Wind-solar hybrid energy storage microgrid system based on ac-dc coupling, control method thereof and related equipment

Abstract

This application discloses a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, its control method, and related equipment, which can be applied to the field of integrated energy and energy storage control technology. This application divides the microgrid system into an AC grid domain and a DC grid domain, and connects the AC and DC grid domains through a bidirectional AC / DC interconnection converter. Wind power generation devices, AC buses, and gravity energy storage devices are installed in the AC grid domain to connect to AC loads, while photovoltaic power generation devices, DC buses, and DC energy storage devices are installed in the DC grid domain to connect to DC loads. This achieves frequency band separation and decoupling of AC / DC control objectives, fundamentally reducing the risk of AC / DC linkage oscillations, effectively reducing temperature rise and capacity decay, and improving operational stability.

Description

Technical Field

[0001] This application relates to the field of integrated energy and energy storage control technology, and in particular to a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, its control method and related equipment. Background Technology

[0002] In related technologies, with the continuous increase in the proportion of clean energy, the distribution terminal is undergoing a structural transformation from "single power receiving" to "multiple entities, local balance, and two-way interaction." Especially in mountainous and hilly areas, although there are abundant wind and solar resources, they are generally constrained by geographical conditions and face physical bottlenecks such as weak grid support, long feeder paths, and limited short-circuit capacity. Against this backdrop, the randomness of new energy output can easily trigger power quality hazards such as frequency fluctuations, voltage flicker, and excessive harmonics; in addition, due to the limitation of transmission capacity, the phenomenon of wind and solar curtailment is also very serious. At the same time, the penetration rate of DC intrinsic loads (such as communication sites, data processing equipment, LED arrays, DC charging piles, etc.) is rapidly increasing, and the traditional all-AC power supply architecture is difficult to meet the demand for efficient energy supply due to multi-level energy efficiency conversion and harmonic superposition.

[0003] Existing microgrid technologies mostly follow a "full AC aggregation + single-point electrochemical energy storage" model. In this model, all power sources and loads are connected via the AC side, relying on lithium battery packs to passively respond to power fluctuations across the entire frequency range (from milliseconds to hours). While this single-dimensional regulation mechanism is advantageous for early deployment, in actual operation, it subjectes batteries to frequent high-frequency pulses and deep charge / discharge stress, leading to severe temperature rise and capacity decay. Under a weak spindle architecture, the AC side frequency and voltage control are highly coupled, resulting in significant control limitations in balancing power quality optimization, local absorption rate improvement, and islanded operation resilience.

[0004] In summary, the technical problems existing in the relevant technologies need to be improved. Summary of the Invention

[0005] The main objective of this application is to propose a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, its control method, and related equipment, which can effectively reduce the temperature rise effect and capacity decay, while taking into account energy quality optimization, improving local consumption rate, and operational stability.

[0006] To achieve the above objectives, one aspect of this application proposes a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, the microgrid system comprising:

[0007] An AC network domain includes a wind power generation unit, an AC busbar, and a gravity energy storage device. The wind power generation unit is connected to the AC busbar and is used to transmit wind power output to the AC busbar. The gravity energy storage device is connected to the AC busbar and is used to store the wind power output transmitted by the AC busbar or to transmit gravity energy storage motor power to the AC busbar. The AC busbar directly supplies power to AC loads. The DC grid domain includes photovoltaic power generation devices, DC busbars, and DC energy storage devices. The photovoltaic power generation devices are connected to the DC busbars and are used to transmit photovoltaic power to the DC busbars. The DC energy storage devices are connected to the DC busbars and are used to store the photovoltaic power transmitted by the DC busbars or to transmit DC energy storage power to the DC busbars. The DC busbars directly supply power to DC loads. A bidirectional AC / DC interconnected converter, wherein one end of the bidirectional AC / DC interconnected converter is connected to the AC busbar, and the other end of the bidirectional AC / DC interconnected converter is connected to the DC busbar.

[0008] In some embodiments, the DC energy storage device includes: A supercapacitor energy storage device, wherein the supercapacitor energy storage device is used for first-level high-frequency power surge suppression and bus voltage stabilization; A lithium battery energy storage device, wherein the lithium battery energy storage device is used for second-level power tracking and energy transfer.

[0009] In some embodiments, the gravity energy storage device includes an electric motor, a mechanical transmission module, and a weight block; when the gravity energy storage device is charging, the electric motor converts the wind power output into mechanical energy, causing the mechanical transmission module to drive the weight block to rise; when the gravity energy storage device is generating electricity, the mechanical transmission module is controlled to drive the weight block to fall, causing the electric motor to convert the mechanical energy into electrical energy.

[0010] To achieve the above objectives, another aspect of this application proposes a control method for the aforementioned AC / DC coupled wind-solar hybrid energy storage microgrid system, the method comprising the following steps: The instantaneous output of wind power and photovoltaic power generation at the current time point is obtained, and the instantaneous output is used to characterize the actual active power output at the current time point. Obtain the total system load at the current time point, whereby the total system load is used to characterize the actual power required by the system at the current time point; The actual power generation status of the system at the current time point is determined based on the instantaneous output and the total system load. Determine the target operation strategy based on the actual power generation status of the system; The actual operation of the microgrid system is controlled according to the target operation strategy.

[0011] In some embodiments, determining the actual power generation state of the system at the current time point based on the instantaneous output and the total system load includes: When the instantaneous output is greater than the total system load, the actual power generation state of the system at the current time point is determined to be a surplus power generation state. When the instantaneous output is less than or equal to the total system load, the actual power generation status of the system at the current time point is determined to be an underpowered state.

[0012] In some embodiments, determining the target operating strategy based on the actual power generation state of the system includes: When the actual power generation state of the system is the surplus power generation state, a first operating strategy is selected as the target operating strategy; the first operating strategy includes a local consumption strategy, a cross-domain support strategy, or a protection and boundary constraint strategy. When the actual power generation state of the system is the insufficient power generation state, a second operating strategy is selected as the target operating strategy; the second operating strategy includes a first-level rapid support strategy, a second-level power allocation strategy, or a third-level predictive scheduling and coordinated control strategy.

[0013] In some embodiments, the local on-site disposal strategy includes: Within the AC network domain, the wind power output of the wind power generation device is controlled to prioritize supplying power to the AC load, and the remaining wind power output is used to charge the gravity energy storage device. Within the DC grid domain, the photovoltaic power generated by the photovoltaic power generation device is controlled to prioritize supplying power to the DC load, and the remaining photovoltaic power is used to charge the DC energy storage device.

[0014] In some embodiments, the cross-domain support policy includes: When the wind power output of the wind power generation device in the AC grid domain is lower than the power required by the AC load, the remaining photovoltaic power in the DC grid domain is controlled to supply power to the AC load through the bidirectional AC-DC interconnection converter. When the photovoltaic power generation in the DC grid domain is lower than the power required by the DC load, the remaining wind power output in the AC grid domain is controlled to supply power to the DC load through the bidirectional AC / DC interconnection converter.

[0015] To achieve the above objectives, another aspect of this application provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the method described above.

[0016] To achieve the above objectives, another aspect of the embodiments of this application proposes a computer-readable storage medium storing a computer program that, when executed by a processor, implements the methods described above.

[0017] To achieve the above objectives, another aspect of the embodiments of this application proposes a computer program product, including a computer program that, when executed by a processor, implements the aforementioned method.

[0018] The embodiments of this application include at least the following beneficial effects: This application provides a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, its control method, and related equipment. This scheme divides the microgrid system into an AC grid domain and a DC grid domain, and connects the AC grid domain and the DC grid domain through a bidirectional AC / DC interconnection converter. At the same time, wind power generation devices, AC buses, and gravity energy storage devices are set in the AC grid domain to achieve AC load connection within the AC domain. Photovoltaic power generation devices, DC buses, and DC energy storage devices are set in the DC grid domain to achieve DC load connection within the DC domain. This achieves frequency band separation and decoupling of AC / DC control targets, which can fundamentally reduce the risk of AC / DC linkage oscillation, effectively reduce temperature rise effect and capacity decay, and improve operational stability. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a wind-solar hybrid energy storage microgrid system based on AC / DC coupling provided in the embodiments of this application; Figure 2 This is a flowchart of a control method for a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, provided in an embodiment of this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.

[0021] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”

[0022] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application.

[0024] In related technologies, with the continuous increase in the proportion of clean energy, the distribution terminal is undergoing a structural transformation from "single power receiving" to "multiple entities, local balance, and two-way interaction." Especially in mountainous and hilly areas, although there are abundant wind and solar resources, they are generally constrained by geographical conditions and face physical bottlenecks such as weak grid support, long feeder paths, and limited short-circuit capacity. Against this backdrop, the randomness of new energy output can easily trigger power quality hazards such as frequency fluctuations, voltage flicker, and excessive harmonics; in addition, due to the limitation of transmission capacity, the phenomenon of wind and solar curtailment is also very serious. At the same time, the penetration rate of DC intrinsic loads (such as communication sites, data processing equipment, LED arrays, DC charging piles, etc.) is rapidly increasing, and the traditional all-AC power supply architecture is difficult to meet the demand for efficient energy supply due to multi-level energy efficiency conversion and harmonic superposition.

[0025] Existing microgrid technologies mostly follow a "full AC aggregation + single-point electrochemical energy storage" model. In this model, all power sources and loads are connected via the AC side, relying on lithium battery packs to passively respond to power fluctuations across the entire frequency range (from milliseconds to hours). While this single-dimensional regulation mechanism is advantageous for early deployment, in actual operation, it subjectes batteries to frequent high-frequency pulses and deep charge / discharge stress, leading to severe temperature rise and capacity decay. Under a weak spindle architecture, the AC side frequency and voltage control are highly coupled, resulting in significant control limitations in balancing power quality optimization, local absorption rate improvement, and islanded operation resilience.

[0026] In view of this, this application provides a wind-solar hybrid energy storage microgrid system based on AC / DC coupling, its control method and related equipment, which can effectively reduce the temperature rise effect and capacity decay, while taking into account energy quality optimization, improving local consumption rate and operational stability.

[0027] The embodiments of this application will be described in detail below with reference to the accompanying drawings: Reference Figure 1 This application provides a wind-solar hybrid energy storage microgrid system based on AC / DC coupling. The microgrid system includes an AC grid domain, a DC grid domain, and a bidirectional AC / DC interconnected converter 05. The AC grid domain includes a wind power generation device 01, an AC busbar 02, and a gravity energy storage device 04. The wind power generation device is connected to the AC busbar to supply wind power output; the gravity energy storage device is connected to the AC busbar to store the wind power output supplied by the AC busbar or to supply gravity energy storage motor power to the AC busbar; the AC busbar directly supplies power to the AC load 03.

[0028] Specifically, the wind power generation unit 01 has a built-in grid connection interface (including turbine-side control, grid-side inverter, and necessary filtering / transformer) to provide controllable active and reactive power to the AC busbar 02. The AC busbar 02 serves as the common AC-side busbar, collecting the wind power output (actual active power output at different wind speeds) of the wind power generation unit 01 and the gravity energy storage motor-side power of the gravity energy storage unit 04, and supplying power to the AC load 03. The AC load 03 includes electromechanical loads (such as pumps / fans / air conditioners), which are directly powered by the AC busbar 02. The gravity energy storage unit 04 includes an electric motor, a mechanical transmission module, and a weight block. The electric motor is directly connected to the AC busbar 02. When the gravity energy storage unit is charging, the electric motor converts the wind power output into mechanical energy, causing the mechanical transmission module to lift the weight block. When the gravity energy storage unit is generating electricity, the mechanical transmission module is controlled to lower the weight block, causing the electric motor to convert mechanical energy into electrical energy. The gravity energy storage device in this embodiment can achieve bidirectional power regulation of energy storage (rising) and power generation (falling), and undertake long-term energy transport and peak shaving at the third level (duration in min-h), with ramp rate, travel and mechanical power constraints.

[0029] It is understood that the DC grid domain includes photovoltaic power generation device 06, DC bus 07, and DC energy storage device; the photovoltaic power generation device is connected to the DC bus and is used to transmit photovoltaic power to the DC bus; the DC energy storage device is connected to the DC bus and is used to store the photovoltaic power transmitted by the DC bus or transmit DC energy storage to the DC bus; the DC bus directly supplies power to DC load 08.

[0030] Specifically, the photovoltaic power generation device 06 includes a photovoltaic array, equipped with an MPPT boost DC / DC converter, and directly connected to the DC bus 07 to provide controllable DC power. The DC bus 07 serves as a common DC-side collection bus, used to collect the DC power from the photovoltaic power generation device 06 and the DC energy storage device and supply power to the DC load 08. The DC load 08 includes intrinsically DC loads of electronic / information types (such as communication devices, servers, LEDs, DC fast charging, etc.), directly powered by the DC bus 07. The DC energy storage device includes a supercapacitor energy storage device 09 and a lithium battery energy storage device 10. The supercapacitor energy storage device 09 is equipped with a bidirectional DC / DC converter and voltage management, directly connected to the DC bus 07, and is used for the first level (duration in ms-s) of high-frequency power surge suppression and bus voltage regulation. The lithium battery energy storage device 10 is equipped with a bidirectional DC / DC converter and a BMS (battery management system), directly connected to the DC bus 07, and is used for the second level (duration in s-min) of power point tracking and energy transfer.

[0031] It is understood that one end of the bidirectional AC / DC interconnection converter 05 is connected to the AC bus 02, and the other end of the bidirectional AC / DC interconnection converter 05 is connected to the DC bus 07, so as to realize bidirectional energy exchange and power flow coordination between the AC and DC domains. In this embodiment, "direct access" means that each unit is electrically connected to the corresponding bus through its own body or the matching grid-connected / boost / bidirectional AC-AC or DC-DC interface, without any unnecessary cross-domain conversion stages in series.

[0032] based on Figure 1 The wind-solar hybrid energy storage microgrid system based on AC / DC coupling shown in the present application provides a corresponding control method. For example... Figure 2 As shown, the control method includes, but is not limited to, steps S210 to S250: Step S210: Obtain the instantaneous output of wind power and photovoltaic power at the current time node, wherein the instantaneous output is used to characterize the actual active power output at the current time node. Step S220: Obtain the total system load at the current time point, wherein the total system load is used to characterize the actual power required by the system at the current time point; Step S230: Determine the actual power generation status of the system at the current time node based on the instantaneous output and the total system load; Step S240: Determine the target operation strategy based on the actual power generation status of the system; Step S250: Control the actual operation of the microgrid system according to the target operation strategy.

[0033] It is understandable that when the instantaneous output exceeds the total system load, the actual power generation state of the system at the current time point is determined to be a surplus power generation state. In this surplus power generation state, this embodiment can select a first operating strategy as the target operating strategy. The first operating strategy includes a local consumption strategy, a cross-domain support strategy, or a protection and boundary constraint strategy. That is, under the first operating strategy, the microgrid system follows the strategy of "local load → local energy storage → cross-domain load → cross-domain energy storage" for energy allocation. Cross-domain power is only completed through the BIC and is constrained by the BIC capacity and bus voltage / frequency.

[0034] Specifically, the local consumption strategy in this domain refers to prioritizing the supply of wind power from wind turbines to AC loads within the AC grid domain, and using the surplus wind power to charge gravity energy storage devices (for lifting heavy objects); similarly, in the DC grid domain, prioritizing the supply of photovoltaic power from photovoltaic (PV) generators to DC loads, and using the surplus PV power to charge DC energy storage devices. MPPT (Maximum Power Point Tracking) is constrained by Vdc, Idc, and SOC windows. SOC (State of Charge) is a core parameter of energy storage systems (such as batteries), used for real-time monitoring and management of the battery's remaining charge state.

[0035] Cross-domain support strategy refers to the following: Under conditions of abundant sunshine and scarce wind (light or weak winds), when the wind power output of wind turbines in the AC grid is lower than the power required by the AC load (i.e., insufficient AC power), the remaining photovoltaic power in the DC grid is controlled to supply power to the AC load through a bidirectional AC / DC interconnected converter. This prioritizes supplying the AC load via DC bus → BIC → AC bus. If there is still remaining photovoltaic power after supplying the AC load, it is then used to charge the gravity energy storage device. Under conditions of abundant wind and scarce sunshine (cloudy or no sunshine), when the photovoltaic power in the DC grid is lower than the power required by the DC load (i.e., insufficient DC power), the remaining wind power output in the AC grid is controlled to supply power to the DC load through a bidirectional AC / DC interconnected converter. This prioritizes supplying the DC load via AC bus → BIC → DC bus. If there is still remaining wind power after supplying the DC load, it is then used to charge the lithium battery and supercapacitor.

[0036] Understandably, in the protection and boundary constraint strategy, for SOC / SOE, lithium batteries and overcapacitors are maintained within a safe range (e.g., SOC_min~SOC_max), and when limits are exceeded, the cross-domain power and local charging power are automatically adjusted. For gravity energy storage constraints, it is constrained by travel, mechanical power upper limit, and ramp rate to avoid frequent start-stop and excessive winding; charging is prohibited when the upper travel limit is reached. For BIC dual-target limits, BIC cross-domain power is constrained by both AC frequency / voltage and DC voltage dual targets and the current limiter to prevent excess power backflow from causing bus over-limit. For dead zone and hysteresis, power thresholds and hysteresis are set to avoid repeated small cross-domain exchanges that cause oscillations when there is excess power at the edge of the two domains.

[0037] It is understandable that when the instantaneous output is less than or equal to the total system load, the actual power generation state of the system at the current time point is determined to be an underpowered state. In this underpowered state, the microgrid system in this embodiment selects a second operating strategy as the target operating strategy. This second operating strategy includes a first-level rapid support strategy, a second-level power allocation strategy, or a third-level predictive scheduling and coordinated control strategy. That is, the microgrid system follows a strategy of "load priority, critical load priority, local priority, and health priority," with three levels of control working together to maintain steady-state operation and compensate for energy. Level 1 (ms-s): Fast voltage / frequency stabilization, suppressing high-frequency disturbances and sudden impacts; Second level (s-min): Intermediate frequency power distribution and SOC / SOE equalization to ensure continuous availability; Level 3 (min-h): Based on predicted long-term energy scheduling, arrange large-capacity, long-term gravity energy storage.

[0038] Understandably, in the first-level rapid support strategy, the control objectives on different sides are as follows: AC side: Quickly suppress frequency / voltage deviation and control frequency undershoot and voltage drop caused by short-term power shortage; DC side: Maintain the DC bus voltage Vdc within the target band, absorb / inject high-frequency power components; Cross-domain: Achieve the minimum necessary instantaneous power flow through BIC to avoid exceeding the limits of the two side buses.

[0039] The controlled objects and measurements are as follows: Supercapacitor bidirectional DC / DC converter, battery current inner loop, BIC current / power inner loop, inverter-side grid-connected control; Measurements: AC frequency / voltage, DC bus voltage Vdc, and various energy storage currents and terminal voltages.

[0040] The control algorithm and action sequence of the first-level rapid support strategy are as follows: On the AC side, Pf and QV drooping are used, and virtual inertia and active damping are superimposed: when the load increases or the source power drops sharply, the drooping ring automatically increases the active power output of the inverter, and the virtual inertia injects equivalent kinetic energy for a short time to suppress the rapid frequency drop (df / dt).

[0041] The DC side adopts an outer Vdc loop and an inner current loop: the outer loop detects the Vdc deviation to generate a power command, and the inner loop tracks at high speed, with the supercapacitor responding first and absorbing / releasing high-frequency components (ms-s).

[0042] BIC Fast Limiting: BIC uses both AC frequency and DC voltage as targets for current limiting, and only activates instantaneous cross-domain support when the target band cannot be maintained in the local domain, thus avoiding unnecessary energy travel.

[0043] The corresponding boundaries and protections are as follows: Supercapacitor voltage window and maximum power limit; low sensitivity response of the battery in this layer to avoid high-frequency stretching; DC / AC bus is equipped with over-limit fast switching and hysteresis to prevent back-and-forth jitter; Anti-saturation and anti-integral wind up ensure a rapid return to the linear region after large disturbances.

[0044] The interface with other layers in the first-level rapid support strategy is as follows: The "Power Received" and "Remaining Instantaneous Adjustment Margin (headroom)" are sent to the secondary level; The "predicted unsustainable duration" (such as the overcapacitance voltage about to reach the lower limit) is communicated to the secondary level, triggering the takeover of intermediate frequency resources.

[0045] Understandably, in the second-level power allocation strategy, the control objectives on different sides are as follows: Within the timescale of seconds to minutes, it smooths out persistent power gaps and maintains SOC / SOE within a safe window; The high-frequency pressure is transferred from the battery to the supercapacitor, and the long-term pressure is transferred to gravity storage (arranged by three levels).

[0046] The controlled objects and measurements are as follows: The bidirectional DC / DC converter of lithium battery and supercapacitor serves as the main actuator, and BIC serves as the cross-domain power regulator; Measurements: SOC / SOE, device temperature, permissible rate / climb limit, bus voltage and frequency, and the remaining instantaneous headroom sent from the first stage.

[0047] The control algorithm and action sequence are as follows: Load-source mismatch estimation: Calculate the net gaps ΔP_AC and ΔP_DC in the AC and DC domains, as well as the global gap ΔP.

[0048] Priority and allocation: Supercapacitors handle peak and short-bridge loads (S-level), and their output automatically decreases with time constant (avoiding battery replacement); Lithium batteries handle mid-frequency and continuous gap loads, and their power change rate is limited by ramping and follows the principle of minimizing cycle cost (suppressing deep / high-frequency cycling).

[0049] SOC / SOE Balance and Health Constraints: If the battery SOC is close to the lower limit, automatically increase the BIC cross-domain pull or trigger the level 3 gravity energy storage plan; if the overcapacitance voltage is close to the lower limit, the battery temporarily takes over more S-level power, while reducing the overcapacitance output slope.

[0050] BIC Dual-Objective Coordination: When a single-side bus approaches its limit (undervoltage / overvoltage), BIC guides cross-domain power flow to prioritize maintaining the target band of the bus; cross-domain power flow is simultaneously constrained by BIC capacity and bus limit values ​​to prevent "over-firing" from causing instability on the other side.

[0051] When necessary, perform an ordered power limiting / load shedding process: If the secondary assessment cannot maintain SOC and bus stability within a given time window (e.g., tens of seconds), perform power limiting / load shedding in the order of critical load → general load.

[0052] The boundaries and protection are as follows: Set SOC_min / SOC_max, ΔP / Δt upper limit, and temperature threshold; any constraint trigger will cause power allocation to be replanned. The second-level amplitude and slope commands are soft-limited to avoid conflict with the first-level fast loop; Set a hysteresis threshold for cross-domain power to avoid small bidirectional swings.

[0053] The interfaces with other layers are as follows: The "estimated duration of operation" (calculated from SOC and current power) will be fed back to Level 3; Request Level 3 to increase / decrease gravity storage output or adjust trans-domain power flow baseline in the next time window.

[0054] Understandably, in the third-level predictive scheduling cooperative control strategy, the corresponding control objective is as follows: On a minute to hourly scale, slow-dynamic resources such as gravity storage (04) and cross-domain power flow baselines are arranged to ensure energy sustainability and economy in subsequent periods; at the same time, an executable power trajectory and SOC target range are provided for the secondary stage.

[0055] The controlled objects and measurements / predictions are as follows: Targets: Gravity energy storage (power-stroke-speed limited), BIC cross-domain power flow baseline, photovoltaic MPPT power limiting strategy (if necessary); Forecasts: short- and medium-term forecasts for wind / solar / load, line and bus constraints, and energy storage health model (SOH).

[0056] The scheduling model and action sequence are as follows: Gravity storage delay response and constraint modeling: Rolling optimization (MPC): Using the future H (e.g., 30–120 min) as the prospect window, solve for decision variables (gravity storage power trajectory, BIC cross-domain power flow baseline, and photovoltaic power limiting trajectory when necessary), and update and distribute every Δt (e.g., 1–5 min).

[0057] Objective function (weights can be adaptive): Frequency / voltage deviation cost (reported back from secondary statistics); DC bus deviation cost; wind and solar curtailment cost; lithium battery cycle cost (depth × number of cycles × temperature coefficient); BIC power flow / loss penalty and line over-limit penalty.

[0058] Generate lower-level constraints and references: For Level 2: SOC target range and mid-term power boundary for battery / supercapacitor; For Level 1 / Level 2: Gravity storage power reference and BIC baseline (Level 1 still retains the right to fast deviation correction); For the source side: Photovoltaic power limiting / smoothing reference when necessary (to avoid Vdc overcharging or BIC overload).

[0059] The boundaries and protection are as follows: When forecast uncertainty increases (abnormal fluctuations, sensor loss), it is downgraded to a rule-based heuristic (such as fixed travel quota, fixed slope strategy) and the rolling step size is shortened; If the journey is near the boundary, arrange the return trip or release / absorption window in advance to avoid being "stuck".

[0060] The interface with the lower layer is as follows: Level 3 only issues slowly changing references and boundaries, leaving fast dynamics to Level 1 / 2; if Level 1 / 2 needs to deviate from Level 3's references to ensure safety, it can exceed its authority to execute, and Level 3 will re-optimize based on the feedback afterward.

[0061] Understandably, in handling mismatches and extreme operating conditions in microgrid systems, this embodiment can prioritize critical loads when both domains are simultaneously short, and implement orderly power limiting / load shedding according to the load classification sequence of "DC critical load → AC critical load → general load". The black start and reconnection process is as follows: overcapacitor power-on and regulated DC → lithium battery parallel connection to take over the base load → BIC closing to establish two buses → gravity energy storage gradually connects to the grid according to the ramp rate → wind / solar gradually connects.

[0062] For example, the actions performed under typical operating conditions are as follows: (1) Cloud shadows cause a sharp drop in photovoltaic power Level 1: Overcapacity immediately discharges to stabilize Vdc, AC side droop / inertia supports frequency; Level 2: Battery ramp-up control unit, BIC pulls part of the power from the AC side to supplement the DC side; Level 3: If the cloud cover is expected to persist, arrange for gravity energy storage to be gradually discharged and the BIC baseline to be raised, leaving a buffer for SOC in Level 2.

[0063] (2) Windless nights, increased load Level 1: Overcapacity suppresses the instantaneous drop caused by increased load; Level 2: Battery provides primary power, maintaining SOC at the target range during nighttime; Level 3: Gravity energy storage output is scheduled according to the nighttime curve, deep battery cycling is limited, and non-critical load power limiting is triggered when necessary.

[0064] (3) Connecting to the grid after the island is isolated. Level 1: Maintain the island's frequency / voltage and Vdc; Level 2: Ensure SOC / SOE does not exceed limits; Level 3: Plan gravity energy storage and BIC power flow, and connect to the grid only after meeting the synchronization criteria (angle difference / frequency difference / voltage difference) to avoid impact.

[0065] As can be seen from the above, the microgrid system and its control method according to the embodiments of this application have the following beneficial effects: 1. Technical effectiveness in addressing weak network conditions and fluctuation suppression in mountainous areas: (1) Significantly improved energy conversion efficiency: With the help of the direct integration and local consumption mechanism of source / load within the domain, cross-domain energy flow only needs to pass through a single BIC (interconnected converter) channel, which greatly reduces unnecessary intermediate conversion links and reduces system-level conversion losses and power heating.

[0066] (2) Enhanced absorption capacity and operational safety: The scheduling rule of "priority response in this region and flexible compensation across regions" has been established, which has greatly reduced the phenomenon of wind and solar curtailment caused by limited external transmission sections, and at the same time effectively shortened the duration of bus voltage and power exceeding the limit.

[0067] (3) Improved dynamic stability and power quality: Based on the frequency band separation and decoupling strategy of AC / DC control target, the BIC achieves precise coordination of the state of the two-sided bus, which reduces the risk of AC / DC side linkage oscillation from the root and ensures the stable operation in weak network environment.

[0068] Improved fault resilience and recovery efficiency: The pre-defined phased black start scheme significantly shortens the mean time to recovery (MTTR) from power failure to reconfiguration, effectively extending the supply cycle of critical loads under extreme conditions.

[0069] 2. Effects on system lifespan, quality, and environmental adaptability: (1) Efficient suppression of full-frequency fluctuations: A multi-level response system consisting of supercapacitor (high-frequency pulse), lithium battery (medium-frequency steady state) and gravity energy storage (low-frequency long time) has been formed, ensuring the smoothness of output power under complex meteorological conditions and achieving full coverage of microsecond to hourly disturbances.

[0070] (2) Physical isolation of harmonic pollution: The domain architecture is used to achieve the domain-limited management of power quality hazards on the AC and DC sides, prevent DC side fluctuations from being directly injected into the AC network, and suppress the spread of AC side flicker to the DC bus, which significantly reduces the investment cost of external filtering devices.

[0071] (3) Extended service life of energy storage assets: By explicitly reducing the frequency of high-frequency response and the depth of deep charging and discharging of lithium batteries, their temperature rise performance and equivalent cycle stress are significantly optimized, thereby reducing the operation and maintenance costs and battery replacement frequency throughout the entire life cycle.

[0072] (4) Flexibility and economy of project deployment: Gravity energy storage scheme makes full use of the geographical features of mountainous areas, has low dependence on water resources and flat land, and supports modular expansion and "connection as you build" construction mode, which effectively alleviates the peak investment pressure in the early stage of the project and has excellent terrain adaptability.

[0073] This application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the above-described method. This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.

[0074] It is understood that the content of the above method embodiments is applicable to this device embodiment. The specific functions implemented by this device embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0075] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0076] It is understood that the content of the above method embodiments is applicable to this storage medium embodiment. The specific functions implemented in this storage medium embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0077] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0078] It is understood that the content of the above method embodiments is applicable to the embodiments of this program product. The specific functions implemented by the embodiments of this program product are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0079] The embodiments described in this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. As those skilled in the art will know, with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0080] Those skilled in the art will understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of this application, and may include more or fewer steps than shown, or combine certain steps, or different steps.

[0081] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0082] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0083] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0084] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0085] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0086] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0087] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0088] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0089] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of the claims of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the claims of the present application.

Claims

1. A wind-solar hybrid energy storage microgrid system based on AC / DC coupling, characterized in that, The microgrid system includes: An AC network domain includes a wind power generation unit, an AC busbar, and a gravity energy storage device. The wind power generation unit is connected to the AC busbar and is used to transmit wind power output to the AC busbar. The gravity energy storage device is connected to the AC busbar and is used to store the wind power output transmitted by the AC busbar or to transmit gravity energy storage motor power to the AC busbar. The AC busbar directly supplies power to AC loads. The DC grid domain includes photovoltaic power generation devices, DC busbars, and DC energy storage devices. The photovoltaic power generation devices are connected to the DC busbars and are used to transmit photovoltaic power to the DC busbars. The DC energy storage devices are connected to the DC busbars and are used to store the photovoltaic power transmitted by the DC busbars or to transmit DC energy storage power to the DC busbars. The DC busbars directly supply power to DC loads. A bidirectional AC / DC interconnected converter, wherein one end of the bidirectional AC / DC interconnected converter is connected to the AC busbar, and the other end of the bidirectional AC / DC interconnected converter is connected to the DC busbar.

2. The microgrid system according to claim 1, characterized in that, The DC energy storage device includes: A supercapacitor energy storage device, wherein the supercapacitor energy storage device is used for first-level high-frequency power surge suppression and bus voltage stabilization; A lithium battery energy storage device, wherein the lithium battery energy storage device is used for second-level power tracking and energy transfer.

3. The method according to claim 1, characterized in that, The gravity energy storage device includes an electric motor, a mechanical transmission module, and a weight block. When the gravity energy storage device is charging, the electric motor converts the wind power output into mechanical energy, causing the mechanical transmission module to lift the weight block. When the gravity energy storage device is generating electricity, the mechanical transmission module is controlled to lift the weight block, causing the electric motor to convert the mechanical energy into electrical energy.

4. A control method applied to the wind-solar hybrid energy storage microgrid system based on AC-DC coupling as described in any one of claims 1-3, characterized in that, The method includes the following steps: The instantaneous output of wind power and photovoltaic power generation at the current time point is obtained, and the instantaneous output is used to characterize the actual active power output at the current time point. Obtain the total system load at the current time point, whereby the total system load is used to characterize the actual power required by the system at the current time point; The actual power generation status of the system at the current time point is determined based on the instantaneous output and the total system load. Determine the target operation strategy based on the actual power generation status of the system; The actual operation of the microgrid system is controlled according to the target operation strategy.

5. The method according to claim 2, characterized in that, Determining the actual power generation status of the system at the current time point based on the instantaneous output and the total system load includes: When the instantaneous output is greater than the total system load, the actual power generation state of the system at the current time point is determined to be a surplus power generation state. When the instantaneous output is less than or equal to the total system load, the actual power generation status of the system at the current time point is determined to be an underpowered state.

6. The method according to claim 5, characterized in that, The determination of the target operation strategy based on the actual power generation status of the system includes: When the actual power generation state of the system is the surplus power generation state, a first operating strategy is selected as the target operating strategy; the first operating strategy includes a local consumption strategy, a cross-domain support strategy, or a protection and boundary constraint strategy. When the actual power generation state of the system is the insufficient power generation state, a second operating strategy is selected as the target operating strategy; the second operating strategy includes a first-level rapid support strategy, a second-level power allocation strategy, or a third-level predictive scheduling and coordinated control strategy.

7. The method according to claim 6, characterized in that, The local on-site disposal strategy includes: Within the AC network domain, the wind power output of the wind power generation device is controlled to prioritize supplying power to the AC load, and the remaining wind power output is used to charge the gravity energy storage device. Within the DC grid domain, the photovoltaic power generated by the photovoltaic power generation device is controlled to prioritize supplying power to the DC load, and the remaining photovoltaic power is used to charge the DC energy storage device.

8. The method according to claim 7, characterized in that, The cross-domain support strategy includes: When the wind power output of the wind power generation device in the AC grid domain is lower than the power required by the AC load, the remaining photovoltaic power in the DC grid domain is controlled to supply power to the AC load through the bidirectional AC-DC interconnection converter. When the photovoltaic power generation in the DC grid domain is lower than the power required by the DC load, the remaining wind power output in the AC grid domain is controlled to supply power to the DC load through the bidirectional AC / DC interconnection converter.

9. An electronic device / computer apparatus, characterized in that, include: At least one processor; At least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method as described in any one of claims 4 to 8.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the method of any one of claims 4 to 8.

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