaic coefficient) and energy storage unit command power (total active power target value × energy storage coefficient), breaking through the limitations of traditional static proportional allocation and achieving a dynamic real-time balance between grid emergency support needs and energy storage operational safety.

[0027] In step S400, at the grid-connected converter control layer, the DC bus voltage is adjusted based on the total active / reactive power target value to achieve grid support function.

[0028] At the grid-connected converter control layer, the DC bus voltage reference value is dynamically calculated based on the total active power target value (generated according to the power-voltage transfer function), and a real-time feedforward compensation component of the point of common coupling voltage deviation is superimposed (e.g., raising the DC reference voltage by 2% when the voltage drops by 10%). The deviation between the measured DC voltage and the reference value is converted into an active current reference value through the DC voltage outer loop controller, and the total reactive power target value is converted into a reactive current reference value according to the grid voltage base value. When a severe voltage drop at the point of common coupling is detected (e.g., below 0.8 pu), the low voltage ride-through mode is activated: the reactive current output is increased proportionally to the voltage drop depth (up to the converter tolerance), while the active current reference value is limited to prevent overcurrent. Finally, a decoupled control structure in a rotating coordinate system (independent control of the dq axis) is superimposed with a virtual impedance compensation term to drive the grid-connected converter to stably inject the target power and maintain the DC bus voltage fluctuation rate within ±1%.

[0029] In step S500, at the photovoltaic unit control layer and the energy storage unit control layer, the photovoltaic unit DC / DC converter tracks the commanded power of the photovoltaic unit, and the bidirectional DC / DC converter of the energy storage unit tracks the corrected commanded power of the energy storage unit, thereby achieving millisecond-level power response.

[0030] At the local control layer, the photovoltaic unit's DC / DC converter prioritizes tracking the photovoltaic command power issued in step S300 (forcing the operating point to shift to the command value) through a modified maximum power point tracking algorithm. When the command power exceeds the maximum photovoltaic power output, it automatically switches to the traditional MPPT mode to maximize the utilization of solar resources. The energy storage unit's bidirectional DC / DC converter tracks the command power corrected by multiple constraints: in charging mode, it limits the current based on the upper limit threshold of SOC (e.g., 95%) and battery temperature in real time (reducing the charging current by 5% for every 10°C increase in temperature); in discharging mode, it dynamically limits the power based on the lower limit threshold of SOC (e.g., 15%) and battery aging factor (reducing the discharge power by 2% for every 100 cycles). Through hysteresis width adaptive control (adjusting the hysteresis comparator threshold in real time according to the DC bus voltage fluctuation rate and the command power change rate) superimposed with DC ripple voltage feedforward compensation, it suppresses the power tracking deviation caused by grid disturbances and ensures that the power response delay of both photovoltaic and energy storage is less than 5 milliseconds.

[0031] The aforementioned grid-friendly photovoltaic-storage-DC integrated grid-connected control method establishes a global optimization foundation through real-time collaborative decision-making based on multi-source data. The hierarchical control architecture achieves efficient division of labor between the grid-connected layer (S400) and the local layer (S500), while the dynamic weight allocation mechanism (S300) ensures a dynamic balance between grid support needs and energy storage security. During grid frequency / voltage fluctuations, the photovoltaic-storage power allocation ratio is optimized at the second level (e.g., the energy storage coefficient automatically rises to 0.8 for rapid frequency adjustment when the frequency drops sharply). The grid-connected converter layer enhances grid stability through active voltage feedforward and fault ride-through strategies (reactive power support response <20ms during voltage dips). The local control layer achieves millisecond-level accurate power tracking (error <2%) by relying on adaptive hysteresis control and multi-constraint management, forming an integrated closed loop of "grid status perception - global power allocation - rapid equipment execution," systematically solving the core defects of traditional solutions such as slow response, poor coordination, and weak anti-interference capability.

[0032] Further, step S300, which generates dynamic adjustment coefficients for photovoltaic power and energy storage power in real time based on the grid frequency deviation amplitude, voltage over-limit level, and energy storage unit state of charge, includes: step S310, mapping the grid frequency deviation amplitude to a preset frequency support demand range, mapping the voltage over-limit level to a preset voltage support demand range, and mapping the energy storage unit state of charge to a preset safe operating range for the state of charge.

[0033] The grid frequency deviation is mapped to a preset frequency support demand range (e.g., ±0.1Hz for normal level, ±0.5Hz for emergency level), and the voltage over-limit level is mapped to a preset voltage support demand range (e.g., ±5% for warning level, ±10% for fault level). At the same time, the energy storage state of charge is mapped to a preset safe operating range of state of charge (e.g., SOC 20%-90% is the safe zone, discharge safety level is zero when SOC<20%, and charging safety level is zero when SOC>90%). Continuous operating parameters are converted into discrete standardized support demand levels and safety levels, providing a unified quantitative input for dynamic weight allocation.

[0034] Step S320: Based on the coupling results of the frequency support demand range, voltage support demand range, and state-of-charge safe operation range, real-time power regulation weights are assigned to the photovoltaic unit and the energy storage unit.

[0035] Based on the coupling results of the frequency support demand range and the voltage support demand range (integrated into a comprehensive grid support demand level according to preset weight coefficients, such as frequency weight 0.6 + voltage weight 0.4), combined with the adjustment safety margin factor generated by the safe operation range of energy storage charge state (such as the factor being 1.0 when SOC is 40%-80%, and linearly decreasing to 0.2 at the boundary), the real-time power adjustment weights of photovoltaic and energy storage are dynamically allocated: when the comprehensive grid support demand level increases, the energy storage weight is increased (such as energy storage weight +0.15 for each level increase), and when the energy storage safety margin factor decreases, the energy storage weight is decreased (such as energy storage weight -0.05 for each 0.1 decrease in the factor). The photovoltaic weight changes synchronously and complementaryly, and the sum remains constant. A first-order inertial filter is used to ensure a continuous and smooth transition of the weight ratio.

[0036] Step S330: Normalize the power adjustment weights of the photovoltaic units to generate a dynamic adjustment coefficient for photovoltaic power. Normalize the power adjustment weights of the energy storage units to generate a dynamic adjustment coefficient for energy storage power, ensuring that the sum of the two coefficients is a constant value and dynamically changes with the grid / energy storage status.

[0037] The power adjustment weights of photovoltaic (PV) and energy storage are normalized to generate dynamic adjustment coefficients for PV power (PV weight / total weight) and energy storage power (energy storage weight / total weight), and the sum of the two coefficients is forcibly constrained to always be 1. The coefficients are updated in real time according to the grid frequency / voltage status and energy storage SOC (e.g., when the frequency drops by 0.4Hz and SOC=50%, the energy storage coefficient rises to 0.7, and when SOC=25%, it drops to 0.3), ensuring that the total active power target value is fully decomposed to PV and energy storage units.

[0038] A unified decision-making benchmark is established through parameter standardization mapping. The dynamic coupling of grid emergency demand and energy storage safety margin enables adaptive weight allocation. Normalization coefficient constraints ensure accurate power decomposition. When the grid frequency drops sharply, the energy storage regulation ratio is automatically increased (e.g., the energy storage coefficient reaches 0.8 when the deviation is 0.5Hz) to quickly support the grid. When the energy storage SOC is close to the boundary, its weight is reduced to avoid overcharging / over-discharging. The weight smooth transition mechanism eliminates power command jumps, forming a dynamic allocation strategy that takes into account both grid response speed and energy storage safety.

[0039] Furthermore, in step S320, based on the coupling results of the frequency support demand interval, voltage support demand interval, and state-of-charge safe operating interval, real-time power regulation weights are assigned to the photovoltaic unit and the energy storage unit, including: step S321, determining the comprehensive level of grid support demand based on the preset level weights of the frequency support demand interval and the voltage support demand interval, and generating an energy storage regulation safety margin factor according to the boundary of the state-of-charge safe operating interval.

[0040] Based on the preset level weights of frequency support demand range and voltage support demand range (e.g., frequency demand weight accounts for 60% and voltage demand weight accounts for 40%), a quantitative comprehensive level of grid support demand is generated by weighted fusion (the higher the value, the more severe the urgency of grid frequency / voltage anomalies); at the same time, an energy storage regulation safety margin factor is generated according to the boundary of the safe operating range of state of charge (e.g., 20% and 90% of SOC are safe boundaries) (the factor is 1.0 in the range of 40%-80% of SOC, and linearly decreases to 0.2 when approaching the 20% or 90% boundary). This safety margin factor represents the upper limit of the power capacity of energy storage that can safely participate in regulation.

[0041] Step S322: Dynamically couple the overall grid support demand level with the energy storage regulation safety margin factor, and allocate the power regulation weights of photovoltaic units and energy storage units in real time according to the coupling result. When the overall grid support demand level increases, the power regulation weight of energy storage units is increased; when the energy storage regulation safety margin factor decreases, the power regulation weight of energy storage units is decreased.

[0042] The overall grid support demand level is dynamically coupled with the energy storage regulation safety margin factor (e.g., through product or weighted summation). Based on the coupling result, the power regulation weights of photovoltaic and energy storage are allocated in real time: when the overall grid support demand level increases (e.g., a sudden drop in frequency of 0.5Hz causes the level to rise to the highest level), the weight of the energy storage unit is increased by a preset ratio (e.g., the energy storage weight increases by 0.15 for every level increase); when the energy storage regulation safety margin factor decreases (e.g., the SOC drops to 25%, causing the factor to = 0.5), the weight of the energy storage unit is reduced linearly (e.g., the energy storage weight decreases by 0.05 for every 0.1 decrease in the factor); the weight of the photovoltaic unit is adjusted synchronously in the opposite direction to ensure that the total weight of the two remains constant.

[0043] Step S323: Apply dynamic smoothing constraints to the allocated power adjustment weights to ensure that the weight ratio of photovoltaic units and energy storage units changes continuously with the coupling result and that the total weight remains constant.

[0044] Apply first-order inertial filtering or ramp rate constraints (such as limiting the weight change rate to within ±0.1 per second) to the dynamically allocated power regulation weights. Force the weight ratio of photovoltaic and energy storage to change continuously and smoothly with the grid / energy storage status, eliminate the power command step shock caused by weight jumps, and strictly maintain the sum of photovoltaic weight and energy storage weight constant at a preset total value (such as 1.0).

[0045] The grid urgency level is quantified by the comprehensive level of grid support demand, and the energy storage safety margin factor dynamically reflects the energy storage regulation capability. The two are coupled to achieve adaptive weight allocation. When the grid fails, the weight of energy storage is prioritized to ensure rapid support (e.g., the weight of energy storage increases to 0.8 when the frequency is abnormal). When the energy storage is in a critical safety state, the weight is automatically reduced to prevent overcharging / over-discharging (e.g., the weight of energy storage drops to 0.3 when SOC < 25%). The weight smoothing constraint avoids power mutations, forming a dynamic balance mechanism that takes into account both grid response speed and energy storage life safety.

[0046] Furthermore, in step S400, at the grid-connected converter control layer, adjusting the DC bus voltage based on the total active / reactive power target value to achieve grid support function includes: step S410, calculating the DC bus voltage reference value in real time based on the total active power target value and the voltage control requirements in the grid dispatching instruction, and superimposing the compensation component of the common coupling point voltage deviation.

[0047] Based on the total active power target value, the DC bus voltage reference value is calculated in real time according to the preset power-voltage transfer function, and the real-time feedforward compensation component of the voltage deviation at the point of common coupling is superimposed (such as raising the DC reference voltage by 2% when the voltage drops by 10%), so that the DC side voltage actively responds to grid voltage fluctuations and provides an adaptive voltage regulation reference for the grid-connected converter.

[0048] Step S420: Input the deviation between the DC bus voltage reference value and the measured DC bus voltage into the outer loop voltage controller, output the active current reference value of the grid-connected converter, and at the same time convert the total reactive power target value into the reactive current reference value.

[0049] The deviation between the DC bus voltage reference value and the DC voltage measured by the high-precision sensor is input into the proportional-integral type outer loop voltage controller, which outputs the active current reference value of the grid-connected converter. At the same time, the total reactive power target value is linearly converted into the reactive current reference value based on the grid rated voltage base value, forming the command basis for dual current closed-loop control.

[0050] Step S430: Dynamically adjust the reactive current reference value according to the voltage over-limit level of the point of common coupling. When the grid voltage drops, prioritize increasing the reactive power output and simultaneously limit the active current reference value to meet the low voltage ride-through requirements.

[0051] The reactive current reference value is dynamically adjusted according to the voltage over-limit level of the point of common coupling (e.g., a voltage drop to 0.8 pu is a Level III over-limit). The greater the voltage drop depth, the higher the increase ratio (e.g., the reactive current increases to 1.2 times when the voltage drops by 20%), prioritizing the reactive power support needs of the power grid. The active current reference value is simultaneously limited to the instantaneous current withstand limit of the grid-connected converter (e.g., 1.1 times the rated current) to meet the low voltage ride-through specifications, and the energy storage unit is triggered in reverse to absorb the power surplus based on the active power limiting result.

[0052] In step S440, based on the active current reference value and the reactive current reference value, a pulse width modulation signal is generated through the current inner loop tracking control to drive the grid-connected converter to inject the target power into the grid while maintaining the DC bus voltage stability.

[0053] A current inner-loop decoupling controller in a rotating coordinate system (d-axis tracks active current reference value, q-axis tracks reactive current reference value) is used to suppress harmonic oscillations caused by grid impedance changes by superimposing virtual impedance compensation terms. Based on the voltage command of the decoupling output and the DC bus ripple feedforward compensation, an anti-disturbance pulse width modulation signal is generated to drive the grid-connected converter to stably inject the target power under grid disturbances, while maintaining the DC bus voltage fluctuation rate within ±1% of the rated value.

[0054] By establishing an active support foundation through DC voltage feedforward compensation and dual current reference generation, the voltage over-limit dynamic adjustment strategy realizes reactive power priority output and active power safety current limiting during low voltage ride-through. Current inner loop decoupling control and virtual impedance compensation ensure stable grid-connected power transmission and constant DC voltage, forming a rapid voltage support capability and fault ride-through reliability adapted to grid fault conditions.

[0055] Furthermore, step S430, which dynamically adjusts the reactive current reference value according to the voltage over-limit level of the point of common coupling, prioritizes increasing reactive power output when the grid voltage drops, and simultaneously limits the active current reference value to meet the low voltage ride-through requirements, includes: step S431, mapping the voltage over-limit level of the point of common coupling to a preset reactive power support strength range, generating a dynamic reactive power compensation coefficient, the greater the voltage drop depth, the higher the reactive power compensation coefficient.

[0056] The voltage over-limit level of the point of common coupling is mapped to a preset reactive power support intensity range (e.g., a 10% voltage drop corresponds to a compensation coefficient of 1.2, and a 30% voltage drop corresponds to a coefficient of 1.8), generating a dynamic reactive power compensation coefficient. This coefficient increases monotonically with the depth of voltage drop, quantifying the urgency of reactive power support during grid faults.

[0057] Step S432: Multiply the total reactive power target value by the dynamic reactive power compensation coefficient to generate an enhanced reactive current reference value, and the enhanced reactive current reference value shall not exceed the maximum allowable output current of the grid-connected converter.

[0058] The total reactive power target value is multiplied by the dynamic reactive power compensation coefficient to generate an enhanced reactive current reference value (e.g., the original target 100kVar × coefficient 1.5 → 150kVar). The enhanced reactive current reference value is then rigidly limited by the maximum allowable output current of the grid-connected converter (e.g., 120% of the rated current) to ensure that the enhanced reactive current reference value does not exceed the equipment's safety tolerance.

[0059] Step S433: Based on the enhanced reactive current reference value and the maximum allowable output current of the grid-connected converter, the active current limit value is calculated in real time, so that the active current reference value is constrained to the range of the limit value.

[0060] Based on the enhanced reactive current reference value and the maximum allowable output current of the converter, the active current limit value is calculated in real time (formula: active current limit value = √(maximum allowable current² - enhanced reactive current²)). The active current reference value is forcibly constrained to this limit range to prevent the converter from triggering protection due to the total current exceeding the limit under reactive power generation conditions.

[0061] Step S434: Based on the limiting result of the active current reference value, the total active power target value is reversed, triggering the energy storage unit to prioritize the absorption of the photovoltaic power surplus caused by the active power limiting.

[0062] The total active power target value is reversed based on the limiting result of the active current reference value (e.g., the original target of 500kW is reduced to 400kW due to the limiting). The power surplus (100kW) caused by the active power limitation is triggered by the command redistribution to the energy storage unit for priority consumption, so as to avoid the waste of photovoltaic power or DC bus overvoltage.

[0063] The reactive power support strength during faults is enhanced by the adaptive dynamic reactive power compensation coefficient (S431) based on voltage drop depth, and the rigid limiting of enhanced reactive current (S432) ensures equipment safety. Real-time active current limiting calculation (S433) ensures that the converter does not operate beyond capacity when reactive power is prioritized for output, and active power correction triggers energy storage to absorb power surplus (S434), forming a collaborative protection mechanism of "maximum reactive power support - active power safety constraint - dynamic adjustment of energy storage" during low voltage ride-through.

[0064] Furthermore, in step S440, based on the active current reference value and the reactive current reference value, a pulse width modulation signal is generated through the current inner loop tracking control to drive the grid-connected converter to inject the target power into the grid while maintaining the DC bus voltage stability. This includes step S441, which adjusts the proportional gain and integral time constant of the current inner loop controller in real time based on the harmonic distortion rate of the point of common coupling voltage and the grid impedance change rate.

[0065] Based on real-time monitoring of the harmonic distortion rate of the point of common coupling voltage (e.g., when THD>5%, it is determined that the harmonic pollution is serious) and the rate of change of grid impedance (e.g., when the impedance change exceeds 10%), the proportional gain of the current inner loop controller is dynamically adjusted (the proportional gain is reduced to suppress oscillation when the harmonic distortion rate is high) and the integral time constant is shortened (the integral time is shortened to improve the response speed when the impedance change rate is large), so that the controller parameters adapt to changes in the grid operating state.

[0066] In step S442, a virtual impedance compensation term is superimposed in the inner current loop control. The amplitude of the virtual impedance compensation term is dynamically adjusted according to the direction of the grid frequency deviation in order to suppress the harmonic oscillation of the grid-connected current.

[0067] A virtual impedance compensation term is superimposed in the inner current control loop (its amplitude is dynamically adjusted according to the direction of the grid frequency deviation: inductive virtual impedance is added when the frequency deviation is positive, and capacitive virtual impedance is added when the deviation is negative). The phase compensation mechanism suppresses low-order harmonics (such as the 5th / 7th) and high-frequency oscillation components in the grid-connected current, thereby improving the grid-connected power quality.

[0068] Step S443: A decoupled control structure in a rotating coordinate system is adopted to independently track the active current reference value and the reactive current reference value, wherein the decoupling term is dynamically corrected according to the grid voltage phase.

[0069] A decoupled control structure with a rotating coordinate system (dq axis) is adopted. The d-axis independently tracks the active current reference value to achieve accurate power transmission, and the q-axis independently tracks the reactive current reference value to achieve voltage support. The decoupling term (cross-coupling term) is dynamically corrected based on the grid voltage phase obtained in real time by the phase-locked loop to eliminate mutual interference between the dq axis current controls.

[0070] Step S444: The voltage command output by the decoupling control is superimposed with the DC bus voltage ripple compensation amount, and an anti-disturbance pulse width modulation signal is generated by space vector modulation to drive the grid-connected converter to stably output the target power under grid disturbances.

[0071] The dq-axis voltage command output by the decoupling control is superimposed with the real-time detection compensation amount of DC bus voltage ripple (to offset the influence of second harmonic ripple). An anti-disturbance drive signal is generated through a space vector pulse width modulation algorithm to drive the grid-connected converter to stably output the target power under the conditions of grid background harmonics or impedance sudden change, while maintaining the DC bus voltage fluctuation rate within ±1% of the rated value.

[0072] By using harmonic / impedance adaptive inner loop parameter tuning and virtual impedance dynamic compensation to suppress grid-connected current oscillation, rotating coordinate system decoupling control achieves independent and accurate tracking of active and reactive power, and superimposed DC ripple feedforward compensation enhances anti-disturbance capability, forming a millisecond-level current tracking (delay <5ms) and DC voltage stabilization control closed loop that adapts to complex power grid environments.

[0073] Further, step S500, in which the photovoltaic unit DC / DC converter tracks the commanded power of the photovoltaic unit and the bidirectional DC / DC converter of the energy storage unit tracks the corrected commanded power of the energy storage unit, includes: step S510, dynamically adjusting the search boundary of the maximum power point tracking algorithm based on the commanded power of the photovoltaic unit and the maximum power that the photovoltaic unit can generate, so that the photovoltaic DC / DC converter prioritizes tracking the commanded power and switches to maximum power point operation when the commanded power exceeds the range that can be generated.

[0074] The voltage / current search boundary of the maximum power point tracking algorithm is dynamically adjusted based on the photovoltaic unit's commanded power and maximum achievable power (e.g., when the commanded power is 80kW, the operating point is forced to shift to the curve position corresponding to 80kW), so that the photovoltaic DC / DC converter prioritizes tracking the commanded power. When the commanded power exceeds the maximum achievable power range under the current illumination conditions (e.g., the command is 100kW but the actual maximum is only 90kW), it automatically switches to the traditional MPPT mode to operate at the actual maximum power point, maximizing the utilization of available light resources and reducing curtailment.

[0075] Step S520: Determine the charging and discharging mode based on the corrected energy storage unit command power symbol. In the charging mode, dynamically constrain the charging current based on the upper limit of the state of charge and temperature parameters. In the discharging mode, dynamically constrain the discharging power based on the upper limit of the state of charge and aging factor.

[0076] The operating mode is determined based on the sign of the modified energy storage unit command power (positive value for charging, negative value for discharging): In charging mode, the maximum charging current is dynamically constrained based on the upper limit threshold of state of charge (e.g., triggered when SOC>95%) and battery temperature parameters (current decreases by 5% for every 10°C increase in temperature); in discharging mode, the maximum discharging power is dynamically constrained based on the lower limit threshold of state of charge (e.g., triggered when SOC<15%) and battery aging factor (power decreases by 2% for every 100 cycles), ensuring that the energy storage unit operates within safe boundaries.

[0077] Step S530: Configure adaptive hysteresis widths for the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter respectively. The adaptive hysteresis widths are adjusted in real time according to the DC bus voltage fluctuation rate and the command power change rate to achieve a dynamic balance between switching frequency and power tracking accuracy.

[0078] Adaptive hysteresis width control (threshold bandwidth of hysteresis comparator) is configured for both photovoltaic DC / DC converters and energy storage bidirectional DC / DC converters: the hysteresis width is adjusted in real time based on the DC bus voltage fluctuation rate (increase the hysteresis width to reduce the switching frequency when the fluctuation rate is >2%) and the command power change rate (decrease the hysteresis width to improve the tracking accuracy when the change rate is >10kW / s), so as to achieve a dynamic balance between switching losses and power tracking errors.

[0079] Step S540: The output signal of the dynamic hysteresis control is superimposed with the DC bus voltage ripple feedforward compensation to generate an anti-disturbance pulse drive signal, which drives the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to track the target power in milliseconds under grid disturbances, while suppressing switching transient impacts.

[0080] The output switching signal of dynamic hysteresis control is superimposed with the real-time feedforward compensation of DC bus voltage ripple (to offset second harmonic ripple interference) to generate an anti-disturbance pulse drive signal; this drives the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to track the target power in milliseconds (delay <5ms) under grid voltage fluctuations or load abrupt changes, while suppressing current surges and electromagnetic interference caused by power device switching transients.

[0081] By dynamically adjusting the boundary of photovoltaic MPPT, command power priority tracking and automatic switching over limits are achieved. Energy storage multi-parameter constraint charging and discharging management ensures battery safety. Adaptive hysteresis control balances switching losses and tracking accuracy. Superimposed ripple feedforward compensation achieves disturbance rejection drive, forming a high-precision (error <2%), high-speed (response <5ms) and low-loss power tracking closed loop at the local converter layer.

[0082] Furthermore, in step S530, the adaptive hysteresis width is configured for the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter, respectively, including: step S531, real-time acquisition of DC bus voltage fluctuation rate and command power change rate, and simultaneously acquisition of the current switching frequency and power tracking error of the photovoltaic unit / energy storage unit.

[0083] Real-time acquisition of DC bus voltage fluctuation rate (voltage change amplitude per unit time) and command power change rate (power command change per unit time), and synchronous acquisition of the current actual switching frequency and power tracking error (instantaneous deviation between measured power and command power) of photovoltaic unit DC / DC converter and energy storage bidirectional DC / DC converter.

[0084] Step S532: Map the DC bus voltage fluctuation rate to a preset hysteresis width anti-disturbance range, map the command power change rate to a preset hysteresis width response range, and generate an initial hysteresis width reference value based on the coupling result of the two ranges.

[0085] The DC bus voltage fluctuation rate is mapped to a preset hysteresis width immunity range (e.g., when the fluctuation rate is >2%, it corresponds to immunity level III), and the command power change rate is mapped to the hysteresis width response range (e.g., when the change rate is >10kW / s, it corresponds to response level II). Based on the coupling result of the two ranges (e.g., the superposition of immunity level III and response level II), an initial hysteresis width reference value is generated (e.g., when the sum of levels is 5, the reference value is 0.05V).

[0086] Step S533: Based on the ratio of the current switching frequency to the preset maximum allowable switching frequency and the ratio of the power tracking error to the preset error threshold, the initial hysteresis width reference value is adjusted in both directions. When the switching frequency ratio increases, the hysteresis width is increased to reduce losses. When the tracking error ratio increases, the hysteresis width is decreased to improve accuracy.

[0087] Based on the ratio of the current switching frequency to the preset maximum allowable switching frequency (e.g., actual 20kHz / maximum 25kHz=0.8) and the ratio of the power tracking error to the preset error threshold (e.g., error 3kW / threshold 5kW=0.6), the initial hysteresis width reference value is adjusted in two directions: when the switching frequency ratio increases (e.g., >0.9), the hysteresis width is increased (e.g., +0.01V) to reduce switching losses; when the tracking error ratio increases (e.g., >0.8), the hysteresis width is decreased (e.g., -0.005V) to improve tracking accuracy.

[0088] Step S534: Input the corrected hysteresis width reference value into the hysteresis comparators of the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter respectively, and drive the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to achieve dynamic power point tracking.

[0089] The bidirectional corrected hysteresis width reference value is input into the hysteresis current comparator of the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter respectively, generating a switching drive signal that dynamically adjusts with grid disturbances and command changes, driving the two converters to achieve dynamic balance between switching losses and power tracking accuracy.

[0090] An initial hysteresis reference is generated by mapping voltage fluctuations and power changes. Combined with bidirectional elastic correction of switching frequency ratio and error ratio, the hysteresis width is optimized in real time to balance switching losses and tracking accuracy (the hysteresis is widened to reduce losses at high switching frequencies and narrowed to improve accuracy at high tracking errors), ultimately driving the local converter to achieve dynamic and stable power point tracking.

[0091] Accordingly, referring to Figure 2, a second aspect of the present invention provides a grid-friendly photovoltaic-storage-DC integrated grid-connected control device. The device is characterized by being controlled based on the aforementioned grid-friendly photovoltaic-storage-DC integrated grid-connected control method. The photovoltaic unit is connected to the DC bus via a DC / DC converter, and the energy storage unit is connected via a bidirectional DC / DC converter, forming an integrated power aggregation node on the DC side. The grid-connected control device includes: a data acquisition module 1, used to collect in real-time grid dispatch instructions, point-of-compatibility voltage / frequency deviation, maximum power output of the photovoltaic unit, state of charge of the energy storage unit, and power limits; and a data calculation module 2, used to calculate the amount of power that the grid-connected converter needs to inject into the grid based on the grid dispatch instructions and the point-of-compatibility voltage / frequency deviation. The system comprises: a total active / reactive power target value; a coefficient adjustment module 3, which generates dynamic adjustment coefficients for photovoltaic power and energy storage power in real time based on grid frequency deviation, voltage over-limit level, and energy storage unit charge state, and decomposes the total active power target value into photovoltaic unit command power and energy storage unit command power; a first control module 4, which adjusts the DC bus voltage at the grid-connected converter control layer based on the total active / reactive power target value to achieve grid support function; and a second control module 5, which tracks the photovoltaic unit command power through the photovoltaic unit DC / DC converter and tracks the corrected energy storage unit command power through the bidirectional DC / DC converter of the energy storage unit at the photovoltaic unit control layer and the energy storage unit control layer, achieving millisecond-level power response.

[0092] 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 grid-friendly photovoltaic-storage-DC integrated grid-connected control method.

[0093] 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 grid-friendly photovoltaic-storage-DC integrated grid-connected control method.

[0094] This invention aims to protect a grid-friendly photovoltaic-storage DC integrated grid-connected control method and device, which has the following effects: 1. Through a dynamic coupling mechanism of grid state and energy storage state, the dynamic adjustment coefficients of photovoltaic and energy storage are generated in real time by integrating the grid frequency deviation amplitude, voltage over-limit level and energy storage SOC safety boundary, breaking through the limitations of traditional static allocation strategies; the grid support demand comprehensive level is used to quantify the grid urgency, and the energy storage adjustment safety margin factor is combined to ensure energy storage safety. The dynamic coupling of the two realizes the adaptive allocation of power adjustment weight: when the grid frequency drops sharply or the voltage depth exceeds the limit, the power weight of energy storage is automatically increased to quickly respond to the frequency regulation demand, while the weight of energy storage is reduced when the energy storage SOC is close to the limit to avoid overcharging / over-discharging; dynamic smoothing constraints ensure that the power allocation is continuous and shock-free, solving the power oscillation problem caused by weight jumps in traditional schemes; finally, under grid disturbances, the photovoltaic-storage system can optimize the power allocation ratio in seconds, taking into account grid support and energy storage life, and the system adjustment potential utilization rate is improved by more than 30%; 2. Based on the grid-connected converter's active support strategy, the system's low-voltage ride-through performance is improved through DC bus voltage adaptive adjustment and reactive power priority output mechanism. Specifically: the DC bus voltage reference value is superimposed with PCC voltage deviation compensation, enabling the DC side to actively respond to grid voltage fluctuations; the dynamic reactive power compensation coefficient increases reactive power output in real time according to the voltage drop depth (e.g., prioritizing reactive power generation when the voltage drops to 0.5 pu), while limiting active current to prevent converter overcurrent; virtual impedance compensation and harmonic adaptive control work together to suppress grid current oscillations, ensuring stable operation during faults; ensuring that when the grid voltage drops to 0.5 pu, the reactive power support response time is <20ms, active power recovers smoothly, 100% meeting the latest grid connection standards for low-voltage ride-through, and avoiding unplanned grid disconnection; 3. Through local converter adaptive hysteresis control and power-voltage coordinated disturbance rejection design, high-speed and precise response of the photovoltaic-storage unit is achieved: the photovoltaic DC / DC dynamically adjusts the MPPT boundary, prioritizes commanded power tracking, and seamlessly switches to MPPT mode when the limit is exceeded, reducing curtailment; the energy storage charging and discharging integrates SOC, temperature, and aging factors to dynamically constrain current / power, extending battery life; the hysteresis width elastic correction algorithm balances switching frequency and tracking accuracy in real time according to the bus voltage fluctuation rate and command change rate, reducing switching losses by 15%; and ripple feedforward compensation is superimposed to offset the impact of grid disturbances. Ultimately, under scenarios of dispatch command step or sudden change in illumination, the system power tracking error is <2%, DC bus voltage fluctuation is controlled within ±1%, and power tracking delay is <5ms, significantly improving power quality.

[0095] 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.

[0096] 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, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0097] 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 that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0098] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0099] 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 grid-friendly photovoltaic-storage-DC integrated grid-connected control method, characterized in that, The photovoltaic (PV) unit is connected to the DC bus via a DC / DC converter, and the energy storage unit is connected via a bidirectional DC / DC converter, forming an integrated power aggregation node on the DC side. The grid-connected control method includes the following steps: real-time acquisition of grid dispatch commands, point-of-common coupling (POCC) voltage / frequency deviation, maximum power output of the PV unit, and state of charge and power limits of the energy storage unit; calculation of the total active / reactive power target value to be injected into the grid by the grid-connected converter based on the grid dispatch commands and POCC voltage / frequency deviation; generation of PV power dynamic adjustment coefficients and energy storage power dynamic adjustment coefficients in real time according to the grid frequency deviation amplitude, voltage over-limit level, and energy storage unit state of charge, and decomposition of the total active power target value into PV unit command power and energy storage unit command power; adjustment of the DC bus voltage based on the total active / reactive power target value at the grid-connected converter control layer to achieve grid support function; and tracking of PV unit command power by the PV unit DC / DC converter and the corrected energy storage unit command power by the bidirectional DC / DC converter, achieving millisecond-level power response at the PV unit control layer and energy storage unit control layer.

2. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to claim 1, characterized in that, The process of generating dynamic adjustment coefficients for photovoltaic power and energy storage power in real time based on grid frequency deviation amplitude, voltage over-limit level, and energy storage unit state of charge includes: mapping grid frequency deviation amplitude to a preset frequency support demand range, mapping voltage over-limit level to a preset voltage support demand range, and mapping energy storage unit state of charge to a preset safe operating range for state of charge; assigning real-time power adjustment weights to photovoltaic units and energy storage units based on the coupling result of the frequency support demand range, voltage support demand range, and safe operating range for state of charge; normalizing the power adjustment weights of photovoltaic units to generate dynamic adjustment coefficients for photovoltaic power; and normalizing the power adjustment weights of energy storage units to generate dynamic adjustment coefficients for energy storage power, ensuring that the sum of the two coefficients is a constant value and dynamically changes with the grid / energy storage state.

3. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to claim 2, characterized in that, The method of allocating real-time power regulation weights to photovoltaic (PV) units and energy storage units based on the coupling results of the frequency support demand interval, voltage support demand interval, and state-of-charge (SOC) safe operation interval includes: determining the comprehensive grid support demand level based on preset level weights of the frequency support demand interval and voltage support demand interval, and generating an energy storage regulation safety margin factor according to the boundary of the SOC safe operation interval; dynamically coupling the comprehensive grid support demand level and the energy storage regulation safety margin factor, and allocating power regulation weights to PV units and energy storage units in real time according to the coupling results; increasing the power regulation weight of energy storage units when the comprehensive grid support demand level increases, and decreasing the power regulation weight of energy storage units when the energy storage regulation safety margin factor decreases; and applying dynamic smoothing constraints to the allocated power regulation weights to ensure that the weight ratio of PV units and energy storage units changes continuously with the coupling results and that the total weight remains constant.

4. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to claim 1, characterized in that, The process of adjusting the DC bus voltage based on the total active / reactive power target value to achieve grid support function in the grid-connected converter control layer includes: calculating the DC bus voltage reference value in real time based on the total active power target value and the voltage control requirements in the grid dispatching instructions, and superimposing the compensation component of the point of common coupling voltage deviation; inputting the deviation between the DC bus voltage reference value and the measured DC bus voltage into the outer loop voltage controller, outputting the grid-connected converter active current reference value, and simultaneously converting the total reactive power target value into a reactive current reference value; dynamically adjusting the reactive current reference value according to the point of common coupling voltage over-limit level, prioritizing the increase of reactive power output when the grid voltage drops, and simultaneously limiting the active current reference value to meet the low voltage ride-through requirements; and generating a pulse width modulation signal through the current inner loop tracking control based on the active current reference value and the reactive current reference value to drive the grid-connected converter to inject the target power into the grid while maintaining the DC bus voltage stability.

5. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to claim 4, characterized in that, The step of dynamically adjusting the reactive current reference value based on the voltage overshoot level of the point of common coupling (PCC) to prioritize increasing reactive power output during grid voltage dips while simultaneously limiting the active current reference value to meet low-voltage ride-through requirements includes: mapping the PCC voltage overshoot level to a preset reactive power support strength range to generate a dynamic reactive power compensation coefficient, with a higher coefficient for a greater voltage dip; multiplying the total reactive power target value by the dynamic reactive power compensation coefficient to generate an enhanced reactive current reference value, wherein the enhanced reactive current reference value does not exceed the maximum allowable output current of the grid-connected converter; calculating the active current limit value in real time based on the enhanced reactive current reference value and the maximum allowable output current of the grid-connected converter, thus constraining the active current reference value to within the limit value range; and reversing the total active power target value based on the limit result of the active current reference value, triggering the energy storage unit to prioritize absorbing the photovoltaic power surplus caused by the active power limit.

6. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to claim 4, characterized in that, The method, based on active and reactive current reference values, generates a pulse width modulation signal through current inner loop tracking control to drive the grid-connected converter to inject target power into the grid while maintaining DC bus voltage stability. This includes: adjusting the proportional gain and integral time constant of the current inner loop controller in real time based on the harmonic distortion rate of the point of common coupling voltage and the grid impedance change rate; superimposing a virtual impedance compensation term in the current inner loop control, the amplitude of which is dynamically adjusted according to the grid frequency deviation direction to suppress grid current harmonic oscillations; employing a decoupled control structure in a rotating coordinate system to independently track the active and reactive current reference values, wherein the decoupling term is dynamically corrected according to the grid voltage phase; superimposing the voltage command output from the decoupled control with the DC bus voltage ripple compensation amount, and generating an anti-disturbance pulse width modulation signal through space vector modulation to drive the grid-connected converter to stably output the target power under grid disturbances.

7. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to any one of claims 1-6, characterized in that, The process of tracking the commanded power of the photovoltaic unit via a photovoltaic unit DC / DC converter and tracking the corrected commanded power of the energy storage unit via a bidirectional DC / DC converter of the energy storage unit includes: dynamically adjusting the search boundary of the maximum power point tracking algorithm based on the commanded power of the photovoltaic unit and the maximum power that the photovoltaic unit can generate, so that the photovoltaic DC / DC converter prioritizes tracking the commanded power and switches to maximum power point operation when the commanded power exceeds the range that can be generated; determining the charging and discharging mode based on the sign of the corrected commanded power of the energy storage unit, dynamically constraining the charging current based on the upper limit of the state of charge and temperature parameters in the charging mode, and dynamically constraining the charging current based on the upper limit of the state of charge and temperature parameters in the discharging mode. The discharge power is dynamically constrained by the state-of-charge limit and aging factor; adaptive hysteresis widths are configured for the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter, respectively. The adaptive hysteresis widths are adjusted in real time according to the DC bus voltage fluctuation rate and the command power change rate to achieve a dynamic balance between switching frequency and power tracking accuracy; the output signal of the dynamic hysteresis control is superimposed with the DC bus voltage ripple feedforward compensation to generate an anti-disturbance pulse drive signal, which drives the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to track the target power in milliseconds under grid disturbances, while suppressing switching transient impacts.

8. The grid-friendly photovoltaic-storage-DC integrated grid-connected control method according to claim 7, characterized in that, The method involves configuring adaptive hysteresis widths for the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter, respectively. This includes: real-time acquisition of the DC bus voltage fluctuation rate and the commanded power change rate, while simultaneously obtaining the current switching frequency and power tracking error of the photovoltaic unit / energy storage unit; mapping the DC bus voltage fluctuation rate to a preset hysteresis width anti-interference range, and mapping the commanded power change rate to a preset hysteresis width response range, generating an initial hysteresis width reference value based on the coupling result of the two ranges; performing bidirectional elastic correction on the initial hysteresis width reference value according to the ratio of the current switching frequency to the preset maximum allowable switching frequency and the ratio of the power tracking error to the preset error threshold, increasing the hysteresis width to reduce losses when the switching frequency ratio increases, and decreasing the hysteresis width to improve accuracy when the tracking error ratio increases; and inputting the corrected hysteresis width reference value into the hysteresis comparators of the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter, respectively, to drive the photovoltaic DC / DC converter and the energy storage bidirectional DC / DC converter to achieve dynamic balanced power tracking.

9. A grid-friendly photovoltaic-storage-DC integrated grid-connected control device, characterized in that, Control is performed based on the grid-friendly photovoltaic-storage-DC integrated grid-connected control method as described in any one of claims 1-8. The photovoltaic unit is connected to the DC bus via a DC / DC converter, and the energy storage unit is connected via a bidirectional DC / DC converter, forming an integrated power aggregation node on the DC side. The grid-connected control device includes: a data acquisition module, used to collect in real time grid dispatch commands, point-of-common coupling voltage / frequency deviation, maximum power output of the photovoltaic unit, state of charge of the energy storage unit, and power limits; a data calculation module, used to calculate the target value of total active / reactive power that the grid-connected converter needs to inject into the grid based on the grid dispatch commands and the point-of-common coupling voltage / frequency deviation; and a coefficient adjustment module, used for... Based on the grid frequency deviation amplitude, voltage over-limit level, and energy storage unit state of charge, the system generates real-time dynamic adjustment coefficients for photovoltaic power and energy storage power, and decomposes the total active power target value into photovoltaic unit command power and energy storage unit command power. A first control module is used at the grid-connected converter control layer to adjust the DC bus voltage based on the total active / reactive power target value to achieve grid support function. A second control module is used at the photovoltaic unit control layer and the energy storage unit control layer to track the photovoltaic unit command power through the photovoltaic unit DC / DC converter, and the energy storage unit bidirectional DC / DC converter tracks the corrected energy storage unit command power, achieving millisecond-level power response.

10. An electronic device, characterized in that, include: At least one processor; The at least one processor is connected to a memory; wherein the memory stores instructions that can be executed 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 grid-friendly photovoltaic-storage-DC integrated grid-connected control method as described in any one of claims 1-8.

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