An ac-dc coupled energy management method for a light storage charging and inspection system

Abstract

The application provides a kind of AC-DC coupling energy management method of light storage charging detection system in the technical field of new energy and smart grid, comprising: energy management system monitors the power P_PV_DC of direct current photovoltaic power generation system, the power P_PV_AC of alternating current photovoltaic power generation system, the power P_L_DC of direct current load, the power P_L_AC of alternating current load and the state of charge SOC of energy storage battery system;Based on P_PV_DC, P_PV_AC, P_L_DC, P_L_AC and SOC, control energy storage converter to convert AC-DC according to the preset control strategy;Control strategy uses direct current photovoltaic power generation system to supply power to direct current load first, uses alternating current photovoltaic power generation system to supply power to alternating current load, and when the photovoltaic power of direct current photovoltaic power generation system or alternating current photovoltaic power generation system does not meet the load demand, priority is given to using energy storage battery system to charge and discharge, and finally power is taken from the grid or discharged to the grid.The application has the advantages of: greatly improving system efficiency, compatibility and economy.

Description

Technical Field

[0001] This invention relates to the field of new energy and smart grid technology, and in particular to an AC / DC coupled energy management method for a photovoltaic-storage-charging-testing system. Background Technology

[0002] With the increasing severity of the global energy crisis and environmental pollution, developing and utilizing renewable energy has become a key approach to addressing these challenges. Photovoltaic power generation, as an important form of clean energy, has been widely applied in enterprise-level scenarios. Simultaneously, the rapid development of energy storage technology and the electric vehicle industry has also driven the widespread deployment of "photovoltaic-storage-charge-test" systems—integrating photovoltaic power generation, energy storage buffering, electric vehicle charging, and battery testing functions—in charging stations. This system aims to achieve efficient and stable energy management and optimized operation by coordinating and controlling the energy flow between photovoltaic power generation units, energy storage batteries, charging piles, and the power grid.

[0003] Currently, photovoltaic energy storage charging and testing systems are mainly designed around DC bus architecture and AC bus architecture. Related existing technologies can be further illustrated by the following patent documents: Regarding DC photovoltaic systems, for example, the invention patent with application number 202010060510.3, entitled "An Energy Coordination Control Method for a Photovoltaic-Storage Charging Station," uses DC photovoltaic modules to directly power DC charging piles via a DC-DC converter. While this approach helps reduce the frequent charging and discharging switching of energy storage batteries, it still has significant limitations: the DC power output from the photovoltaic system suffers significant losses during long-distance transmission, resulting in the system generally only suitable for local consumption scenarios, thus limiting the full realization of the photovoltaic power generation potential. Furthermore, such systems typically have difficulty achieving good compatibility with AC charging piles and AC loads used by the site itself (such as lighting and air conditioning), exhibiting weak scalability.

[0004] In the field of AC photovoltaic systems, for example, the invention patent with application number 202211388536.6, entitled "An AC Coupled Photovoltaic-Storage-Charging System," converts photovoltaic DC power to AC power through a photovoltaic inverter and relies on an energy management system (EMS) for coordinated control. While this architecture avoids the losses associated with long-distance DC power transmission, the introduction of photovoltaic inverters and subsequent multi-stage power conversion stages reduces the overall system conversion efficiency. In actual operation, the related energy loss can reach approximately 20%, affecting the system's operational economy and reliability.

[0005] Currently, most systems still employ a single DC or AC bus architecture, making it difficult to flexibly adapt to the increasingly complex AC / DC mixed load demands in charging stations. For example, while DC systems can efficiently serve DC loads such as DC charging piles, they cannot directly and efficiently support AC loads; while AC systems suffer from overall energy efficiency degradation due to multiple energy conversions. This reflects the shortcomings of existing technologies in station-level coordinated control, failing to achieve optimal energy matching between photovoltaic power generation, energy storage units, and diverse loads.

[0006] Based on the above analysis, the main problems of existing optical storage charging and testing systems can be summarized as follows: (1) Low energy conversion efficiency: Pure AC photovoltaic systems require multiple inversion and conversion processes, resulting in significant power loss; pure DC photovoltaic systems are limited by DC transmission loss, making it difficult to support the efficient access and consumption of large-scale, long-distance photovoltaic power generation.

[0007] (2) Insufficient system compatibility: Systems based on a single bus architecture cannot simultaneously and efficiently serve both DC loads (such as DC charging piles) and AC loads (such as equipment used by the station), resulting in reduced resource utilization and a lack of flexibility in system configuration.

[0008] (3) Limited scalability: With the diversification of photovoltaic module types (such as the promotion and application of AC photovoltaic modules), existing systems are unable to effectively integrate widely distributed and scattered photovoltaic resources, which restricts the overall consumption level of renewable energy.

[0009] (4) Economic efficiency needs to be improved: Due to the relatively simple energy management strategy, the system cannot dynamically optimize the coordination between photovoltaic power generation, energy storage charging and discharging and grid interaction during operation, thereby increasing the overall operating cost of the system.

[0010] Therefore, how to provide an AC / DC coupled energy management method for a photovoltaic energy storage charging and testing system to improve system efficiency, compatibility, and economy has become an urgent technical problem to be solved. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide an AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system, thereby improving system efficiency, compatibility and economy.

[0012] This invention is implemented as follows: A method for AC / DC coupling energy management of a photovoltaic energy storage charging and testing system, comprising the following steps: The energy management system monitors the power generation of the DC photovoltaic power generation system (P_PV_DC), the power generation of the AC photovoltaic power generation system (P_PV_AC), the power of the DC load (P_L_DC), the power of the AC load (P_L_AC), and the state of charge (SOC) of the energy storage battery system. The energy management system controls the power conversion system for energy storage to perform AC-DC conversion based on the P_PV_DC, P_PV_AC, P_L_DC, P_L_AC and SOC according to a preset control strategy, so as to optimize energy distribution; The control strategy preferentially uses the DC photovoltaic power generation system to supply power to the DC load, and uses the AC photovoltaic power generation system to supply power to the AC load, and when the photovoltaic power generation power of the DC photovoltaic power generation system or the AC photovoltaic power generation system cannot meet the load demand, the energy storage battery system is preferentially used for charging and discharging operations, and finally power is drawn from the power grid or discharged to the power grid.

[0013] Further, the control strategy executes a first sub-strategy, a second sub-strategy, a third sub-strategy, a fourth sub-strategy, a fifth sub-strategy and a sixth sub-strategy based on the DC load power deficit, the AC load power deficit, the DC photovoltaic power surplus, the AC photovoltaic power surplus, the difference between the SOC and the threshold SOC_min, and the difference between the SOC and the threshold SOC_max; The calculation formulas for the DC load power deficit, the AC load power deficit, the DC photovoltaic power surplus and the AC photovoltaic power surplus are respectively: P_VA_DC=P_L_DC-P_PV_DC; P_VA_AC=P_L_AC-P_PV_AC; P_SUR_DC=P_PV_DC-P_L_DC; P_SUR_AC=P_PV_AC-P_L_AC; Wherein, P_VA_DC represents the DC load power deficit; P_VA_AC represents the AC load power deficit; P_SUR_DC represents the DC photovoltaic power surplus; P_SUR_AC represents the AC photovoltaic power surplus; SOC_min represents the minimum state of charge of the energy storage battery system; SOC_max represents the maximum state of charge of the energy storage battery system.

[0014] Further, the first sub-strategy is specifically: When P_VA_DC>0 and P_VA_AC>0: If SOC<SOC_min, power is drawn from the power grid, the grid power P_G_EX=P_VA_DC+P_VA_AC, and the power of the energy storage converter P_PCS=P_VA_DC, and the energy storage converter performs the AC-to-DC function; If SOC>SOC_min, proceed to judge: If P_SUR_BMS>P_VA_DC+P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_EX=0; P_SUR_BMS represents the power surplus of the energy storage battery system; P_G_EX represents the grid power; If P_SUR_BMS<P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC-P_SUR_BMS, and P_G_EX=P_PCS+P_VA_AC; If P_VA_DC<P_SUR_BMS<P_VA_DC+P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_BMS-P_VA_DC, and P_G_EX=P_VA_AC-P_PCS.

[0015] Further, the second sub-strategy is specifically as follows: When P_SUR_DC>0 and P_VA_AC>0: If P_SUR_DC<P_VA_AC and SOC≤SOC_max, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC, and draws power from the grid, P_G_EX=P_VA_AC-P_SUR_DC; If P_SUR_DC<P_VA_AC and SOC>SOC_max, further judgment is made: If P_SUR_BMS+P_SUR_DC<P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC+P_SUR_BMS, and P_G_EX=P_VA_AC-P_SUR_DC-P_SUR_BMS, and the energy storage battery system discharges to SOC_min; If P_SUR_BMS+P_SUR_DC≥P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_EX=0, and the discharge power of the energy storage battery system P_BMS_D=P_VA_AC-P_SUR_DC.

[0016] Further, the third sub-strategy is specifically as follows: When P_VA_DC>0 and P_SUR_AC>0: If P_SUR_AC<P_VA_DC and SOC≤SOC_max, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC, and draws power from the grid, P_G_EX=P_VA_DC-P_SUR_AC; If P_SUR_AC<P_VA_DC and SOC>SOC_max, proceed to judge: If P_SUR_BMS+P_SUR_AC<P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC-P_SUR_BMS, and P_G_EX=P_VA_DC-P_SUR_BMS-P_SUR_AC, and the energy storage battery system discharges to SOC_min; If P_SUR_BMS+P_SUR_AC≥P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_SUR_AC, and P_G_EX=0, and the discharge power P_BMS_D of the energy storage battery system is P_VA_DC-P_SUR_AC.

[0017] Further, the fourth sub-strategy is specifically: When P_SUR_DC≥P_VA_AC>0: If SOC≥SOC_max, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC, and discharges to the power grid, with the grid discharge power P_G_IN=P_SUR_DC-P_VA_AC; If SOC<SOC_max, proceed to judge: If P_VA_BMS+P_VA_AC<P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC-P_VA_BMS, and discharges to the power grid, P_G_IN=P_SUR_DC-P_VA_AC-P_VA_BMS, and the energy storage battery system is charged to SOC_max; P_VA_BMS represents the maximum allowable charging power value of the energy storage battery system at the current SOC; If P_VA_BMS+P_VA_AC≥P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_IN=0, and the charging power P_BMS_C of the energy storage battery system is P_SUR_DC-P_VA_AC.

[0018] Further, the fifth sub-strategy is specifically: When P_SUR_AC≥P_VA_DC>0: If SOC≥SOC_max, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC, and discharges to the power grid, with the grid discharge power P_G_IN=P_SUR_AC-P_VA_DC; If SOC<SOC_max, proceed to judge: If P_VA_BMS+P_VA_DC<P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC+P_VA_BMS, and discharges to the power grid, P_G_IN=P_SUR_AC-P_VA_DC-P_VA_BMS, and the energy storage battery system is charged to SOC_max; If P_VA_BMS+P_VA_DC≥P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_SUR_AC, and P_G_IN=0, the charging power P_BMS_C of the energy storage battery system is P_SUR_AC-P_VA_DC.

[0019] Further, the sixth sub-strategy is specifically as follows: When P_SUR_DC>0 and P_SUR_AC>0: If SOC≥SOC_max, discharge to the power grid, the power grid discharge power P_G_IN=P_SUR_DC+P_SUR_AC, and the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC; If SOC<SOC_max, further judgment is made: If P_VA_BMS≤P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC-P_VA_BMS, and discharges to the power grid, P_G_IN=P_PCS+P_SUR_AC; If P_SUR_DC≤P_VA_BMS≤P_SUR_DC+P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_BMS-P_SUR_DC, and discharges to the power grid, P_G_IN=P_SUR_AC-P_PCS; If P_VA_BMS>P_SUR_DC+P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_SUR_AC, and P_G_IN=0.

[0020] Further, the configuration of the DC photovoltaic power generation system and the AC photovoltaic power generation system is allocated based on the load distance: A load distance of 120 meters is configured as a DC photovoltaic power generation system, which is connected to the DC bus through a DC converter; A load distance of more than 120 meters is configured as an AC photovoltaic power generation system, which is connected to the AC bus through a photovoltaic inverter to reduce line loss.

[0021] Furthermore, the control strategy dynamically optimizes the coordination between the photovoltaic power generation of the DC photovoltaic power generation system and the AC photovoltaic power generation system, the charging and discharging of the energy storage battery system and the grid interaction during operation, so as to reduce the overall operating cost and improve the energy conversion efficiency by reducing the number of conversions of the energy storage converter.

[0022] The advantages of this invention are: 1. By constructing an AC / DC coupled system architecture and implementing a dynamically optimized multi-mode control strategy based on real-time monitoring of power generation, load, and battery status data, the system systematically improves efficiency, compatibility, and economy. Specifically, by adopting the principle of "nearby consumption" (DC photovoltaics prioritize supplying DC loads, and AC photovoltaics prioritize supplying AC loads) and optimizing photovoltaic configuration according to load distance, unnecessary AC / DC conversions and long-distance transmission losses are minimized, directly improving system efficiency. Its inherent AC / DC hybrid bus design is naturally compatible with various AC / DC loads and diverse photovoltaic modules, solving the compatibility problem of a single architecture. The refined strategy dynamically optimizes energy flow during operation, always prioritizing the use of photovoltaics and intelligently scheduling energy storage for peak shaving and valley filling, and only interacting with the grid last, thereby significantly reducing overall operating costs and ultimately greatly improving system efficiency, compatibility, and economy.

[0023] 2. The control strategy clearly prioritizes the use of DC photovoltaic power to supply DC loads and AC photovoltaic power to supply AC loads. This "local and homogeneous matching" power supply principle minimizes the AC-DC conversion links. Since power electronic conversion devices (such as inverters and rectifiers) inevitably incur losses during energy conversion, reducing unnecessary conversions directly reduces internal system losses, thereby significantly improving the overall energy utilization efficiency from photovoltaic power generation to load power consumption.

[0024] 3. Through six specific sub-strategies, all possible mismatch scenarios between photovoltaic power generation and load demand are comprehensively covered (such as dual deficit, one surplus and one deficit, dual surplus, etc.). Each sub-strategy comprehensively considers the power surplus and deficit on the DC / AC side, the state of charge (SOC) of the energy storage battery and its safety threshold (SOC_min / SOC_max), and decides the power flow direction and magnitude of the energy storage converter (PCS) and the interaction mode with the grid accordingly. This refined strategy system enables the system to act like an "intelligent brain" and automatically select the optimal energy flow path under complex and variable operating conditions to achieve intelligent scheduling.

[0025] 4. The control strategy establishes an energy consumption order of "photovoltaic priority, energy storage regulation, and grid last." When photovoltaic power is insufficient, energy storage batteries are used first to supplement it; when photovoltaic power is abundant, energy storage batteries are charged first. This principle maximizes the storage and absorption of local renewable energy, reduces the demand for electricity from the public grid, and thus improves the user's energy self-sufficiency. This not only reduces electricity costs (especially when there is a significant peak-valley price difference), but also alleviates the power supply pressure on the grid, which is in line with the development direction of distributed energy systems.

[0026] 5. Configure DC or AC photovoltaic power generation systems based on load distance (120 meters as the boundary). For short-distance loads, using a DC system can avoid inverter losses and long-distance AC transmission losses. For long-distance loads, using mature AC high-voltage transmission is more economical and reliable. This optimized configuration based on electrical characteristics and physical layout during the system design stage reduces the inherent losses in the power transmission process from the source and further improves the economic efficiency of system operation throughout its entire life cycle.

[0027] 6. Through a sophisticated hierarchical decision-making and dynamic optimization mechanism, the AC / DC coupled photovoltaic power generation, energy storage batteries, diverse loads, and the power grid are constructed into a collaborative and organic whole. The control strategy prioritizes the local direct supply of photovoltaic power generation and similar loads, minimizing unnecessary AC / DC conversion losses and thus improving the overall energy efficiency of the system. At the same time, based on real-time power difference and energy storage status, the strategy intelligently schedules the energy storage system for flexible charging and discharging, prioritizing the use of internal resources for balancing in various energy surplus and deficit scenarios, effectively improving energy self-sufficiency and economy. In addition, the system architecture has also been optimized, and the energy flow is dynamically adjusted according to operating data. Ultimately, while ensuring stable system operation, it comprehensively achieves multiple beneficial effects such as reducing operating costs, extending equipment life, and improving energy utilization efficiency. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Figure 1 This is a flowchart of an AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system according to the present invention.

[0030] Figure 2 This is a hardware architecture diagram of the present invention. Detailed Implementation

[0031] The overall concept of the technical solution in this application is as follows: by adopting the principle of "nearby consumption" and optimizing photovoltaic configuration according to load distance, unnecessary AC / DC conversion times and long-distance transmission losses are reduced; its inherent AC / DC hybrid bus design is naturally compatible with various AC / DC loads and diverse photovoltaic modules, solving the compatibility problem of a single architecture; and the refined strategy dynamically optimizes energy flow during operation, always prioritizing the use of photovoltaics and intelligently scheduling energy storage for peak shaving and valley filling, and finally interacting with the grid, significantly reducing the overall operating cost, thereby improving system efficiency, compatibility and economy.

[0032] Please refer to Figures 1 to 2 As shown, a preferred embodiment of the AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system of the present invention includes the following steps: The energy management system monitors the power generation of the DC photovoltaic power generation system (P_PV_DC), the power generation of the AC photovoltaic power generation system (P_PV_AC), the power of the DC load (P_L_DC), the power of the AC load (P_L_AC), and the state of charge (SOC) of the energy storage battery system. The energy management system, based on the P_PV_DC, P_PV_AC, P_L_DC, P_L_AC and SOC, controls the energy storage converter to perform AC-DC conversion according to a preset control strategy in order to optimize energy distribution. The control strategy prioritizes using DC photovoltaic power generation systems to power DC loads and AC photovoltaic power generation systems to power AC loads. When the photovoltaic power generation of either the DC or AC photovoltaic power generation system is insufficient to meet the load demand, the energy storage battery system is prioritized for charging and discharging operations. Finally, power is drawn from the grid or discharged to the grid.

[0033] In a specific application scenario, such as an electric vehicle charging station equipped with DC charging piles (e.g., fast charging piles) and AC charging piles (e.g., slow charging piles), the Energy Management System (EMS) can be deployed on a local server or cloud platform to collect operating parameters such as P_PV_DC, P_PV_AC, P_L_DC, P_L_AC, and SOC in real time at a preset sampling period (e.g., 1 second to 1 minute). The Energy Storage Converter (PCS) is a bidirectional converter device, whose core function is to realize bidirectional energy flow between the AC bus and the DC bus, that is, to perform AC / DC rectification (drawing power from the grid or converting AC photovoltaic surplus to DC) or DC / AC inversion (discharging to the grid or converting DC photovoltaic surplus to AC).

[0034] The control strategy can be programmed into the control logic of the energy management system. The priority order of the strategies embodies the principle of optimal economy of energy utilization: first, maximize the local consumption of photovoltaic power generation to reduce energy conversion links (such as direct supply of electric power of the same type); second, use the energy storage battery for peak shaving and valley filling to smooth the volatility and intermittency of photovoltaic power generation, and reduce electricity cost by utilizing the peak-valley electricity price difference; finally, take the power grid as the backup power source or the absorber of surplus electric energy, so as to ensure the power supply reliability of the system and possibly obtain revenue through electricity sales.

[0035] The control strategy executes the first sub-strategy, the second sub-strategy, the third sub-strategy, the fourth sub-strategy, the fifth sub-strategy and the sixth sub-strategy based on the DC load power deficit, the AC load power deficit, the DC photovoltaic power surplus, the AC photovoltaic power surplus, the difference between SOC and the threshold SOC_min, and the difference between SOC and the threshold SOC_max; The calculation formulas for the DC load power deficit, the AC load power deficit, the DC photovoltaic power surplus and the AC photovoltaic power surplus are respectively as follows: P_VA_DC=P_L_DC-P_PV_DC; P_VA_AC=P_L_AC-P_PV_AC; P_SUR_DC=P_PV_DC-P_L_DC; P_SUR_AC=P_PV_AC-P_L_AC; Wherein, P_VA_DC represents the DC load power deficit; P_VA_AC represents the AC load power deficit; P_SUR_DC represents the DC photovoltaic power surplus; P_SUR_AC represents the AC photovoltaic power surplus; SOC_min represents the minimum state of charge of the energy storage battery system; SOC_max represents the maximum state of charge of the energy storage battery system.

[0036] The first sub-strategy is specifically as follows: When P_VA_DC>0 and P_VA_AC>0: If SOC<SOC_min, power is drawn from the power grid, the power grid power P_G_EX=P_VA_DC+P_VA_AC, and the power of the energy storage converter P_PCS=P_VA_DC, the energy storage converter performs the AC-to-DC function; If SOC>SOC_min, proceed to judge: If P_SUR_BMS>P_VA_DC+P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_EX=0; P_SUR_BMS represents the power surplus of the energy storage battery system; P_G_EX represents the power grid power; If P_SUR_BMS < P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS = P_VA_DC - P_SUR_BMS, and P_G_EX = P_PCS + P_VA_AC; If P_VA_DC < P_SUR_BMS < P_VA_DC + P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS = P_SUR_BMS - P_VA_DC, and P_G_EX = P_VA_AC - P_PCS.

[0037] The second sub-strategy is specifically as follows: When P_SUR_DC > 0 and P_VA_AC > 0: If P_SUR_DC < P_VA_AC and SOC ≤ SOC_max, the energy storage converter performs the DC-to-AC function, P_PCS = P_SUR_DC, and power is drawn from the power grid, P_G_EX = P_VA_AC - P_SUR_DC; If P_SUR_DC < P_VA_AC and SOC > SOC_max, further judgment is made: If P_SUR_BMS + P_SUR_DC < P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS = P_SUR_DC + P_SUR_BMS, and P_G_EX = P_VA_AC - P_SUR_DC - P_SUR_BMS, and the energy storage battery system discharges to SOC_min; If P_SUR_BMS + P_SUR_DC ≥ P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS = P_VA_AC, and P_G_EX = 0, and the discharge power P_BMS_D of the energy storage battery system is P_VA_AC - P_SUR_DC.

[0038] The third sub-strategy is specifically as follows: When P_VA_DC > 0 and P_SUR_AC > 0: If P_SUR_AC < P_VA_DC and SOC ≤ SOC_max, the energy storage converter performs the AC-to-DC function, P_PCS = P_VA_DC, and power is drawn from the power grid, P_G_EX = P_VA_DC - P_SUR_AC; If P_SUR_AC < P_VA_DC and SOC > SOC_max, further judgment is made: If P_SUR_BMS+P_SUR_AC<P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC-P_SUR_BMS, and P_G_EX=P_VA_DC-P_SUR_BMS-P_SUR_AC, and the energy storage battery system discharges to SOC_min; If P_SUR_BMS+P_SUR_AC≥P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_SUR_AC, and P_G_EX=0, and the discharge power P_BMS_D of the energy storage battery system is P_VA_DC-P_SUR_AC.

[0039] The fourth sub-strategy is specifically as follows: When P_SUR_DC≥P_VA_AC>0: If SOC≥SOC_max, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC, and discharges to the power grid, with the grid discharge power P_G_IN=P_SUR_DC-P_VA_AC; If SOC<SOC_max, proceed to judge: If P_VA_BMS+P_VA_AC<P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC-P_VA_BMS, and discharges to the power grid, P_G_IN=P_SUR_DC-P_VA_AC-P_VA_BMS, the energy storage battery system is charged to SOC_max; P_VA_BMS represents the maximum allowable charging power value of the energy storage battery system at the current SOC; If P_VA_BMS+P_VA_AC≥P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_IN=0, and the charging power P_BMS_C of the energy storage battery system is P_SUR_DC-P_VA_AC.

[0040] The fifth sub-strategy is specifically as follows: When P_SUR_AC≥P_VA_DC>0: If SOC≥SOC_max, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC, and discharges to the power grid, with the grid discharge power P_G_IN=P_SUR_AC-P_VA_DC; If SOC<SOC_max, proceed to judge: If P_VA_BMS+P_VA_DC<P_SUR_AC, the energy storage converter performs an AC-to-DC function, P_PCS=P_VA_DC+P_VA_BMS, and discharges to the power grid, where P_G_IN=P_SUR_AC-P_VA_DC-P_VA_BMS, and the energy storage battery system is charged to SOC_max; If P_VA_BMS+P_VA_DC≥P_SUR_AC, the energy storage converter performs an AC-to-DC function, P_PCS=P_SUR_AC, and P_G_IN=0, where the charging power of the energy storage battery system P_BMS_C=P_SUR_AC-P_VA_DC.

[0041] The sixth sub-strategy is specifically as follows: When P_SUR_DC>0 and P_SUR_AC>0: If SOC≥SOC_max, discharge to the power grid, the grid discharge power P_G_IN=P_SUR_DC+P_SUR_AC, and the energy storage converter performs a DC-to-AC function, where P_PCS=P_SUR_DC; If SOC<SOC_max, proceed with the judgment: If P_VA_BMS≤P_SUR_DC, the energy storage converter performs a DC-to-AC function, P_PCS=P_SUR_DC-P_VA_BMS, and discharges to the power grid, where P_G_IN=P_PCS+P_SUR_AC; If P_SUR_DC≤P_VA_BMS≤P_SUR_DC+P_SUR_AC, the energy storage converter performs an AC-to-DC function, P_PCS=P_VA_BMS-P_SUR_DC, and discharges to the power grid, where P_G_IN=P_SUR_AC-P_PCS; If P_VA_BMS>P_SUR_DC+P_SUR_AC, the energy storage converter performs an AC-to-DC function, P_PCS=P_SUR_AC, and P_G_IN=0.

[0042] To further illustrate the dynamic decision-making process of the sub-strategy, a simplified embodiment combined with typical parameters is provided as follows: Assume that at a certain moment, SOC_min is set to 20%, and SOC_max is set to 90%. It is monitored that P_PV_DC=50kW, P_L_DC=30kW, P_PV_AC=40kW, P_L_AC=60kW, and SOC=75%.

[0043] Then the calculation gives: P_SUR_DC=50-30=20kW (surplus), P_VA_AC=60-40=20kW (deficit). This scenario meets the initial condition of the second sub-strategy (P_SUR_DC>0 and P_VA_AC>0).

[0044] Since SOC=75%<SOC_max=90%, and assuming P_SUR_DC (20kW)<P_VA_AC (20kW), the first case of this sub-strategy is executed: the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC=20kW, converting the 20kW surplus DC photovoltaic power into alternating current, while power still needs to be drawn from the grid P_G_EX=P_VA_AC-P_SUR_DC=20-20=0kW. In this example, the DC photovoltaic surplus exactly makes up for the AC load deficit, no power needs to be drawn from the grid, which reflects the effect of the system's internal energy optimal scheduling.

[0045] The configuration of the DC photovoltaic power generation system and the AC photovoltaic power generation system is allocated based on the load distance: A load with a distance of 120 meters is configured as a DC photovoltaic power generation system, which is connected to the DC bus through a DC converter; A load with a distance of more than 120 meters is configured as an AC photovoltaic power generation system, which is connected to the AC bus through a photovoltaic inverter to reduce line losses.

[0046] With reference to Figure 2 the hardware architecture diagram shown, the system includes a DC photovoltaic power generation system, a DC load (such as a DC charging pile), an energy storage battery system (connected via a bidirectional DC / DC converter), and the DC side of the energy storage converter (PCS) connected through a DC bus. At the same time, it includes an AC photovoltaic power generation system, an AC load (such as an AC charging pile, station daily electrical equipment), a grid interface, and the AC side of the energy storage converter (PCS) connected through an AC bus. The energy management system (EMS) is connected to devices such as the photovoltaic inverter, DC converter, energy storage converter, battery management system (BMS), and smart meter through a communication network (such as CAN bus, Ethernet or wireless communication) to realize data collection and control instruction issuance. This AC-DC hybrid bus architecture provides a physical basis for the energy management method, enabling flexible and efficient energy interaction among DC photovoltaic power generation, AC photovoltaic power generation, energy storage batteries, AC and DC loads, and the power grid.

[0047] When running, the control strategy dynamically optimizes the cooperation relationship between the photovoltaic power generation of the DC photovoltaic power generation system and the AC photovoltaic power generation system, the charging and discharging of the energy storage battery system, and the grid interaction, so as to reduce the comprehensive operation cost and improve the energy conversion efficiency by reducing the conversion times of the energy storage converter.

[0048] The operation of the control strategy can be further optimized based on real-time electricity price signals. For example, during peak power hours, even if the State of Charge (SOC) is higher than SOC_min, the power drawn from the grid can be appropriately reduced, and energy storage can be used for discharge first. During off-peak hours, energy storage can be charged from the grid first for use during peak hours. This economic optimization further reduces the operating cost of the system throughout its entire life cycle. In summary, the advantages of this invention are as follows: 1. By constructing an AC / DC coupled system architecture and implementing a dynamically optimized multi-mode control strategy based on real-time monitoring of power generation, load, and battery status data, the system systematically improves efficiency, compatibility, and economy. Specifically, by adopting the principle of "nearby consumption" (DC photovoltaics prioritize supplying DC loads, and AC photovoltaics prioritize supplying AC loads) and optimizing photovoltaic configuration according to load distance, unnecessary AC / DC conversions and long-distance transmission losses are minimized, directly improving system efficiency. Its inherent AC / DC hybrid bus design is naturally compatible with various AC / DC loads and diverse photovoltaic modules, solving the compatibility problem of a single architecture. The refined strategy dynamically optimizes energy flow during operation, always prioritizing the use of photovoltaics and intelligently scheduling energy storage for peak shaving and valley filling, and only interacting with the grid last, thereby significantly reducing overall operating costs and ultimately greatly improving system efficiency, compatibility, and economy.

[0049] 2. The control strategy clearly prioritizes the use of DC photovoltaic power to supply DC loads and AC photovoltaic power to supply AC loads. This "local and homogeneous matching" power supply principle minimizes the AC-DC conversion links. Since power electronic conversion devices (such as inverters and rectifiers) inevitably incur losses during energy conversion, reducing unnecessary conversions directly reduces internal system losses, thereby significantly improving the overall energy utilization efficiency from photovoltaic power generation to load power consumption.

[0050] 3. Through six specific sub-strategies, all possible mismatch scenarios between photovoltaic power generation and load demand are comprehensively covered (such as dual deficit, one surplus and one deficit, dual surplus, etc.). Each sub-strategy comprehensively considers the power surplus and deficit on the DC / AC side, the state of charge (SOC) of the energy storage battery and its safety threshold (SOC_min / SOC_max), and decides the power flow direction and magnitude of the energy storage converter (PCS) and the interaction mode with the grid accordingly. This refined strategy system enables the system to act like an "intelligent brain" and automatically select the optimal energy flow path under complex and variable operating conditions to achieve intelligent scheduling.

[0051] 4. The control strategy establishes an energy consumption order of "photovoltaic priority, energy storage regulation, and grid last." When photovoltaic power is insufficient, energy storage batteries are used first to supplement it; when photovoltaic power is abundant, energy storage batteries are charged first. This principle maximizes the storage and absorption of local renewable energy, reduces the demand for electricity from the public grid, and thus improves the user's energy self-sufficiency. This not only reduces electricity costs (especially when there is a significant peak-valley price difference), but also alleviates the power supply pressure on the grid, which is in line with the development direction of distributed energy systems.

[0052] 5. Configure DC or AC photovoltaic power generation systems based on load distance (120 meters as the boundary). For short-distance loads, using a DC system can avoid inverter losses and long-distance AC transmission losses. For long-distance loads, using mature AC high-voltage transmission is more economical and reliable. This optimized configuration based on electrical characteristics and physical layout during the system design stage reduces the inherent losses in the power transmission process from the source and further improves the economic efficiency of system operation throughout its entire life cycle.

[0053] 6. Through a sophisticated hierarchical decision-making and dynamic optimization mechanism, the AC / DC coupled photovoltaic power generation, energy storage batteries, diverse loads, and the power grid are constructed into a collaborative and organic whole. The control strategy prioritizes the local direct supply of photovoltaic power generation and similar loads, minimizing unnecessary AC / DC conversion losses and thus improving the overall energy efficiency of the system. At the same time, based on real-time power difference and energy storage status, the strategy intelligently schedules the energy storage system for flexible charging and discharging, prioritizing the use of internal resources for balancing in various energy surplus and deficit scenarios, effectively improving energy self-sufficiency and economy. In addition, the system architecture has also been optimized, and the energy flow is dynamically adjusted according to operating data. Ultimately, while ensuring stable system operation, it comprehensively achieves multiple beneficial effects such as reducing operating costs, extending equipment life, and improving energy utilization efficiency.

[0054] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for AC / DC coupled energy management of a photovoltaic energy storage charging and testing system, characterized in that: comprising the following steps: an energy management system monitors the generated power P_PV_DC of a DC photovoltaic power generation system, the generated power P_PV_AC of an AC photovoltaic power generation system, the power P_L_DC of a DC load, the power P_L_AC of an AC load, and the state of charge SOC of an energy storage battery system; the energy management system controls an energy storage converter to perform AC-DC conversion according to a preset control strategy based on the P_PV_DC, P_PV_AC, P_L_DC, P_L_AC and the SOC, so as to optimize energy distribution; the control strategy prioritizes using the DC photovoltaic power generation system to supply power to the DC load, and using the AC photovoltaic power generation system to supply power to the AC load, and when the photovoltaic power generation power of the DC photovoltaic power generation system or the AC photovoltaic power generation system cannot meet the load demand, prioritizes using the energy storage battery system to perform charging and discharging operations, and finally takes power from the power grid or discharges power to the power grid.

2. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 1, characterized in that: the control strategy executes a first sub-strategy, a second sub-strategy, a third sub-strategy, a fourth sub-strategy, a fifth sub-strategy and a sixth sub-strategy based on a DC load power deficit, an AC load power deficit, a DC photovoltaic power surplus, an AC photovoltaic power surplus, the difference between the SOC and the threshold SOC_min, and the difference between the SOC and the threshold SOC_max; the calculation formulas for the DC load power deficit, the AC load power deficit, the DC photovoltaic power surplus and the AC photovoltaic power surplus are respectively as follows: P_VA_DC=P_L_DC-P_PV_DC; P_VA_AC=P_L_AC-P_PV_AC; P_SUR_DC=P_PV_DC-P_L_DC; P_SUR_AC=P_PV_AC-P_L_AC; wherein P_VA_DC represents the DC load power deficit; P_VA_AC represents the AC load power deficit; P_SUR_DC represents the DC photovoltaic power surplus; P_SUR_AC represents the AC photovoltaic power surplus; SOC_min represents the minimum state of charge of the energy storage battery system; SOC_max represents the maximum state of charge of the energy storage battery system.

3. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 2, characterized in that: The first sub-strategy is specifically as follows: When P_VA_DC>0 and P_VA_AC>0: If SOC<SOC_min, power is taken from the power grid, the power grid power P_G_EX=P_VA_DC+P_VA_AC, and the power P_PCS of the energy storage converter is P_VA_DC, and the energy storage converter performs the AC-to-DC function; If SOC>SOC_min, further judgment is performed: If P_SUR_BMS>P_VA_DC+P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_EX=0; P_SUR_BMS represents the power surplus of the energy storage battery system; P_G_EX represents the power grid power; If P_SUR_BMS<P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC-P_SUR_BMS, and P_G_EX=P_PCS+P_VA_AC; If P_VA_DC<P_SUR_BMS<P_VA_DC+P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_BMS-P_VA_DC, and P_G_EX=P_VA_AC-P_PCS.

4. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 2, characterized in that: The second sub-strategy is specifically as follows: When P_SUR_DC>0 and P_VA_AC>0: If P_SUR_DC<P_VA_AC and SOC≤SOC_max, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC, and power is drawn from the power grid, where P_G_EX=P_VA_AC-P_SUR_DC; If P_SUR_DC<P_VA_AC and SOC>SOC_max, further judgment is made: If P_SUR_BMS+P_SUR_DC<P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC+P_SUR_BMS, and P_G_EX=P_VA_AC-P_SUR_DC-P_SUR_BMS, and the energy storage battery system discharges to SOC_min; If P_SUR_BMS+P_SUR_DC≥P_VA_AC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_EX=0, and the discharge power P_BMS_D of the energy storage battery system is P_VA_AC-P_SUR_DC.

5. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 2, characterized in that: The third sub-strategy is specifically as follows: When P_VA_DC>0 and P_SUR_AC>0: If P_SUR_AC<P_VA_DC and SOC≤SOC_max, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC, and power is drawn from the power grid, where P_G_EX=P_VA_DC-P_SUR_AC; If P_SUR_AC<P_VA_DC and SOC>SOC_max, further judgment is made: If P_SUR_BMS+P_SUR_AC<P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC-P_SUR_BMS, and P_G_EX=P_VA_DC-P_SUR_BMS-P_SUR_AC, and the energy storage battery system discharges to SOC_min; If P_SUR_BMS+P_SUR_AC≥P_VA_DC, the energy storage converter performs the AC-to-DC function, P_PCS=P_SUR_AC, and P_G_EX=0, and the discharge power P_BMS_D of the energy storage battery system is P_VA_DC-P_SUR_AC.

6. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 2, characterized in that: The fourth sub-strategy is specifically as follows: When P_SUR_DC≥P_VA_AC>0: If SOC≥SOC_max, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC, and discharges power to the power grid, where the grid discharge power P_G_IN=P_SUR_DC-P_VA_AC; If SOC<SOC_max, further judgment is made: If P_VA_BMS+P_VA_AC<P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC-P_VA_BMS, and discharges to the power grid, P_G_IN=P_SUR_DC-P_VA_AC-P_VA_BMS, and the energy storage battery system is charged to SOC_max; P_VA_BMS represents the maximum allowable charging power value of the energy storage battery system at the current SOC; If P_VA_BMS+P_VA_AC≥P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_VA_AC, and P_G_IN=0, and the charging power of the energy storage battery system P_BMS_C=P_SUR_DC-P_VA_AC.

7. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 2, characterized in that: The fifth sub-strategy is specifically as follows: When P_SUR_AC≥P_VA_DC>0: If SOC≥SOC_max, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC, and discharges to the power grid, and the grid discharge power P_G_IN=P_SUR_AC-P_VA_DC; If SOC<SOC_max, proceed to judge: If P_VA_BMS+P_VA_DC<P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_DC+P_VA_BMS, and discharges to the power grid, P_G_IN=P_SUR_AC-P_VA_DC-P_VA_BMS, and the energy storage battery system is charged to SOC_max; If P_VA_BMS+P_VA_DC≥P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_SUR_AC, and P_G_IN=0, and the charging power of the energy storage battery system P_BMS_C=P_SUR_AC-P_VA_DC.

8. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 2, characterized in that: The sixth sub-strategy is specifically as follows: When P_SUR_DC>0 and P_SUR_AC>0: If SOC≥SOC_max, discharge to the power grid, the grid discharge power P_G_IN=P_SUR_DC+P_SUR_AC, and the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC; If SOC<SOC_max, proceed to judge: If P_VA_BMS≤P_SUR_DC, the energy storage converter performs the DC-to-AC function, P_PCS=P_SUR_DC-P_VA_BMS, and discharges to the power grid, P_G_IN=P_PCS+P_SUR_AC; If P_SUR_DC≤P_VA_BMS≤P_SUR_DC+P_SUR_AC, the energy storage converter performs the AC-to-DC function, P_PCS=P_VA_BMS-P_SUR_DC, and discharges to the power grid, P_G_IN=P_SUR_AC-P_PCS; If P_VA_BMS > P_SUR_DC + P_SUR_AC, then the energy storage converter performs AC to DC conversion, P_PCS = P_SUR_AC, and P_G_IN = 0.

9. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 1, characterized in that: The configuration of the DC photovoltaic power generation system and the AC photovoltaic power generation system is allocated based on the load distance: The load distance is 120 meters, configured as a DC photovoltaic power generation system, and connected to the DC bus through a DC converter; For loads more than 120 meters away, an AC photovoltaic power generation system is configured, which is connected to the AC bus via a photovoltaic inverter to reduce line losses.

10. The AC / DC coupling energy management method for a photovoltaic energy storage charging and testing system as described in claim 1, characterized in that: The control strategy dynamically optimizes the coordination between the photovoltaic power generation of the DC photovoltaic power generation system and the AC photovoltaic power generation system, the charging and discharging of the energy storage battery system and the grid interaction during operation, so as to reduce the overall operating cost and improve the energy conversion efficiency by reducing the number of conversions of the energy storage converter.

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