Sustainable Aviation Fuel Production System and Method Based on Wind-Solar AC / DC Microgrids

Abstract

This invention proposes a sustainable aviation fuel production system and method based on a wind-solar AC / DC microgrid. The system includes: a wind power generation module that converts wind energy into constant-voltage, constant-frequency AC and DC power; an AC bus connected to the wind power generation module to obtain AC power; a photovoltaic power generation module that converts solar energy into DC power; a DC bus connecting the photovoltaic and wind power generation modules to obtain DC power; a bidirectional converter connected between the AC and DC buses for bidirectional conversion between AC and DC power; a carbon dioxide electroreduction unit and an electrolytic hydrogen production unit connected to the DC bus as DC loads; and motor drive equipment and / or heating equipment in the carbon dioxide capture unit, Fischer-Tropsch synthesis unit, and hydrodistillation unit connected to the AC bus as AC loads; and an energy dispatch module that regulates the power flow between the AC and DC buses through the bidirectional converter. This invention can improve energy utilization efficiency and system economy.

Description

Technical Field

[0001] This invention relates to the field of renewable energy utilization and chemical production system technology, and in particular to a sustainable aviation fuel preparation system and method based on wind and solar AC / DC microgrids. Background Technology

[0002] In recent years, the global aviation industry has faced increasingly stringent carbon emission reduction constraints. Regulations such as the International Civil Aviation Organization's (ICAO) Carbon Offset and Reduction in International Aviation (CORSIA) program and the European Union's ReFuelEU Aviation program require airlines to gradually increase the blending ratio of sustainable aviation fuel (SAF) and ultimately achieve net-zero emissions. Meanwhile, the United States, the United Kingdom, Japan, and China have successively introduced policies such as the "Clean Fuel Standards" and "Green Aviation Roadmaps," providing policy guidance for the industrialization of renewable liquid fuels.

[0003] Currently, the main SAF (Self-Produced Air Fuel) technology routes include the hydrogenated ester and fatty acid route (HEFA), the alcohol-to-fuel (ATJ) route, and the power-to-liquid (PtL) route. Among them, the PtL route is considered one of the most promising solutions because it uses carbon dioxide and renewable electricity as core feedstocks and can achieve carbon neutrality throughout its entire life cycle. A typical PtL process chain includes: direct air carbon capture (DAC) to separate and obtain high-purity carbon dioxide from the air; electrochemical reduction of carbon dioxide (eCO2RR) to co-produce hydrogen and carbon monoxide using renewable electricity and blend them into syngas; electrolysis of water to produce hydrogen (PEM) to decompose water into high-purity hydrogen using renewable electricity; Fischer-Tropsch synthesis (FT) to convert syngas into a mixture of long-chain hydrocarbons, including Fischer-Tropsch waxes and Fischer-Tropsch oils, under the action of a catalyst; and hydrorefining and fractionation to produce aviation fuel products that meet ASTM D7566 standards.

[0004] However, the commercial application of this route faces a series of key challenges stemming from both its inherent characteristics and external conditions. The PtL process is extremely energy-intensive, requiring approximately 15 to 18 MWh of electricity to produce 1 ton of SAF, with about 60% used for water electrolysis to produce hydrogen and carbon dioxide electroreduction, and about 30% used for direct air carbon capture, Fischer-Tropsch synthesis, and hydrorefining processes. Although the abundant wind and solar resources in Northwest China (such as Inner Mongolia, Gansu, and Xinjiang) can provide highly competitive green electricity at a competitive cost per kilowatt-hour, thus alleviating the cost pressure from high energy consumption, the wind and solar-powered energy supply model itself introduces severe volatility and intermittency issues, posing a fundamental challenge to chemical production systems that require continuous and stable operation.

[0005] First, the dramatic fluctuations and discontinuous supply of wind and solar power place high demands on the operational flexibility of process equipment. On the one hand, frequent start-ups and shutdowns of units such as absorption towers and regeneration towers in direct air carbon capture systems shorten equipment lifespan, while achieving flexibility through modular redundancy configurations significantly increases initial investment. On the other hand, the reaction temperature and pressure conditions of core reaction sections such as Fischer-Tropsch synthesis and hydrorefining make it difficult to adjust their loads quickly and frequently, and the thermal stress of equipment materials and process safety limits their ability to cope with fluctuations. Although electrochemical units such as electrolyzers and carbon dioxide electroreduction inherently possess the potential for rapid load adjustment, as intermediate sections, their operational flexibility is severely constrained by the rigid processes upstream and downstream, preventing them from independently mitigating power fluctuations.

[0006] Secondly, existing PtL demonstration systems mostly adopt the traditional power supply architecture of "centralized inverter – boost-grid connection – re-rectification – load distribution," resulting in long energy conversion links and high losses. Specifically, the DC power generated by photovoltaics needs to be converted to AC power by an inverter (DC / AC) and connected to the AC bus; the frequency conversion AC power output from wind turbines also needs to be rectified to DC by a rectifier (AC / DC), and then converted to industrial frequency AC by an inverter (DC / AC) and connected to the same AC bus. Afterward, the bus power needs to be boosted by a transformer before being distributed to various loads. For inherently DC loads such as electrolyzers and carbon dioxide electroreduction reactors, DC power needs to be converted again from the AC bus by a separate rectifier (AC / DC). The efficiency of each stage of AC / DC or DC / AC conversion in this process is typically between 95% and 98%, and after multiple stages of conversion, the overall electrical efficiency of the system may only be 85% to 90%. In addition, multiple power conversions introduce a series of problems such as increased harmonic interference, increased equipment size and cost, and difficulty in managing centralized heat loss, which together form a technical dilemma of "high power consumption, low efficiency, and complex structure".

[0007] Furthermore, during periods of insufficient wind and solar power output, the entire production system is often forced to operate at reduced load or even shut down, resulting in low utilization rates of expensive chemical equipment, significantly extending the capital recovery cycle, and severely impacting the project's economic viability. Finally, from a product certification perspective, according to international green certification systems such as the Renewable Energy Sources of Non-Bio Fuels (RFNBO) standard under the EU Renewable Energy Directive, SAF production must meet stringent conditions regarding the additionality, geographical relevance, and temporal relevance of renewable electricity. Due to the low regional mutual recognition of the proportion of green electricity in the power grid, non-directly connected renewable energy projects are difficult to certify. This requires PtL plants to establish a power supply system directly coupled to renewable power generation equipment and capable of demonstrating real-time matching.

[0008] In summary, how to construct a novel system architecture that can efficiently integrate fluctuating renewable energy sources with continuous SAF preparation processes, while ensuring the stable operation of core chemical processes and maximizing energy utilization efficiency and system economy, has become a key technical bottleneck that must be overcome to promote the commercialization of this technology. Summary of the Invention

[0009] The purpose of this invention is to provide a sustainable aviation fuel preparation system and method based on wind-solar AC / DC microgrids to solve the above-mentioned problems. By constructing a wind-solar complementary energy input, an AC / DC dual-bus coupling structure, and energy integration of electrochemical and thermochemical processes, continuous and stable aviation fuel synthesis under renewable energy conditions is achieved, thereby improving energy utilization efficiency and system economy.

[0010] This invention proposes a sustainable aviation fuel production system based on wind-solar AC / DC microgrids, comprising:

[0011] Wind power generation components convert wind energy into constant voltage and constant frequency alternating current and direct current;

[0012] The AC busbar connects to the wind turbine generator components to obtain AC power.

[0013] Photovoltaic power generation modules convert sunlight into direct current.

[0014] The DC bus connects the photovoltaic power generation modules and the wind power generation modules to obtain DC power.

[0015] A bidirectional converter is connected between the AC bus and the DC bus to perform bidirectional conversion between AC and DC power.

[0016] The sustainable aviation fuel production module converts carbon dioxide into aviation fuel. It includes five process units: a carbon dioxide capture unit for capturing carbon dioxide from the air, a carbon dioxide electroreduction unit for electrolyzing carbon dioxide and water to generate syngas from carbon monoxide and hydrogen, an electrolysis hydrogen production unit for electrolyzing water to generate hydrogen, a Fischer-Tropsch synthesis unit for converting syngas into oil and wax, and a hydrodistillation unit for converting oil and wax into aviation fuel through catalytic hydrogenation and distillation. The carbon dioxide electroreduction unit and the electrolysis hydrogen production unit are connected to the DC bus as DC loads, while the motor drive equipment and / or heating equipment in the carbon dioxide capture unit, the Fischer-Tropsch synthesis unit, and the hydrodistillation unit are connected to the AC bus as AC loads.

[0017] The energy dispatch module, based on the electrical status of the DC bus and AC bus and / or the load requirements of each process unit, regulates the power flow between the AC bus and DC bus through a bidirectional converter.

[0018] In one embodiment, the wind power generation component includes a doubly-fed induction generator;

[0019] The stator side of the doubly-fed induction generator is directly connected to the AC bus, and it outputs constant voltage and constant frequency AC power.

[0020] The rotor side of the doubly fed induction generator is connected to the DC bus via a rotor-side converter, which converts AC power into DC power.

[0021] In one embodiment, the sustainable aviation fuel production system based on wind-solar AC / DC microgrids further includes an MPPT controller and a DC / DC boost converter;

[0022] The MPPT controller connects to the photovoltaic power generation module, calculates the maximum power point of the photovoltaic power generation module, and outputs control commands;

[0023] The DC / DC boost converter maintains the operating point of the photovoltaic power generation module at the maximum power point according to the instructions output by the MPPT controller, and boosts the output voltage of the photovoltaic power generation module to a voltage level that matches the DC bus.

[0024] In one embodiment,

[0025] The electrolyzers of the carbon dioxide electroreduction unit and the electrolytic hydrogen production unit draw power from the DC bus via a DC / DC step-down converter;

[0026] The motor-driven equipment includes at least one of a compressor, a fan, and a circulating pump, and draws power from the AC bus via a frequency converter and a transformer.

[0027] The heating equipment includes at least one of an electric steam generator and a heat pump, and draws power from the AC bus via a transformer.

[0028] In one embodiment, the sustainable aviation fuel production system based on wind and solar AC / DC microgrids further includes a chemical energy storage module, which is connected to the DC bus via a bidirectional DC / DC converter to store excess electrical energy of the DC bus or discharge it when needed to maintain the voltage stability of the DC bus.

[0029] In one embodiment, the sustainable aviation fuel production system based on wind-solar AC / DC microgrids further includes a gas buffer module, which includes a carbon dioxide storage tank and / or a syngas storage tank.

[0030] The carbon dioxide storage tank is located between the carbon dioxide capture unit and the carbon dioxide electroreduction unit and is used to store carbon dioxide.

[0031] The syngas storage tank is located between the carbon dioxide electroreduction unit and the Fischer-Tropsch synthesis unit, and is used to store syngas composed of carbon monoxide and hydrogen.

[0032] In one embodiment, the energy dispatch module performs multi-level coordinated control to keep the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit within a set range, including a primary control unit, a secondary coordinated control unit, and a tertiary optimization control unit.

[0033] The primary control unit includes an embedded controller that performs voltage-current dual closed-loop control of the DC bus and / or AC bus, autonomous power distribution control based on droop curves, virtual impedance control, and current limiting or disconnection protection when the transient load of the DC load or AC load exceeds the limit, based on the DC bus electrical signal, DC load signal, AC bus electrical signal and / or AC load signal.

[0034] The secondary coordination control unit regulates the power flow between the AC bus and the DC bus by controlling the bidirectional converter, thereby maintaining the stability of the AC bus frequency and / or the DC bus voltage.

[0035] The three-stage optimization control unit uses historical and real-time data and time series models to predict wind and solar power output for future periods. Based on the prediction results, and with the goal of minimizing power curtailment while keeping the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit within a set range, it generates a preset power transmission plan for the bidirectional converter, a charging and discharging plan for the chemical energy storage module, a charging and discharging plan for the gas buffer module, and / or a power plan for the DC load.

[0036] This invention also proposes a sustainable aviation fuel production method based on a wind-solar AC / DC microgrid. The method is applied to the sustainable aviation fuel production system based on a wind-solar AC / DC microgrid as described above, and includes the following steps:

[0037] Wind energy is captured using wind power generation components to generate alternating current;

[0038] Photovoltaic power generation modules capture solar energy to generate direct current.

[0039] Connect the AC power generated by wind power generation to the AC bus, and connect the DC power generated by photovoltaic power generation to the DC bus.

[0040] The carbon dioxide electroreduction unit and the electrolytic hydrogen production unit in the sustainable aviation fuel preparation module are connected to the DC bus as DC loads, and the motor drive equipment and / or heating equipment in the carbon dioxide capture unit, Fischer-Tropsch synthesis unit and hydrodistillation unit in the sustainable aviation fuel preparation module are connected to the AC bus as AC loads.

[0041] The energy dispatch module controls the bidirectional converter to regulate the power flow between the AC bus and the DC bus based on the electrical status of the DC bus and the AC bus and / or the load demand of each process unit in the sustainable aviation fuel preparation module, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range.

[0042] In one embodiment, the energy dispatch module controls the bidirectional converter to regulate the power flow between the AC bus and the DC bus based on the electrical status of the DC bus and the AC bus and / or the load demand of each process unit in the sustainable aviation fuel preparation module, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range. Specifically, this includes:

[0043] Within a millisecond period, the embedded controller performs voltage-current dual closed-loop control of the DC bus and / or AC bus, autonomous power distribution control based on the droop curve, virtual impedance control, and current limiting or disconnection protection when the transient load of the DC load or AC load exceeds the limit, based on the DC bus electrical signal, DC load signal, AC bus electrical signal and / or AC load signal.

[0044] Within a second-level cycle, the power flow between the AC bus and the DC bus is regulated by controlling the bidirectional converter to maintain the stability of the AC bus frequency and / or the DC bus voltage.

[0045] Within a minute or hourly cycle, based on historical and real-time data, a time series model is used to predict the wind and solar power output for future periods. Based on the prediction results, with the goal of minimizing power curtailment and ensuring that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range, a preset power transmission plan for the bidirectional converter, a charging and discharging plan for the chemical energy storage module, a charging and discharging plan for the gas buffer module, and / or a power plan for the DC load are generated.

[0046] In one embodiment,

[0047] When photovoltaic output is dominant and wind power output is insufficient, the electrolysis hydrogen production unit and carbon dioxide electroreduction unit are driven by DC bus, and the DC power is converted into AC power by rotor-side converter to smooth the AC output of wind power generation components. The surplus power is supplied to AC bus by bidirectional converter and / or stored in chemical energy storage module.

[0048] When wind power output is dominant and photovoltaic output is insufficient, the carbon dioxide capture unit, Fischer-Tropsch synthesis unit and hydrodistillation unit are driven by the AC bus, and the AC power is supplied to the DC bus through the rotor-side converter and / or bidirectional converter. The DC bus is compensated by the discharge through the chemical energy storage module, and / or the stored carbon dioxide and / or synthesis gas is released through the gas buffer module.

[0049] When wind and solar power outputs are sufficient, increase the operating load of each process unit in the sustainable aviation fuel preparation module, and store carbon dioxide and / or syngas through the gas buffer module, and / or store surplus electrical energy through the chemical energy storage module.

[0050] When wind and solar power output is insufficient, the stored carbon dioxide and / or synthesis gas are released through the chemical energy storage module and / or the gas buffer module, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit can continue to operate within the set range.

[0051] Compared with existing technologies, the beneficial effects of the sustainable aviation fuel production system and method based on wind-solar AC / DC microgrids of the present invention are as follows:

[0052] 1) This invention utilizes an architecture where wind and solar power generation are connected to the AC bus and DC bus respectively. Through the core strategy of direct DC power supply to native loads and on-site AC power extraction, it optimizes energy flow. Specifically, photovoltaic power generation, PEM electrolysis, carbon dioxide electrochemical reduction, and chemical energy storage modules are uniformly configured on the DC bus side, enabling the shortest path for DC power transmission from the generation end to the reaction load end, avoiding the cumulative energy loss caused by the traditional multi-stage "DC→AC→DC" conversion. Simultaneously, the stator of the doubly-fed induction generator (DFIG) is directly connected to the AC bus, allowing AC loads such as wind turbines, compressors, and electric heaters to directly draw power without additional rectification or inversion stages. This not only increases the overall electrical efficiency of the system from approximately 85-90% under the traditional architecture to a higher level but also effectively reduces the number, capacity, and related investment of inverters and rectifiers, lowering system complexity and maintenance costs.

[0053] 2) This invention unifies the flexible loads with rapidly adjustable power, such as the electrolyzer, electrochemical carbon dioxide reduction reactor, and energy storage system of the electrolytic hydrogen production unit, on the DC bus side, placing them in the same electrical domain as photovoltaic power generation, which has highly volatile characteristics. This allows the instantaneous power fluctuations generated by wind and solar power generation to be quickly responded to and absorbed by the flexible loads in the same electrical domain, thereby decoupling the fluctuating power source from downstream processes (such as Fischer-Tropsch synthesis and hydrodistillation) that have high requirements for power supply stability, and ensuring stable power supply for key continuous chemical processes under fluctuating wind and solar power conditions.

[0054] 3) This invention employs a doubly fed induction generator (DFIG) with its rotor side connected to the DC bus via a rotor-side converter (RSC), making the DFIG rotor circuit an electromagnetic power buffer. When wind speed disturbances occur, the resulting mechanical power fluctuations are first absorbed or released by the rotor side and buffered on the DC side via the RSC. This ensures that the electrical power output from the DFIG stator side to the AC bus remains smooth and stable, protecting continuous process equipment sensitive to power fluctuations, such as the carbon dioxide capture unit's absorption tower, Fischer-Tropsch synthesis reactor, and hydrogenation section, from periodic shocks, significantly improving the reliability, safety, and service life of the equipment.

[0055] 4) This invention buffers and decouples fluctuations in wind and solar power output from two physical scales: electrical power and material flow rate, by setting up chemical energy storage modules (such as lithium batteries or flow batteries) and gas buffering units (syngas storage tanks and / or carbon dioxide storage tanks). The chemical energy storage modules are responsible for power balance, while the gas buffering units are responsible for material balance. This dual buffering mechanism enables continuous operation sections such as carbon dioxide capture, Fischer-Tropsch synthesis, and hydrogenation to maintain operation within the rated operating range even under conditions of drastic fluctuations in wind and solar power output. This is achieved through the charging and discharging of energy storage and the feeding and discharging of materials into and out of the storage tanks, effectively avoiding frequent start-ups, shutdowns, and load reductions caused by upstream fluctuations in traditional solutions. This reduces the resulting additional energy consumption, equipment fatigue, and safety risks.

[0056] 5) This invention employs a hierarchical, progressive energy management system covering time scales from milliseconds to hours. Millisecond-level primary local control relies on the local controllers (DSP / FPGA) of each converter, executing dual-loop voltage and current control, droop control, virtual impedance control, and rapid protection, forming the cornerstone of system stability. Second-level secondary coordination control compensates for steady-state deviations caused by primary control and rapidly coordinates power exchange between AC and DC buses, manages energy storage charging and discharging, and smooths short-term fluctuations. Minute- to hourly-level tertiary global optimization control (EMS) predicts wind and solar power output and process loads based on time series models (such as LSTM and XGBoost) and optimizes the scheduling of system resources using a feedforward approach. These three levels of control work collaboratively to achieve full-cycle dynamic management of the entire process, including wind and solar power generation, energy storage, electrolysis, reduction, capture, and synthesis, significantly improving the system's adaptability, stability, and overall operating efficiency under strong fluctuation scenarios.

[0057] 6) This invention, by constructing an independently operating wind-solar microgrid directly connected to chemical loads and combining it with an hourly-precision energy management and data traceability system, technically meets the stringent requirements of the EU Renewable Energy Sources Directive (RED II) for non-biological renewable fuel sources (RFNBO), as well as the stringent requirements of the International Aviation Carbon Offset and Reduction Initiative (CORSIA) for the additionality, geographical relevance, and temporal relevance of renewable electricity. The system provides accurate electricity metering and full-process operational data traceability, offering solid technical support and compliance proof for obtaining internationally recognized green certifications (such as ISCC and RSB) for the produced sustainable aviation fuel (SAF), significantly enhancing the product's market competitiveness.

[0058] 7) This invention improves the system's economic efficiency from multiple dimensions through the organic synergy of multiple technologies, such as electrical link simplification, flexible load centralized management, continuous operation of downstream sections, and synergistic optimization of energy storage / gas storage scale. It increases the SAF output per unit of renewable electricity input, reduces the comprehensive power consumption and cost per kilowatt-hour of producing each ton of SAF, reduces capacity loss caused by equipment start-up, shutdown, and load reduction, optimizes the configuration scale and utilization rate of expensive assets such as energy storage, effectively shortens the investment recovery cycle of the entire device, and improves the overall economic efficiency and commercial feasibility of the project. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of a sustainable aviation fuel production system based on a wind-solar AC / DC microgrid according to an embodiment of the present invention;

[0060] Figure 2 This is a schematic diagram of a doubly-fed induction generator connected to an AC / DC bus according to an embodiment of the present invention;

[0061] Figure 3 This is a schematic diagram of a photovoltaic power generation module connected to a DC bus according to an embodiment of the present invention;

[0062] Figure 4 This is a hierarchical control architecture diagram of an energy scheduling module according to an embodiment of the present invention;

[0063] Figure 5 This is a graph showing the daily output coefficients of wind power and photovoltaic power in Northwest China according to an embodiment of the present invention.

[0064] Figure Labels

[0065] 1. Wind power generation module; 2. Photovoltaic power generation module; 3. AC bus; 4. DC bus; 5. Bidirectional converter; 61. Carbon dioxide capture unit; 62. Carbon dioxide electroreduction unit; 63. Electrolysis hydrogen production unit; 64. Fischer-Tropsch synthesis unit; 65. Hydrogen distillation unit; 7. Chemical energy storage module. Detailed Implementation

[0066] To make the objectives, technical solutions, and advantages of this invention more readily understood, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that while many specific details are set forth in the following description to provide a thorough understanding of the invention, the invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the invention; therefore, the invention is not limited to the specific embodiments disclosed below.

[0067] Secondly, the phrase "an embodiment" or "a particular embodiment" in this application refers to a specific feature, structure, or characteristic that can be included in at least one implementation of the present invention. The phrases "in one embodiment" and "a particular embodiment" appearing in different places in this specification do not all refer to the same embodiment, nor are they embodiments that are mutually exclusive, either alone or selectively, with other embodiments. The terms "comprising" or "including" indicate the presence of the claimed feature but do not exclude the presence of one or more other features. The term "and / or" as used in this application includes any and all combinations of one or more of the related listed items.

[0068] This invention proposes a sustainable aviation fuel production system based on a wind-solar AC / DC microgrid. (See [link to relevant documentation]). Figure 1The system includes a wind turbine generator (1), an AC bus (3), a photovoltaic (PV) generator (2), a DC bus (4), a bidirectional converter (5), a sustainable aviation fuel production module, and an energy dispatch module. The wind turbine generator (1) converts wind energy into constant-voltage, constant-frequency AC and DC power. The AC bus (3) connects to the wind turbine generator to obtain stable AC power. The PV generator (2) converts solar energy into DC power. The DC bus (4) connects the PV generator and the wind turbine generator to obtain DC power. The bidirectional converter (5) connects between the AC bus and the DC bus, performing bidirectional conversion between AC and DC power. The sustainable aviation fuel production module, used to convert carbon dioxide into aviation fuel, includes five process units: a carbon dioxide capture unit (DAC) 61 for capturing carbon dioxide from the air; a carbon dioxide electroreduction unit (eCO2RR) 62 for electrolyzing carbon dioxide and water to produce syngas from carbon monoxide and hydrogen; an electrolytic hydrogen production unit (PEM) 63 for electrolyzing water to produce hydrogen; a Fischer-Tropsch synthesis unit (FT) 64 for converting syngas into oil and wax; and a hydrodistillation unit 65 for converting oil and wax into aviation fuel through catalytic hydrogenation and subsequent distillation. The carbon dioxide electroreduction unit and the electrolytic hydrogen production unit are connected to the DC bus as DC loads, while the motor-driven equipment (such as compressors, circulating pumps, and fans) and / or heating equipment (electric steam generators, such as resistance or electrode electric steam boilers) in the carbon dioxide capture unit, Fischer-Tropsch synthesis unit, and hydrodistillation unit are connected to the AC bus as AC loads. The energy dispatch module, based on the electrical status of the DC and AC buses and / or the load requirements of each process unit, regulates the power flow between the AC and DC buses by controlling the power flow direction and magnitude of the bidirectional converter, thereby achieving power balance between the AC and DC domains. Specifically, the energy dispatch module monitors the DC voltage and / or current of the DC bus, and the AC voltage and / or frequency of the AC bus, compares the monitored values ​​with the rated values ​​of the corresponding buses, generates control signals based on the comparison results, and drives the bidirectional converter to perform power conversion to eliminate or reduce the power difference between the DC and AC buses.

[0069] One embodiment of the wind power generation component of the present invention includes a doubly fed induction generator (DFIG wind turbine), see [link to relevant documentation]. Figure 2 The stator side of the doubly fed induction generator is directly connected to the AC bus, outputting constant frequency and constant voltage AC power, so that the AC bus can obtain stable AC power. The rotor side is connected to the DC bus through a rotor-side converter (RSC, as an AC / DC rectifier). The rotor-side converter converts AC power into DC power, absorbs wind power fluctuations through rotor-side power regulation, and buffers the fluctuating power to the DC bus side.

[0070] One embodiment of the sustainable aviation fuel production system based on a wind-solar AC / DC microgrid of the present invention further includes an MPPT (maximum power point tracking) controller and a DC / DC boost converter, see [link to relevant documentation]. Figure 3 The MPPT controller connects to the photovoltaic (PV) module, continuously monitoring its output voltage and current. It calculates the PV module's maximum power point in real-time using algorithms (such as perturbation observation or incremental conductance methods) and outputs control commands. The DC / DC boost converter connects to both the PV module and the DC bus. Based on the MPPT controller's commands, it adjusts its duty cycle to maintain the PV module's operating point at its maximum power point and boosts its output voltage to a level matching the DC bus. Specifically, the DC / DC boost converter uses fast-switching power devices (such as MOSFETs) to change the circuit's equivalent impedance, converting the PV module's power into a stable voltage level that meets the DC bus requirements.

[0071] In one embodiment of the present invention, the electrolyzer of the carbon dioxide electroreduction unit and the electrolytic hydrogen production unit draws power from the DC bus via a DC / DC step-down converter. The motor drive equipment includes at least one of a compressor, a fan, and a circulating pump, and draws power from the AC bus via a frequency converter (VFD) and a transformer. The heating equipment includes at least one electric heater of an electric steam generator and a heat pump, and draws power from the AC bus via a transformer.

[0072] An embodiment of the sustainable aviation fuel production system based on a wind-solar AC / DC microgrid of the present invention further includes a chemical energy storage module 7. The chemical energy storage module 7 is connected to the DC bus via a bidirectional DC / DC converter to store excess electrical energy of the DC bus or discharge it when needed to maintain the voltage stability of the DC bus.

[0073] An embodiment of the sustainable aviation fuel production system based on a wind-solar AC / DC microgrid of the present invention further includes a gas buffer module. The gas buffer module includes a carbon dioxide storage tank and / or a syngas storage tank. The carbon dioxide storage tank is located between the carbon dioxide capture unit and the carbon dioxide electroreduction unit, and is used to store carbon dioxide. The syngas storage tank is located between the carbon dioxide electroreduction unit and the Fischer-Tropsch synthesis unit, and is used to store syngas composed of carbon monoxide and hydrogen. When the output power of the photovoltaic power generation unit is high, the gas production of the carbon dioxide capture unit is large, and the gas production of the carbon dioxide electroreduction unit is large, excess carbon dioxide enters the carbon dioxide storage tank, and excess syngas enters the syngas storage tank. When photovoltaic power is low, the gas is released from the carbon dioxide storage tank and / or the syngas storage tank to maintain the continuous and stable operation of the downstream Fischer-Tropsch synthesis unit and the hydrodistillation unit.

[0074] In one embodiment of the present invention, the energy dispatch module performs multi-level coordinated control based on the electrical status of the DC bus and / or AC bus (such as the voltage and current values ​​of the DC bus, the voltage amplitude and frequency, active power and reactive power of the AC bus), the load requirements of each process unit, the electrical energy storage capacity of the chemical energy storage module, and / or the gas storage capacity of the gas buffer module. This ensures that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range, thereby maintaining the continuous and stable operation of the sustainable aviation fuel production module under fluctuations in wind and solar power output. The energy dispatch module includes a primary control unit, a secondary coordination control unit, and a tertiary optimization control unit. See [link to relevant documentation]. Figure 4 The primary control unit includes an embedded controller (DSP / FPGA / PLC) that, based on DC bus electrical signals, DC load signals, AC bus electrical signals, and / or AC load signals, performs voltage-current dual closed-loop control of the DC bus and / or AC bus within millisecond cycles. This includes autonomous power distribution control based on droop curves, virtual impedance control, and current limiting or disconnection protection when the transient load of the DC or AC load exceeds the limit. The secondary coordination control unit, within second cycles, regulates the power flow between the AC and DC buses by controlling the power flow direction and magnitude of the bidirectional converter, maintaining AC bus frequency stability and / or DC bus voltage stability. It also uses a hybrid model based on reinforcement learning and fuzzy control to predict the operating load and photovoltaic fluctuations of each process unit in the next shorter time period (0.1-10s), setting power reference values ​​for the bidirectional DC / DC converter, DC / DC boost converter, DC / DC buck converter, and AC / DC converter (i.e., rotor-side converter). Based on historical and real-time data, the three-stage optimization control unit uses a time series model (LSTM / XGBoost) to predict the wind and solar power output for future periods (e.g., 5 minutes to 24 hours) within a minute to hour period. Based on the prediction results, with the goal of minimizing the actual operating load fluctuations of the Fischer-Tropsch synthesis unit and the hydrodistillation unit within a set range and minimizing power curtailment, it generates a preset power transmission plan for the bidirectional converter, a charging and discharging plan for the chemical energy storage module, a gas charging and discharging plan for the gas buffer module, and / or a power plan for the DC load.

[0075] Accordingly, the sustainable aviation fuel production system based on wind-solar AC / DC microgrids can be configured to operate in one of the following three modes:

[0076] Mode 1: Primarily relies on chemical energy storage modules for power buffering, while gas buffer modules only provide minimal material buffering;

[0077] Mode 2: It mainly relies on the gas buffer module for material buffering, and the chemical energy storage module is only used to ensure a stable power supply to the electrolysis hydrogen production unit.

[0078] Mode 3: A hybrid buffering strategy combining chemical energy storage modules and gas buffer modules is adopted to proportionally distribute fluctuating AC and DC power to both electrical storage and material storage paths.

[0079] This invention also proposes a sustainable aviation fuel production method based on a wind-solar AC / DC microgrid. The method is applied to the sustainable aviation fuel production system based on a wind-solar AC / DC microgrid as described above, and includes the following steps:

[0080] Step S1: Use wind power generation components to capture wind energy and generate alternating current (AC); use photovoltaic power generation components to capture solar energy and generate direct current (DC).

[0081] Step S2: Connect the AC power generated by wind power generation to the AC bus and the DC power generated by photovoltaic power generation to the DC bus.

[0082] Step S3: Connect the carbon dioxide electroreduction unit and the hydrogen electrolysis unit in the sustainable aviation fuel preparation module as DC loads to the DC bus, and connect the motor drive equipment (such as compressors, circulating pumps, fans) and / or heating equipment (electric steam generators, such as resistance or electrode electric steam boilers) in the carbon dioxide capture unit, Fischer-Tropsch synthesis unit and hydrodistillation unit in the sustainable aviation fuel preparation module as AC loads to the AC bus.

[0083] Step S4: Based on the electrical status of the DC bus and AC bus and / or the load requirements of each process unit in the sustainable aviation fuel preparation module, the energy dispatch module controls the power flow direction and magnitude of the bidirectional converter to adjust the power flow between the AC bus and the DC bus, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within the set range.

[0084] Step S4 of one embodiment of the present invention specifically includes:

[0085] Within millisecond cycles, the embedded controller (DSP / FPGA / PLC) performs voltage-current dual closed-loop control of the DC bus and / or AC bus, autonomous power distribution control based on droop curves, virtual impedance control, and current limiting or disconnection protection when the transient load of the DC load or AC load exceeds the limit, based on the DC bus electrical signal, DC load signal, AC bus electrical signal and / or AC load signal.

[0086] Within a second-level cycle, the power flow between the AC bus and the DC bus is adjusted by controlling the power flow direction and magnitude of the bidirectional converter, maintaining the stability of the AC bus frequency and / or the DC bus voltage. Furthermore, a hybrid model based on reinforcement learning and fuzzy control is used to predict the operating load and photovoltaic fluctuations of each process unit in the next shorter period (0.1-10s), and to adjust the set power reference values ​​of the bidirectional DC / DC converter, DC / DC boost converter, DC / DC buck converter, AC / DC converter (i.e., rotor-side converter), etc.

[0087] Within a minute or hourly timeframe, based on historical and real-time data, a time series model (LSTM / XGBoost) is used to predict wind and solar power output for future periods (e.g., 5 minutes to 24 hours). Based on the prediction results, with the goal of minimizing power curtailment and ensuring that the actual operating loads of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuate within a set range, a preset power transmission plan for the bidirectional converter, a charging and discharging plan for the chemical energy storage module, a gas charging and discharging plan for the gas buffer module, and / or a power plan for the DC load are generated.

[0088] The sustainable aviation fuel production system based on a wind-solar AC / DC microgrid of the present invention can intelligently switch between "daytime mode," "nighttime mode," "wind-solar resonance mode," and "off-peak mode" according to the wind and solar power output to adapt to all-weather energy changes. Specifically:

[0089] When photovoltaic output is dominant and wind power output is insufficient, switch to daytime mode: drive the electrolysis hydrogen production unit and carbon dioxide electroreduction unit through DC bus, and convert DC power into AC power through rotor-side converter to smooth the AC output of wind power generation components, and supply surplus power to AC bus through bidirectional converter, and / or store it in chemical energy storage module.

[0090] When wind power output is dominant and photovoltaic output is insufficient, switch to night mode: drive carbon dioxide capture unit, Fischer-Tropsch synthesis unit and hydrodistillation unit through AC bus, and supply AC power to DC bus through rotor-side converter (RSC, as AC / DC rectifier) ​​and / or bidirectional converter, discharge to compensate DC bus through chemical energy storage module, and / or release stored carbon dioxide and / or synthesis gas through gas buffer module.

[0091] When both wind and solar power output are sufficient, switch to wind-solar resonance mode: increase the operating load of each process unit in the sustainable aviation fuel preparation module, store carbon dioxide and / or syngas through the gas buffer module, and / or store surplus electrical energy through the chemical energy storage module;

[0092] When both wind and solar power output are insufficient, the system switches to off-peak mode: the stored carbon dioxide and / or synthesis gas are released through the chemical energy storage module and / or the gas buffer module, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit can continue to operate within the set range.

[0093] When the wind speed is low and the turbine speed is lower than the synchronous speed, the doubly-fed induction generator (DFIG) operates in a sub-synchronous state. Under this condition, the stator winding is directly connected to the AC bus, and the frequency and phase of its output AC current are forcibly locked by the AC bus, independent of the mechanical speed. To maintain a stable electromagnetic coupling relationship, the rotor-side converter needs to inject a controlled current corresponding to the slip between the rotor speed and the synchronous speed into the rotor via the DC bus, thereby adjusting the rotational speed of the rotor magnetic field so that the air gap composite magnetic field still rotates at the synchronous speed.

[0094] When wind speed is high and the wind turbine's mechanical speed exceeds the synchronous speed, the doubly-fed induction generator (DFIG) operates in a super-synchronous state. Under this condition, the stator windings are also directly connected to the AC bus, and the frequency and phase of the output AC power are still forcibly locked by the AC bus, independent of the mechanical speed. Because the rotor speed exceeds the synchronous speed, the system exhibits negative slip characteristics. To maintain stable electromagnetic coupling, the rotor-side converter needs to absorb a controlled current corresponding to the slip frequency from the rotor circuit, based on the slip between the rotor speed and the synchronous speed, causing the rotor magnetic field to rotate in the opposite direction relative to the rotor, thus ensuring that the air gap composite magnetic field still rotates at the synchronous speed. During this process, in addition to the mechanical input power being directly fed into the AC bus via the stator, excess slip power is rectified to the DC bus through the rotor-side converter. The sustainable aviation fuel production system based on a wind-solar AC / DC microgrid of this invention will be described in detail below using specific data and embodiments.

[0095] The overall concept of the sustainable aviation fuel production system based on a wind-solar AC / DC microgrid of this invention is as follows: wind power and photovoltaic power generation are respectively connected to the AC bus and DC bus to achieve energy complementarity; a bidirectional converter achieves real-time balance of AC-DC energy flow; modules such as DAC, CO2 reduction, water electrolysis for hydrogen production, and Fischer-Tropsch (FT) synthesis are assigned to different buses according to load characteristics to reduce AC / DC conversion losses. Chemical energy storage modules and gas buffer modules participate in energy dispatch to achieve continuous operation under green electricity fluctuations.

[0096] The preferred wind power generation components are doubly-fed induction generators (DFIGs), whose structure is as follows: Figure 2As shown, the stator side of the DFIG is directly connected to the AC bus, outputting stable power frequency AC (e.g., 50 Hz, rated voltage). The rotor side of the DFIG is connected to the DC bus through a rotor-side converter. Adjusting the electromagnetic torque and excitation current achieves bidirectional active power regulation of ±25% of rated power. This RSC is essentially a bidirectional AC / DC converter, its function being to convert the slip frequency AC power on the rotor side into DC power for feeding into the DC bus, or vice versa. This connection method makes the rotor path of the DFIG a dynamic electromagnetic buffer, capable of absorbing wind speed fluctuations. The power after rectification by the RSC changes with the positive or negative wind speed, forming a dynamic buffer on the DC side, thereby smoothing the AC output power on the stator side.

[0097] The photovoltaic (PV) power generation module calculates its maximum power point (MPPT) using an MPPT controller and connects to the DC bus via a DC / DC boost converter. Its control structure is as follows: Figure 3 As shown, the DC power output from the photovoltaic (PV) modules is first calculated and tracked in real time by the MPPT controller, which then outputs control commands to the DC / DC boost converter. The MPPT control adjusts the operating voltage of the PV modules in real time to ensure they always operate at the instantaneous maximum power point, maximizing DC output power under dynamic changes in sunlight and temperature. The DC / DC boost converter adjusts the duty cycle according to the MPPT output commands, locking the PV voltage at the optimal voltage corresponding to the MPPT. During peak sunlight periods, the PV DC power prioritizes providing main power input to the electrolyzer and CO2 reduction reactor in the hydrogen electrolysis unit. When PV power generation raises the DC bus voltage, energy is automatically distributed to the chemical energy storage module for charging via the bidirectional DC / DC converter. When the energy storage is fully charged or the load is low, excess energy can be further fed back to the AC bus side via the bidirectional converter to power AC loads such as DAC wind turbines and circulating pumps, achieving wind-solar complementarity and efficient DC-side energy dispatch.

[0098] Based on the above structure, the AC bus power supply path, DC bus power supply path, and power mutual assistance path can be obtained.

[0099] The AC bus power supply path is as follows: after capturing wind energy, the wind turbine drives a doubly-fed induction generator (DFIG) via a gearbox. The stator side of the DFIG is directly connected to the AC bus, outputting constant-frequency and constant-voltage AC power, providing the AC bus with stable AC power (50Hz, rated voltage) as the basic power supply bus for AC loads. AC loads mainly come from motor-driven equipment (such as fans, compressors, and circulating pumps, typically driven by VFDs) and electric heating equipment (such as electric steam generators) in the SAF preparation module. Electric heating equipment, such as resistance or electrode electric steam boilers, is directly connected to the AC bus; electrical energy is converted into heat energy via resistance / electrode to generate process steam (for DAC desorption or FT heating). Various motor loads draw power from the AC bus via contactors or VFDs; electrical energy is converted into mechanical energy via electromagnetic conversion, mainly used in DAC adsorption fans, CO2 / syngas compressors, circulating pumps, etc.

[0100] The DC bus power supply path is as follows: The photovoltaic (PV) modules first extract their maximum DC output power via an MPPT (Maximum Power Point Tracking) controller. Then, the voltage is adjusted to the DC bus voltage level by a DC / DC boost module and directly connected to the DC bus, achieving complete DC coupling. The PV DC side does not pass through an inverter. The MPPT ensures that the PV remains stable at its maximum power point under rapid irradiance fluctuations, improving energy capture efficiency and guaranteeing high-quality DC power to the electrolyzer and energy storage modules under full-day irradiance fluctuations. The DC power from the DC bus enters the electrolyzer via a dedicated DC / DC buck converter, achieving optimal current density scheduling. DC-side coupling avoids AC / DC conversion losses, allowing electrical energy to be directly converted into chemical energy (H2 or CO / H2), suitable for PEM and eCO2RR reactors.

[0101] The power balance path is as follows: When the AC side output is excessive (high wind speed, weak photovoltaic power), part of the power can be rectified to the DC bus through a bidirectional AC / DC converter to provide DC power to the electrolyzer and eCO2RR. When the AC side power is insufficient, it operates in reverse to invert the DC bus energy to compensate for the AC side load.

[0102] Chemical energy storage modules (such as lithium batteries and flow batteries) are directly connected to the DC bus via a bidirectional DC / DC converter, achieving DC coupling on the energy storage side. When there is surplus photovoltaic power, the energy storage is charged by the DC / DC converter to absorb the remaining DC power; when there is a downturn in wind and solar power, the energy storage is discharged by the DC / DC converter to maintain the stability of the DC bus.

[0103] The CO2 / CO / H2 syngas storage tank serves as an hourly energy buffer. When the PV+ energy storage input power is high and the eCO2RR gas production is large, the excess syngas enters the storage tank. When renewable electricity is low, the storage tank releases syngas to maintain the continuous and stable operation of the FT synthesis section.

[0104] The Sustainable Aviation Fuel (SAF) preparation module comprises five sequentially connected process units:

[0105] (1) Carbon Dioxide Capture Unit (DAC): This unit captures carbon dioxide from the air using either liquid absorption (e.g., organic amine solution) or solid adsorption. When using liquid absorption, air is fed into the absorption tower by a fan, where it reacts counter-currently with the absorbent to generate a rich solution. This solution is then pumped to the regeneration tower for desorption. The desorption temperature is approximately 80-110 degrees Celsius, and the produced CO2 purity is >99%. Absorbent types include alkaline solutions such as NaOH, KOH, and Ca(OH)2 hydroxide solutions, which chemically absorb carbon dioxide to generate carbonates (Na2C). K2C This includes solutions containing organic amines, such as Monoethanolamine (MEA), Diethanolamine (DEA), Methyldiethanolamine (MDEA), and Piperazine (PZ). The driving fans, solution circulation pumps, and other motorized equipment are AC loads connected to the AC bus. The heat energy required for the regeneration tower can be provided by an electric steam generator and / or a heat pump (AC load), or preferably by utilizing the waste heat generated by the downstream Fischer-Tropsch synthesis unit to achieve energy integration. In the solid adsorption method, air is sent into the adsorption bed collector by a fan to react with the adsorbent. After adsorption, the air is evacuated to 50-90 kPa and then heated by steam to the desorption temperature of 80-120 degrees Celsius for desorption. Adsorbents include amine-functionalized adsorbents, MOFs, and porous inorganic materials such as zeolites. In the solid adsorption method, the driving fans and other motorized equipment are AC loads connected to the AC bus; the heat energy required for the steam generator is provided by the AC load, or preferably by utilizing the waste heat generated by the downstream Fischer-Tropsch synthesis unit to achieve energy integration.

[0106] (2) Carbon dioxide electroreduction unit (eC RR): eC The RR unit co-electrolyzes carbon dioxide and water into carbon monoxide and hydrogen, which together produce syngas. The unit is powered by a DC bus and utilizes an electrochemical reaction at atmospheric pressure and 40-60 degrees Celsius to reduce CO2 to CO at the cathode, while simultaneously electrolyzing water to generate H2. This achieves co-electrolysis of CO / H2 syngas, with oxygen produced at the anode. The cathode (CO2 reduction and hydrogen evolution electrode) includes silver (Ag)-based and copper (Cu)-based catalysts. The anode (oxygen evolution electrode) includes IrO2 and RuO2 catalysts supported on a titanium mesh or nickel foam. The electrolyte includes acidic electrolytes such as K2SO4, Na2SO4, KHCO3, and NaHCO3, and the membrane is a Nafion membrane commonly used in PEMs. This unit draws power directly from the DC bus via a DC / DC step-down converter, providing rapid load regulation capabilities on the order of milliseconds to seconds.

[0107] (3) Electrolysis Hydrogen Production Unit (PEM): The PEM electrolyzer electrolyzes water into hydrogen, which is then supplied to the Fischer-Tropsch synthesis unit or the hydrodistillation unit. The proton exchange membrane is Nafion; the anode catalyst includes IrO2 and RuO2; and the cathode is Pt / C or Pt–Ru / C. Power is supplied via a DC bus.

[0108] (4) Fischer-Tropsch synthesis unit and hydrodistillation unit: Under the action of a catalyst, the synthesis gas (H2:CO=2:1) ​​is catalytically reacted with an iron-based or cobalt-based catalyst at 200-270 degrees Celsius to produce long-chain hydrocarbon oils and waxes, which are then subjected to hydrocracking, isomerization, and distillation to produce SAF products that meet the ASTM D7566 standard. The compressors, feed pumps, reboilers, and other motor equipment in these two units are AC loads and connected to the AC bus. Their loads need to be kept highly stable (fluctuations are recommended to be controlled between 80%-100% of the rated load) to ensure reaction efficiency, catalyst life, and product quality.

[0109] Regarding the energy dispatch module, a multi-level AI intelligent control system is adopted, consisting of three layers: primary control, secondary coordination control, and tertiary global optimization control, to achieve full-cycle dynamic management of wind and solar power generation, AC / DC buses, energy storage systems, and chemical loads.

[0110] The primary control (Local Control) is implemented by an embedded controller (DSP / FPGA / PLC) deployed inside each power electronic converter (such as photovoltaic DC / DC, battery DC / DC, bidirectional converter, RSC). The response time is in the millisecond range and it relies on local sensors. It is responsible for the lowest level, fastest, and communication-independent local stability control. The typical sampling period is 0.1–1ms. Even if communication is interrupted, the system can maintain stability and is the basic safety layer of the entire system. The core functions include: (1) Voltage, current and bus (AC / DC) voltage regulation control: DC / DC, AC / DC and DC / AC converters adopt voltage-current PI control (voltage / current dual-loop control) or nonlinear boundary control; the AC side adopts a voltage outer loop + current inner loop structure to maintain a stable frequency and rated voltage. (2) Droop Control for Automatic Power Distribution: The DC bus adopts V-I droop control (V-P or V-Idroop), which allows multiple power sources to automatically share power without communication. For example, when the current increases and the voltage drops slightly, other power sources will actively take on part of the load. The AC bus achieves stable grid connection of fans and inverters through P-f and Q-V droop control. (3) Virtual Impedance and Active Damping: Improve the stability of the DC bus and suppress the negative resistance phenomenon caused by CPL (constant power load); improve the impedance shape of the bus and avoid high-frequency oscillation. (4) Fast Protection of Terminal Loads: Transient large loads such as electrolytic cells, electric steam boilers, and motors are directly limited / cut off by primary control, and the response time can be as low as sub-millisecond.

[0111] Secondary Control has a response time of seconds, enabling dynamic scheduling at the 0.1–10 second level. Through local communication or point-to-point communication, power coordination, bus restoration, and energy storage management of the AC / DC domains are achieved, realizing cross-module collaboration, so that the AC and DC regions can restore voltage and power balance within a few seconds, reducing the impact of wind and solar disturbances on chemical loads. Specifically, a hybrid strategy of droop compensation + AI collaborative scheduling is adopted, the main functions of which are: (1) Bus voltage / frequency restoration: compensate for the bus offset caused by the first droop, so that the AC frequency is restored to a stable frequency and the DC bus is restored to its rated voltage. (2) Cross-module power allocation (coordination of PV-energy storage-electrolysis-DFIG): according to the real-time power balance, quickly schedule the power transmission direction and magnitude of the bidirectional converter, and instruct the charging and discharging of the energy storage unit. For example, when wind and solar power are strong, control the priority of energy storage charging and DAC regeneration to reduce power curtailment; when the voltage drops or the SOC is low: automatically trigger the electrolytic cell to reduce load, and the energy storage discharge supports the DC bus. (3) Short-term dynamic scheduling (0.1–10s): Using a hybrid model based on reinforcement learning and fuzzy control to predict the load and photovoltaic fluctuations in the next period, setting power reference values ​​for DC / DC and AC / DC converters to achieve rapid coordination. (4) Multi-terminal consistency control: Distributing current equally among energy storage and inverter groups to ensure that each power node shares the global state without relying on the central controller.

[0112] Tertiary Control (EMS): With a response time ranging from minutes to hours, it is responsible for global optimization. Performed by the Energy Management System (EMS), it is responsible for predicting, planning, and optimizing the entire PtL-SAF system. Time series models (such as LSTM and XGBoost) are used to predict wind and solar power output and the load of each process unit for the next 5 minutes to 24 hours, combining DAC, eCO2RR, PEM, FT, and energy storage demand to form load curves. Based on the prediction results, with the goals of maximizing green electricity utilization, minimizing power curtailment, and ensuring the stability of downstream continuous processes, optimal scheduling plans are generated and issued on a rolling basis, including charging and discharging plans for energy storage units, feeding / discharging plans for gas buffer units, and plans for electrolyzers / eCO2RR. The power curve plan of RR, as well as the preset power transmission plan of the bidirectional converter, ensure that the temperature and pressure of the PtL chemical process are not disturbed by wind and solar fluctuations.

[0113] The above system can implement four main operating modes:

[0114] (1) Daytime mode (photovoltaic main supply): Photovoltaic power is supplied through DC bus, DC assists DFIG to output stable AC wind power, and energy storage is charged at the same time;

[0115] (2) Night mode (mainly supplied by wind power): Wind power is output through DFIG and sent to DC bus for maintenance and operation through RSC regulation, with energy storage discharge compensation;

[0116] (3) Wind and solar resonance mode (peak period): wind and solar power output are high at the same time, the DC bus power is sufficient, and the output is driven by bidirectional inverter to drive DAC wind turbine and compressor;

[0117] (4) Off-peak mode: Energy storage and gas storage work together to release energy, maintain the stability of FT and hydrogenation reaction, ensure their safe operation, and get through the off-peak period.

[0118] Table 1 shows the energy consumption proportions and main power consumption forms of each unit in the sustainable aviation fuel preparation module of this invention. The energy consumption of the DAC module is divided into two parts: the moving equipment in the process unit and the steam heat during regeneration, with heat energy accounting for a larger proportion. CO2RR is the largest energy consumption component, requiring approximately 60% DC power. The energy consumption of the FT equipment mainly comes from heating, compression, and other moving equipment. Simultaneously, the exothermic reaction of FT provides a large amount of heat, which can supply the steam to the DAC module; therefore, the energy consumption proportion of FT (steam package heat extraction) is negative. The energy consumption required by the hydrogenation unit includes the electricity consumption for water electrolysis, compression and heating of the hydrogenation unit, and distillation of SAF oil. The energy consumption of each unit can be further divided into DC and AC requirements: the electrolyzer requires DC, the motor / compressor requires AC after frequency conversion, and the electric heating device requires AC. When all AC loads in the system (including motor drive equipment and electric heating equipment) are powered directly or via frequency converter from the AC bus, the total demand ratio of AC to DC for the entire preparation module is approximately 0.367:0.633.

[0119] Table 1. Energy Consumption Ratio and Main Power Consumption Methods of Each Process Unit in the SAF Preparation Module

[0120]

[0121] Based on the aforementioned load requirements, the wind-solar ratio is designed. The following example uses a 100MW wind-solar installed capacity with a wind-solar ratio of 2:8. This example uses the average value from Northwest China. In this configuration, solar power is connected to the DC bus, and wind power utilizes DFIG turbines, with the stator connected to the AC bus and the rotor connected to the DC bus. The electrical chain and efficiency of the wind-solar power generation connection to the bus are shown in Table 2 below.

[0122] Table 2 Electrical Chain and Efficiency of Wind and Solar Power Generation Connected Bus

[0123]

[0124] Northwest wind and solar power daily output coefficients are as follows Figure 5As shown in Table 3, the hourly wind and solar power generation and corresponding bus power data for the day are as follows, including the actual power output of the AC and DC buses. The average daily AC to DC bus power ratio is 0.358:0.642, which is close to the AC / DC ratio of each module in the production line. This output coefficient can meet the AC and DC demands of the entire production line. If the daily output is higher than in this embodiment (solar power increase or wind power decrease), excess DC power can be stored in energy storage batteries, or a small amount of power can be wasted. If the daily output is higher than in this embodiment (wind power increase or solar power decrease), a small amount of AC power can be wasted, or possible mechanical energy storage (flywheel, compressed air, compressed CO2, etc.) can be used.

[0125] Table 3. Daily Hourly Wind and Solar Power Generation and Bus Power Data

[0126]

[0127] Based on the power supply efficiency of the equipment in each process unit of the sustainable aviation fuel production module as shown in Table 4, combined with the AC bus power, the average daily SAF production is 2710 kta. Further, the hourly SAF production and power consumption data for each process unit are obtained, as shown in Table 5, including the actual power consumption of the FT and hydrogenation sections (DC / AC power consumption in parentheses in Table 5 refers to the actual power required from each bus). The load fluctuations of FT and hydrogenation are between 80% and 100%, ensuring that the equipment and catalyst are not affected by fluctuations, thus protecting safety and product composition. Finally, the remaining DC bus power, excluding PEM hydrogen production, is used for co-electrolysis reduction. If it is negative, it indicates that energy storage is needed to supply PEM during that period.

[0128] Table 4. Electrical Chains and Efficiency of Each Process Unit in the Sustainable Aviation Fuel Preparation Module

[0129]

[0130] Table 5. Daily hourly SAF output and power consumption data for each process unit.

[0131]

[0132] Based on the above data, it can be seen that CO2RR operation requires the assistance of storage or energy storage. Energy storage means smoothing out the peaks and valleys of the remaining DC power fluctuation curve; storage refers to producing syngas according to the fluctuation curve, while simultaneously storing enough CO2 and syngas to ensure stable operation of upstream and downstream processes. Energy storage involves conversion losses between the grid and the battery. In this embodiment, the charge and discharge efficiency of the energy storage battery is shown in Table 6. Although energy storage batteries are relatively expensive, energy storage is a necessary investment to address potential safety issues under abnormal weather conditions.

[0133] Table 6. Energy Storage Battery Charge and Discharge Efficiency

[0134]

[0135] Spatiotemporal decoupling can be achieved through three configuration methods using energy storage and / or gas storage, and the volatility of DC-side photovoltaic power generation can be addressed by leveraging the flexibility of the electrolyzers used by DC-side users.

[0136] Configuration 1: Buffer mode relying entirely on energy storage without a gas buffer tank: In this mode, the system primarily relies on large-capacity electrochemical energy storage to smooth out all power fluctuations, with the gas buffer maintaining only the minimum necessary capacity. (C) Table 7 shows the RR operation and energy storage charge / discharge data. In this typical daily operation, to maintain stable (with minimal fluctuations) loads on the downstream FT and hydrogen refueling units, the required energy storage capacity is approximately 220-250 MWh. When wind and solar power output is excessive, the electrical energy is stored in the battery (charge / discharge values ​​are positive in the table); when output is insufficient, the battery discharges to compensate (charge / discharge values ​​are negative in the table). This mode can maximize the absolute stability of the chemical side, but it requires significant investment in energy storage.

[0137] Table 7 C under the mode of complete reliance on energy storage RR operation and energy storage charge / discharge data sheet

[0138]

[0139] Table 8 shows the operating data and output of each process unit in the SAF module under this configuration. As can be seen from Table 8, the system can operate under stable load under this energy storage scale.

[0140] Table 8. Operating data and SAF production data of each process unit under the fully energy storage-dependent mode.

[0141]

[0142] Configuration Option 2: Buffer Mode Primarily Relying on Gas Storage: In this mode, the system primarily relies on syngas and carbon dioxide storage tanks for material buffering. Energy storage is only used to ensure the stability of PEM electrolysis hydrogen production and does not participate in the energy supply or storage of other processes. Electricity consumption is evenly distributed across sufficient hours each day to ensure a balance between electricity consumption and storage. Energy storage and CO2RR operation data for this mode are shown in Table 9. Based on the data in Table 9, the required syngas storage tank capacity, as shown in Table 10, is approximately 50,000-60,000 Nm³, and the required carbon dioxide storage tank capacity, as shown in Table 11, is approximately 25,000-30,000 Nm³. When wind and solar power output is high, the eCO2RR unit operates at high load, and excess syngas produced is stored in the tanks; when output is low, the eCO2RR load is reduced, and syngas is released from the tanks to ensure continuous operation of the FT unit. This mode significantly reduces energy storage investment but increases tank investment and material management complexity.

[0143] Table 9. Energy Storage and CO2RR Operation Data under Buffer Mode Primarily Reliant on Gas Storage

[0144]

[0145] Table 10 Syngas Operation Data under Buffer Mode Primarily Reliant on Gas Storage

[0146]

[0147] Table 11. Carbon dioxide operation data under buffer mode mainly relying on gas storage

[0148]

[0149] Configuration Option 3: Hybrid Buffer Mode of Energy Storage and Gas Storage: This mode is a compromise and optimization of the previous two. For example, it is set that wind and solar power fluctuations are handled equally by energy storage and gas storage. That is, when there is excess power generation, 50% of the excess power generation beyond maintaining downstream stability is sent to the energy storage device, and the remaining 50% is stored in the storage tank after production. When there is insufficient power generation, 50% of the syngas required to maintain downstream stability is provided by the storage tank, and the remaining 50% is produced by energy storage power generation. The CO2RR and energy storage operation data under this mode are shown in Table 12. As shown in Table 12, under this configuration, the required energy storage capacity is reduced to 110-130 MWh, and the syngas storage tank capacity is reduced to 25,000-30,000 Nm³. As shown in Table 13, the carbon dioxide storage needs to be 12,000-15,000 Nm³. Moreover, the syngas storage capacity can be increased on the same day, and the design of the syngas storage tank has multi-day feasibility.

[0150] The system flexibly allocates fluctuating energy to two paths—electrical storage and chemical storage—based on real-time conditions, achieving an optimal balance between investment costs, operational efficiency, and system reliability. As shown in the last row of Tables 10 and 11, through a reasonable scheduling strategy, the energy storage capacity and material storage can achieve a dynamic balance over multiple days of operation, ensuring long-term sustainability.

[0151] Table 12 CO2RR and Energy Storage Operation Data under Hybrid Buffer Mode of Energy Storage and Gas Storage

[0152]

[0153] Table 13 CO2 Operation Data under the Hybrid Buffer Mode of Energy Storage and Gas Storage

[0154]

[0155] As shown in Tables 12 and 13, under the hybrid buffer mode of energy storage and gas storage, the stored electricity and synthesizer storage both increase after the end of the day, while the carbon dioxide storage decreases. In this situation, the strategy needs to be adjusted promptly. On the next day, electricity consumption should be shifted towards the DAC segment to achieve the goal of producing and storing more CO2, reducing the amount of reduced syngas, and using the excess syngas for the stable operation of the downstream FT, thus promptly absorbing the excess syngas. This ensures that the overall system's storage reaches a balance over multiple days, demonstrating sustainability.

[0156] All three configuration methods described above can achieve the goal of absorbing green electricity to supply the PtL route and ensuring the stable operation of the complete SAF process route, while minimizing the amount of electricity wasted.

[0157] It should be noted that, in this application, unless otherwise explicitly specified and limited, terms such as "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0158] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0159] The constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in size, structure, shape, and proportions, as well as parameter values, installation arrangements, use of materials, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the elements may be inverted or otherwise changed, and the nature or number or position of discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of this invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Various corresponding modifications and variations can be made by those skilled in the art according to this invention without departing from the spirit and essence of the invention, but such corresponding modifications and variations should fall within the protection scope of this invention.

Claims

1. A sustainable aviation fuel production system based on wind-solar AC / DC microgrids, characterized in that, include: Wind power generation components convert wind energy into constant voltage and constant frequency alternating current and direct current; The AC busbar connects to the wind turbine generator components to obtain AC power. Photovoltaic power generation modules convert sunlight into direct current. The DC bus connects the photovoltaic power generation modules and the wind power generation modules to obtain DC power. A bidirectional converter is connected between the AC bus and the DC bus to perform bidirectional conversion between AC and DC power. The sustainable aviation fuel production module converts carbon dioxide into aviation fuel. It includes five process units: a carbon dioxide capture unit for capturing carbon dioxide from the air, a carbon dioxide electroreduction unit for electrolyzing carbon dioxide and water to generate syngas from carbon monoxide and hydrogen, an electrolysis hydrogen production unit for electrolyzing water to generate hydrogen, a Fischer-Tropsch synthesis unit for converting syngas into oil and wax, and a hydrodistillation unit for converting oil and wax into aviation fuel through catalytic hydrogenation and distillation. The carbon dioxide electroreduction unit and the electrolysis hydrogen production unit are connected to the DC bus as DC loads, while the motor drive equipment and / or heating equipment in the carbon dioxide capture unit, the Fischer-Tropsch synthesis unit, and the hydrodistillation unit are connected to the AC bus as AC loads. The energy dispatch module, based on the electrical status of the DC bus and AC bus and / or the load requirements of each process unit, regulates the power flow between the AC bus and DC bus through a bidirectional converter; The energy scheduling module performs multi-level coordinated control to keep the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit within a set range, including a primary control unit, a secondary coordinated control unit, and a tertiary optimization control unit. The primary control unit includes an embedded controller that performs voltage-current dual closed-loop control of the DC bus and / or AC bus, autonomous power distribution control based on droop curves, virtual impedance control, and current limiting or disconnection protection when the transient load of the DC load or AC load exceeds the limit, based on the DC bus electrical signal, DC load signal, AC bus electrical signal and / or AC load signal. The secondary coordination control unit regulates the power flow between the AC bus and the DC bus by controlling the bidirectional converter, thereby maintaining the stability of the AC bus frequency and / or the DC bus voltage. The three-stage optimization control unit uses historical and real-time data and time series models to predict wind and solar power output for future periods. Based on the prediction results, and with the goal of minimizing power curtailment while keeping the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit within a set range, it generates a preset power transmission plan for the bidirectional converter, a charging and discharging plan for the chemical energy storage module, a charging and discharging plan for the gas buffer module, and / or a power plan for the DC load.

2. The sustainable aviation fuel production system based on wind-solar AC / DC microgrids according to claim 1, characterized in that, The wind power generation components include a doubly fed induction generator; The stator side of the doubly-fed induction generator is directly connected to the AC bus, and it outputs constant voltage and constant frequency AC power. The rotor side of the doubly fed induction generator is connected to the DC bus via a rotor-side converter, which converts AC power into DC power.

3. The sustainable aviation fuel production system based on wind-solar AC / DC microgrids according to claim 1, characterized in that, It also includes a maximum power point tracking controller (MPPT) and a DC / DC boost converter; The maximum power point tracking controller (MPPT) is connected to the photovoltaic (PV) power generation module, calculates the maximum power point of the PV power generation module, and outputs control commands. The DC / DC boost converter maintains the operating point of the photovoltaic power generation module at the maximum power point according to the instructions output by the maximum power point tracking controller (MPPT), and boosts the output voltage of the photovoltaic power generation module to a voltage level that matches the DC bus.

4. The sustainable aviation fuel production system based on wind-solar AC / DC microgrids according to claim 1, characterized in that, The electrolyzers of the carbon dioxide electroreduction unit and the electrolytic hydrogen production unit draw power from the DC bus via a DC / DC step-down converter; The motor-driven equipment includes at least one of a compressor, a fan, and a circulating pump, and draws power from the AC bus via a frequency converter and a transformer. The heating equipment includes at least one of an electric steam generator and a heat pump, and draws power from the AC bus via a transformer.

5. The sustainable aviation fuel production system based on wind-solar AC / DC microgrids according to claim 1, characterized in that, It also includes a chemical energy storage module, which is connected to the DC bus via a bidirectional DC / DC converter to store excess electrical energy from the DC bus or discharge it when needed to maintain the voltage stability of the DC bus.

6. The sustainable aviation fuel production system based on wind-solar AC / DC microgrids according to claim 5, characterized in that, It also includes a gas buffer module, which includes a carbon dioxide storage tank and / or a syngas storage tank; The carbon dioxide storage tank is located between the carbon dioxide capture unit and the carbon dioxide electroreduction unit and is used to store carbon dioxide. The syngas storage tank is located between the carbon dioxide electroreduction unit and the Fischer-Tropsch synthesis unit, and is used to store syngas composed of carbon monoxide and hydrogen.

7. A sustainable aviation fuel preparation method based on wind-solar AC / DC microgrids, characterized in that, The method, applied to the sustainable aviation fuel production system based on wind-solar AC / DC microgrids as described in any one of claims 1-6, includes the following steps: Wind energy is captured using wind power generation components to generate alternating current; Photovoltaic power generation modules capture solar energy to generate direct current. Connect the AC power generated by wind power generation to the AC bus, and connect the DC power generated by photovoltaic power generation to the DC bus. The carbon dioxide electroreduction unit and the electrolytic hydrogen production unit in the sustainable aviation fuel preparation module are connected to the DC bus as DC loads, and the motor drive equipment and / or heating equipment in the carbon dioxide capture unit, Fischer-Tropsch synthesis unit and hydrodistillation unit in the sustainable aviation fuel preparation module are connected to the AC bus as AC loads. The energy dispatch module controls the bidirectional converter to regulate the power flow between the AC bus and the DC bus based on the electrical status of the DC bus and the AC bus and / or the load demand of each process unit in the sustainable aviation fuel preparation module, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range.

8. The sustainable aviation fuel preparation method based on wind-solar AC / DC microgrids according to claim 7, characterized in that, The energy dispatch module controls the bidirectional converter to regulate the power flow between the AC and DC buses based on the electrical status of the DC and AC buses and / or the load requirements of each process unit in the sustainable aviation fuel preparation module. This ensures that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range. Specifically, this includes: Within a millisecond period, the embedded controller performs voltage-current dual closed-loop control of the DC bus and / or AC bus, autonomous power distribution control based on the droop curve, virtual impedance control, and current limiting or disconnection protection when the transient load of the DC load or AC load exceeds the limit, based on the DC bus electrical signal, DC load signal, AC bus electrical signal and / or AC load signal. Within a second-level cycle, the power flow between the AC bus and the DC bus is regulated by controlling the bidirectional converter to maintain the stability of the AC bus frequency and / or the DC bus voltage. Within a minute or hourly cycle, based on historical and real-time data, a time series model is used to predict the wind and solar power output for future periods. Based on the prediction results, with the goal of minimizing power curtailment and ensuring that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit fluctuates within a set range, a preset power transmission plan for the bidirectional converter, a charging and discharging plan for the chemical energy storage module, a charging and discharging plan for the gas buffer module, and / or a power plan for the DC load are generated.

9. The sustainable aviation fuel preparation method based on wind-solar AC / DC microgrids according to claim 7, characterized in that, When photovoltaic output is dominant and wind power output is insufficient, the electrolysis hydrogen production unit and carbon dioxide electroreduction unit are driven by DC bus, and the DC power is converted into AC power by rotor-side converter to smooth the AC output of wind power generation components. The surplus power is supplied to AC bus by bidirectional converter and / or stored in chemical energy storage module. When wind power output is dominant and photovoltaic output is insufficient, the carbon dioxide capture unit, Fischer-Tropsch synthesis unit and hydrodistillation unit are driven by the AC bus, and the AC power is supplied to the DC bus through the rotor-side converter and / or bidirectional converter. The DC bus is compensated by discharging through the chemical energy storage module, and / or the stored carbon dioxide and / or synthesis gas is released through the gas buffer module. When wind and solar power outputs are sufficient, increase the operating load of each process unit in the sustainable aviation fuel preparation module, and store carbon dioxide and / or syngas through the gas buffer module, and / or store surplus electrical energy through the chemical energy storage module. When wind and solar power output is insufficient, the stored carbon dioxide and / or synthesis gas are released through the chemical energy storage module and / or the gas buffer module, so that the actual operating load of the Fischer-Tropsch synthesis unit and the hydrodistillation unit can continue to operate within the set range.

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