Wind-solar complementary combined supply system integrated with Carnot cell and optimization method of wind-solar complementary combined supply system

Abstract

The invention discloses a wind-solar complementary combined supply system integrated with a Carnot cell and an optimization method thereof, and the system comprises a synthesis gas preparation unit which is used for converting solar energy into electric energy and heat energy at the same time, and then methanol decomposition is assisted through the heat energy, so that the solar energy is converted into chemical energy stored in synthesis gas; the wind power generation system is used for converting wind energy into electric energy; the solid oxide fuel cell power generation unit is connected with the synthesis gas preparation unit and is used for converting chemical energy in the synthesis gas into electric energy and heat energy; the waste heat utilization unit is connected with the solid oxide fuel cell power generation unit and used for recycling high-temperature flue gas waste heat generated by the solid oxide fuel cell power generation unit and converting high-temperature heat energy into electric energy, heat energy and cold energy through steam circulation and transcritical CO2 refrigeration circulation; and the Carnot battery energy storage unit is used for receiving redundant electric energy of each unit, converting the redundant electric energy into heat energy and converting the heat energy into electric energy, heat energy and cold energy when needed so as to adjust supply and demand balance of the system and realize multi-energy complementary output.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, specifically to a wind-solar hybrid power generation system integrating Carnot batteries and its optimization method. Background Technology

[0002] Distributed energy systems, centered on renewable energy sources, are considered a key technological direction for solving the energy dilemma due to their advantages of being close to users, flexible, efficient, low-carbon, and environmentally friendly. Among them, solar energy, with its significant advantages of unlimited reserves, wide distribution, safety, and zero pollution emissions, has become the clean energy source with the greatest development potential. Currently, distributed solar energy utilization mainly relies on two types of technologies: photovoltaic power generation uses the photovoltaic effect of semiconductor materials to directly convert light energy into electrical energy; solar thermal utilization converts solar energy into heat energy through heat collection equipment for heating or driving heat engines to generate electricity. However, existing photovoltaic and solar thermal utilization technologies both have significant inherent defects and bottlenecks, which seriously restrict their efficiency and stability.

[0004] On the other hand, distributed energy systems, as energy systems distributed on the user side that combine power generation, cooling, and heating, are affected by user loads. However, user loads are not fixed under the influence of external conditions. To meet the ever-changing load demands of users, distributed energy systems typically operate under variable operating conditions. This mismatch between the energy supply side and the energy consumption side will cause a sharp deterioration in the thermal performance, environmental performance, and economic performance of distributed energy systems. Summary of the Invention

[0005] The purpose of this invention is to provide a wind-solar hybrid power supply system with integrated Carnot batteries and its optimization method. It aims to improve the problems of low efficiency of photovoltaic and solar thermal technologies, high cost of energy storage due to the intermittency of solar energy, and supply and demand mismatch between the supply and demand sides of distributed energy supply systems, which leads to the deterioration of the system's thermal performance, environmental performance and economic performance. At the same time, it solves the problems of high curtailment rates of solar and wind power in renewable energy utilization, and the difficulty of continuously and stably supplying multiple loads of cooling, heating and electricity when wind and solar resources are poor.

[0006] The present invention is implemented as follows: According to one aspect of the present invention, a wind-solar hybrid power supply system integrating Carnot batteries is provided, comprising:

[0007] The syngas preparation unit is used to convert solar energy into electrical and thermal energy, and then use thermal energy to assist in the decomposition of methanol, thereby converting solar energy into chemical energy stored in syngas.

[0008] Wind power generation systems are used to convert wind energy into electrical energy;

[0009] The solid oxide fuel cell power generation unit is connected to the syngas preparation unit and is used to convert the chemical energy in the syngas into electrical energy and thermal energy.

[0010] The waste heat utilization unit is connected to the solid oxide fuel cell power generation unit and is used to recover and utilize the waste heat of the high-temperature flue gas generated by the solid oxide fuel cell power generation unit. The high-temperature heat energy is converted into electrical energy, heat energy and cold energy through steam cycle and transcritical CO2 refrigeration cycle.

[0011] The Carnot battery energy storage unit is connected to the wind power generation system, the solid oxide fuel cell power generation unit, and the waste heat utilization unit. It is used to receive excess electrical energy from each unit and convert it into heat energy. When needed, it converts heat energy into electrical energy, heat energy, and cold energy to regulate the system's supply and demand balance and achieve multi-energy complementary output.

[0012] Furthermore, the syngas preparation unit includes a methanol storage tank, a methanol pump, a photovoltaic-thermal integrated utilization device, a first heat exchanger, a methanol reactor, a nanofluid circulation component, a syngas compressor, and a syngas storage tank. The methanol storage tank is connected to the methanol reactor via the methanol pump, the photovoltaic-thermal integrated utilization device, and the first heat exchanger. The outlet of the methanol reactor is connected to the syngas storage tank via the first heat exchanger and the syngas compressor. The syngas storage tank is used to supply fuel to the solid oxide fuel cell power generation unit. The nanofluid circulation component includes a nanofluid storage tank and a nanofluid pump. The nanofluid storage tank is connected to the methanol reactor via the nanofluid pump and the photovoltaic-thermal integrated utilization device, forming a nanofluid circulation loop to provide heat energy for the methanol reaction.

[0013] Furthermore, the photovoltaic-thermal integrated utilization device adopts a trough solar collector or a linear Fresnel collector; the nanofluid absorbs solar energy in the photovoltaic-thermal integrated utilization device and its temperature rises to 200-300℃ before entering the methanol reactor.

[0014] Furthermore, the solid oxide fuel cell power generation unit includes an air treatment component, a syngas preheater, a solid oxide fuel cell, an afterburner, a flue gas turbine, and a first generator; the air treatment component is connected to the SOFC cathode via the syngas preheater, and the syngas output from the syngas preparation unit is connected to the SOFC anode via the syngas preheater; the outlets of both the SOFC cathode and anode are connected to the afterburner, and the outlet of the afterburner is connected to the waste heat utilization unit via the flue gas turbine and the syngas preheater; the first generator is coaxially connected to the flue gas turbine to convert the mechanical energy of the flue gas turbine into electrical energy.

[0015] Furthermore, the solid oxide fuel cell power generation unit also includes a DC / AC converter, which is connected to the SOFC output terminal to convert the DC power generated by the SOFC into AC power.

[0016] Furthermore, the waste heat utilization unit includes a steam circulation assembly and a transcritical CO2 refrigeration cycle assembly. The steam circulation assembly includes a waste heat boiler, a steam turbine, a second generator, a condenser, and a feedwater pump. The waste heat boiler forms a circulation loop through the steam turbine, condenser, and feedwater pump. The second generator is coaxially connected to the steam turbine. The transcritical CO2 refrigeration cycle assembly includes a CO2 evaporator, a CO2 compressor, a CO2 cooler, a CO2 turbine, and a third generator. The CO2 evaporator forms a circulation loop through the CO2 compressor, CO2 cooler, and CO2 turbine. The third generator is coaxially connected to the CO2 turbine. The condenser is connected to the CO2 evaporator via a circulating water pump, providing a cold source for the transcritical CO2 refrigeration cycle assembly.

[0017] Furthermore, the Carnot battery energy storage unit includes a heat exchange assembly, a heat pump cycle assembly, a thermal storage cycle assembly, an organic Rankine power generation cycle assembly, and a jet refrigeration cycle assembly; the heat exchange assembly includes a separation valve, a second heat exchanger, and a third heat exchanger, with one end of the separation valve connected to the second and third heat exchangers via the second heat exchanger, and the other end connected to the third heat exchanger via a fourth heat exchanger, and the separation valve is connected to the waste heat utilization unit; the heat pump cycle assembly includes an expansion valve, a fourth heat exchanger, a compressor, and a high-temperature heat exchanger, with the expansion valve, the fourth heat exchanger, the compressor, and the high-temperature heat exchanger forming a circulation loop; the thermal storage cycle assembly includes a high-temperature storage tank, a low-temperature storage tank, a high-temperature heat exchanger, a low-temperature heat exchanger, a second valve, and... The third valve, the fifth heat exchanger, the high-temperature storage tank, the low-temperature heat exchanger, the fifth heat exchanger, the third valve, the low-temperature storage tank, the high-temperature heat exchanger, and the second valve are sequentially connected to form a loop; the organic Rankine power generation cycle assembly includes a low-temperature heat exchanger, an expander, a fourth generator, an organic working fluid condenser, and an organic working fluid circulation pump. The low-temperature heat exchanger, the expander, the organic working fluid condenser, and the organic working fluid circulation pump form a circulation loop, and the fourth generator is coaxially connected to the expander; the jet refrigeration cycle assembly includes an organic working fluid evaporator, an ejector, an organic working fluid condenser, and an organic working fluid expansion valve. The organic working fluid evaporator forms a circulation loop via the ejector, the organic working fluid condenser, and the organic working fluid expansion valve.

[0018] Furthermore, in the Carnot battery energy storage unit, the electrical energy consumed by the compressor is the electrical energy generated by each power generation unit of the system that exceeds the load demand; the ratio of electrical energy and cold energy supplied by the Carnot battery energy storage unit is adjusted by regulating the fluid flow ratio from the outlet of the cryogenic heat exchanger to the expander and ejector.

[0019] According to a second aspect of the present invention, the present invention provides an optimization method for a wind-solar hybrid power supply system integrating Carnot batteries, applied to the aforementioned wind-solar hybrid power supply system integrating Carnot batteries, comprising the following steps:

[0020] Step 1: Obtain meteorological data for the system's location, including solar radiation data, ambient temperature, and local wind speed;

[0021] Step 2: Input the system's technical parameters, economic parameters, environmental parameters, and electrical load, heat load, and cooling load demand data;

[0022] Step 3: Based on the laws of conservation of mass and energy, and the supply and demand balance condition, construct a system energy supply model;

[0023] Step 4: Determine the system optimization variables and input initial values. The optimization variables include the capacity of the photovoltaic-thermal integrated utilization device, the capacity of the wind turbine generator, the capacity of the solid oxide fuel cell, the design parameters of the high-temperature storage tank and the low-temperature storage tank, and the system operation process parameters.

[0024] Step 5: Using the minimum system failure rate, the lowest levelized energy cost, and the maximum annual carbon emission reduction as optimization objectives, the multi-objective particle swarm optimization algorithm is used to optimize the optimization variables to obtain the Pareto optimal boundary.

[0025] Step 6: Use the superior-inferior solution distance method to screen the solutions in the Pareto optimal boundary and obtain the optimal optimization result.

[0026] Furthermore, the optimization objectives are divided into three aspects: stability, economy, and environmental protection, which are characterized by the failure rate, levelized cost of energy, and annual carbon emission reduction, respectively.

[0027] The load failure rate is calculated as follows:

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] In the formula, LOLP and LOLP e LOLP h LOLP c These are the system failure rate, electrical load failure rate, thermal load failure rate, and cooling load failure rate, respectively; n e n h n cThese are the weighting coefficients for electrical load failure rate, thermal load failure rate, and cooling load failure rate, respectively; ΔE, ΔH, and ΔC are the electrical load failure value, thermal load failure value, and cooling load failure value, respectively; E load H load C load These are electrical load, thermal load, and cooling load, respectively; E PV E W E SOFC E1, E2, E3, and E4 represent the power generation of photovoltaic power, wind power, SOFC power, the power generation of the first generator, the power generation of the second generator, the power generation of the third generator, and the power generation of the fourth generator, respectively; H1, H2, H3, and H4 represent the heat supply of the CO2 cooler, the second heat exchanger, the third heat exchanger, and the fifth heat exchanger, respectively; C1 and C2 represent the cooling capacity of the CO2 evaporator and the organic working fluid evaporator, respectively.

[0036] The levelized energy cost is calculated as follows:

[0037]

[0038] In the formula, CRF is the capital recovery rate; Fix is ​​the total cost of building the system; O&M is the annual operating cost of the system; C f The annual methanol cost is represented by E, H, and C, which represent the system's annual power supply, heat supply, and cooling capacity, respectively.

[0039] The annual carbon emission reduction is calculated as follows:

[0040]

[0041]

[0042]

[0043] In the formula, CE ref CE sys These represent the carbon emissions of the reference system and the current system, respectively; α is the carbon emission coefficient of the grid electricity; φ h φ c These are the electric heating efficiency and electric cooling efficiency, respectively; Em a&p Carbon emissions from the acquisition of raw materials for system equipment and the equipment manufacturing process; Em ope Carbon emissions during system operation.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention is equipped with a syngas preparation unit, a wind power generation system, a solid oxide fuel cell power generation unit, a waste heat utilization unit, and a Carnot battery energy storage unit. Through the synergistic cooperation of these five units, the problems of low efficiency and difficulty in energy storage of traditional photovoltaic and thermal systems are solved, the system performance deterioration caused by the mismatch between energy supply and load is alleviated, the curtailment rate of solar and wind power is reduced, and stable multi-energy output and low-carbon economic operation are achieved, which meets the development needs of efficient, reliable and environmentally friendly distributed energy supply systems. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of the integrated Carnot battery solar cogeneration system provided by the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of a parabolic trough and Fresnel photovoltaic-thermal integrated utilization device;

[0047] Figure 3 This is a flowchart of the optimization method for the wind-solar hybrid power system with integrated Carnot batteries provided by the present invention.

[0048] In the diagram: 1. Syngas preparation unit; 101. Methanol storage tank; 102. Methanol pump; 103. Photovoltaic-thermal integrated utilization device; 103.1. Photovoltaic cell; 103.2. Methanol fluid channel; 103.3. Quartz glass tube; 103.4. Nanofluid channel; 103.5. Parabolic trough reflector; 103.6. Linear Fresnel lens; 104. First heat exchanger; 105. Methanol reactor; 106. Nanofluid storage tank; 107. Nanofluid pump; 108. Syngas compressor; 109. Syngas storage tank; 110. First valve;

[0049] 2. Wind power generation system;

[0050] 3. Solid oxide fuel cell power generation unit; 301. Air compressor; 302. Air preheater; 303. Syngas preheater; 304. Solid oxide fuel cell; 305. DC / AC converter; 306. Aftercombustion chamber; 307. Flue gas turbine; 308. First generator;

[0051] 4. Waste heat utilization unit; 401. Waste heat boiler; 402. Steam turbine; 403. Second generator; 404. Condenser; 405. Feed water pump; 406. Circulating water pump; 407. CO2 evaporator; 408. CO2 compressor; 409. CO2 cooler; 410. CO2 turbine; 411. Third generator;

[0052] 5. Carnot battery energy storage unit; 501. Separation valve; 502. Second heat exchanger; 503. Third heat exchanger; 504. Expansion valve; 505. Fourth heat exchanger; 506. Compressor; 507. High-temperature heat exchanger; 508. Second valve; 509. High-temperature storage tank; 510. Low-temperature heat exchanger; 511. Fifth heat exchanger; 512. Third valve; 513. Low-temperature storage tank; 514. Organic working fluid circulation pump; 515. Expander; 516. Fourth generator; 517. Ejector; 518. Organic working fluid condenser; 519. Organic working fluid expansion valve; 520. Organic working fluid evaporator. Detailed Implementation

[0053] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details:

[0055] Example 1

[0056] like Figure 1 As shown, this embodiment provides a solar cogeneration system integrating a Carnot battery, including a syngas production unit 1, a wind power generation system 2, a solid oxide fuel cell power generation unit 3, a waste heat utilization unit 4, and a Carnot battery energy storage unit 5.

[0057] Specifically, the system includes a methanol storage tank 101, a methanol pump 102, a photovoltaic-thermal integrated utilization device 103, a first heat exchanger 104, a methanol reactor 105, a nanofluid storage tank 106, a nanofluid pump 107, a syngas compressor 108, a syngas storage tank 109, a first valve 110, a wind power generation system 2, an air compressor 301, an air preheater 302, a syngas preheater 303, a solid oxide fuel cell 304, a DC / AC converter 305, an afterburner 306, a flue gas turbine 307, a first generator 308, a waste heat boiler 401, a steam turbine 402, a second generator 403, a condenser 404, a feedwater pump 405, and a circulating water system. Circulating water pump 406, CO2 evaporator 407, CO2 compressor 408, CO2 cooler 409, CO2 turbine 410, third generator 411, separation valve 501, second heat exchanger 502, third heat exchanger 503, expansion valve 504, fourth heat exchanger 505, compressor 506, high-temperature heat exchanger 507, second valve 508, high-temperature storage tank 509, low-temperature heat exchanger 510, fifth heat exchanger 511, third valve 512, low-temperature storage tank 513, organic working fluid circulating pump 514, expander 515, fourth generator 516, ejector 517, organic working fluid condenser 518, organic working fluid expansion valve 519, organic working fluid evaporator 520.

[0058] The structure of the photovoltaic-thermal integrated utilization device 103 is as follows: Figure 2 As shown, the device includes a photovoltaic cell 103.1, a methanol fluid channel 103.2, a quartz glass tube 103.3, a nanofluid channel 103.4, a parabolic trough-type reflector 103.5, and a linear Fresnel lens 103.6. Sunlight shines onto the photovoltaic-thermal integrated utilization device 103, and is focused onto the heat collection tube by reflection from the trough-type reflector or refraction from the linear Fresnel lens. After the nanofluid selectively transmits the solar spectrum, wavelengths compatible with the photovoltaic cell are transmitted to the photovoltaic cell for photoelectric utilization, while the remaining wavelengths are absorbed by the nanofluid for photothermal utilization.

[0059] Depending on the intensity of solar irradiance, the nanofluid stored in nanofluid storage tank 106 flows through the nanofluid channels of the photovoltaic-thermal integrated utilization device 103 under the drive of nanofluid pump 107, absorbing solar energy and raising its temperature to approximately 200-300°C. It then enters methanol reactor 105 to provide energy for the methanol decomposition reaction. After releasing heat, the nanofluid returns to nanofluid storage tank 106 for the next cycle. Methanol stored in methanol storage tank 101 flows through the fluid channels on the back of the photovoltaic cells in the photovoltaic-thermal integrated utilization device 103 under the drive of methanol pump 102, absorbing the waste heat generated by the photovoltaic cells and raising its temperature. The methanol exiting the photovoltaic-thermal integrated utilization device 103 enters the first heat exchanger 104 for further preheating to saturation temperature, and then enters methanol reactor 105 for decomposition to generate syngas (mainly containing CO, H2, and some unreacted methanol). The generated syngas is pressurized by syngas compressor 108 and stored in syngas storage tank 109.

[0060] Wind turbine 2 is used to convert wind energy into electrical energy.

[0061] Under the same external load conditions, air is pressurized to a certain pressure by air compressor 301 and then enters air preheater 302. After being preheated by the exhaust gas from the flue gas turbine, it enters the cathode channel of solid oxide fuel cell 304. At the cathode of the solid oxide fuel cell, O2 in the air gains electrons and becomes O2. 2- Syngas stored in syngas storage tank 109 passes through first valve 110 and enters syngas preheater 303. After being preheated by the exhaust gas from the flue gas turbine, it enters the anode channel of solid oxide fuel cell 304. At the anode of the solid oxide fuel cell, H2 in the syngas reacts with O2 generated at the cathode. 2- An electrochemical reaction occurs, releasing electrons and generating H2O. The DC / AC converter 305 is connected to the output of the solid oxide fuel cell 304, outputting electrical energy. The cathode exhaust of the solid oxide fuel cell (mainly containing N2 and O2) enters the aftercombustion chamber 306 and mixes with the anode exhaust, where it is burned. The anode exhaust of the solid oxide fuel cell (mainly containing CO, H2, H2O, and methanol) enters the aftercombustion chamber 306 and mixes with the cathode exhaust, burning and consuming unreacted syngas. The flue gas from the outlet of the aftercombustion chamber 306 (mainly containing H2O, N2, O2, and CO2) enters the flue gas turbine 307, expands, and performs work. It then flows sequentially through the syngas preheater 303, air preheater 302, and waste heat boiler 401 before entering the separation valve 501. The first generator 308 is coaxially connected to the flue gas turbine 307, outputting electrical energy.

[0062] The flue gas entering the waste heat boiler 401 has a temperature of approximately 700℃, serving as a heat source for the boiler. Feedwater entering the waste heat boiler 401 absorbs the heat released by the flue gas, becoming superheated steam, which then enters the steam turbine 402 to expand and perform work. The exhaust steam from the steam turbine 402 exits into the condenser 404, releasing heat and becoming condensate. It then re-enters the waste heat boiler 401 under the drive of the feedwater pump 405 for the next cycle. As a cooling medium, circulating water enters the condenser 404, absorbs the heat released by the condensation of exhaust steam, and then, driven by the circulating water pump 406, enters the CO2 evaporator 407, releasing heat before returning to the condenser 404. Liquid CO2 flows through the CO2 evaporator 407, absorbing heat and becoming gaseous CO2, simultaneously providing cooling energy to the outside. The CO2 gas exiting the CO2 evaporator 407 is compressed by the CO2 compressor 408 and then enters the CO2 cooler 409 for cooling, providing heat energy to the outside. CO2 from the outlet of CO2 cooler 409 enters CO2 turbine 410, expands, and performs work, then returns to CO2 evaporator 407. A third generator 411 is coaxially connected to CO2 turbine 410, outputting electrical energy.

[0063] The flue gas from the outlet of waste heat boiler 401 is divided into two paths by separation valve 501. One path flows sequentially through the second heat exchanger 502 and the third heat exchanger 503 to provide heat energy to the outside; the other path passes through the fourth heat exchanger 505 to provide heat energy to the Carnot battery energy storage system, and then also enters the third heat exchanger 503 to provide heat energy to the outside. The organic working fluid absorbs heat after flowing through the fourth heat exchanger 505, and then flows sequentially through the compressor 506, the high-temperature heat exchanger 507, and the expansion valve 504 to form a heat pump cycle. The electrical energy consumed by the compressor 506 comes from the portion of the total power generated by all power generation devices in the system that exceeds the system's electrical load. The heat storage working fluid from the cryogenic storage tank 513 absorbs heat after flowing through the high-temperature heat exchanger 507, then flows through the second valve 508, and is finally stored in the high-temperature storage tank 509. Based on the supply and demand relationship between the system output and the external load, the heat storage medium stored in the high-temperature storage tank 509 flows through the low-temperature heat exchanger 510 to release heat and provide thermal energy for the organic Rankine cycle. It then flows through the fifth heat exchanger 511 to provide heat load to the outside environment, and finally flows through the third valve 512 before being stored in the low-temperature storage tank 513. The working medium of the organic Rankine cycle is an organic working medium. The liquid organic working medium absorbs heat and vaporizes in the low-temperature heat exchanger 510 until it reaches saturation. Afterward, it enters the expander 515 to expand and perform work, driving the fourth generator 516 to output electrical energy. The organic working medium after performing work enters the organic working medium condenser 518 to release heat and condense. The condensed organic working medium is pressurized by the organic working medium circulation pump 514 and then re-enters the low-temperature heat exchanger 510 for the next cycle.

[0064] In the jet refrigeration cycle coupled with the organic Rankine cycle, the working medium is the same as that of the organic Rankine cycle, namely, an organic working fluid. The high-temperature, high-pressure organic working fluid flowing out of the cryogenic heat exchanger 510 is divided into two parts. One part enters the expander 515, and the other part enters the ejector 517 and is ejected at supersonic speed after passing through the expanding and contracting nozzles. A low-pressure zone is generated near the nozzles, thereby drawing the low-pressure organic working fluid in the organic working fluid evaporator 520 into the ejector 517. After the two working fluids mix, a medium-pressure organic working fluid is formed. The formed medium-pressure organic working fluid mixes with the organic working fluid at the outlet of the expander 515 and then enters the organic working fluid condenser 518 for exothermic condensation. The condensed organic working fluid is divided into two parts. One part is pressurized by the organic working fluid circulation pump 514 and enters the cryogenic heat exchanger 510 to absorb heat and vaporize; the other part is depressurized by the organic working fluid expansion valve 519 and enters the organic working fluid evaporator 520 to absorb heat and vaporize, thus outputting cold energy.

[0065] This invention constructs a multi-unit collaborative wind-solar hybrid power system by setting up a syngas production unit 1, a wind power generation system 2, a solid oxide fuel cell power generation unit 3, a waste heat utilization unit 4, and a Carnot battery energy storage unit 5. This system specifically addresses the pain points of existing technologies: the syngas production unit 1 converts solar energy into electrical and thermal energy, and further uses thermal energy to drive a reaction to generate syngas for chemical energy storage, providing a stable source of solar-derived energy for the system; the wind power generation system 2 converts wind energy into electrical energy, broadening the input path for clean energy; both systems together increase the proportion of renewable energy utilization and reduce the curtailment rate of solar and wind power; the solid oxide fuel cell power generation unit 3... The chemical energy in the syngas is converted into electrical and thermal energy, achieving efficient energy conversion and utilization. The waste heat utilization unit 4 recovers the waste heat from the high-temperature flue gas generated by the solid oxide fuel cell power generation unit 3, and outputs electrical, thermal, and cold energy through energy conversion, thereby improving the overall energy utilization rate of the system. The Carnot battery energy storage unit 5 plays an energy regulation and buffering role among the units, storing the excess electrical and thermal energy generated by each unit. When wind and solar resources are insufficient or the load fluctuates, the energy is released to ensure the supply and demand balance between the energy supply side and the energy consumption side, and to avoid the system's performance deterioration due to variable operating conditions. Ultimately, the goal of efficient, stable, and low-carbon operation of the distributed energy supply system is achieved.

[0066] Therefore, by setting up a syngas preparation unit 1, a wind power generation system 2, a solid oxide fuel cell power generation unit 3, a waste heat utilization unit 4, and a Carnot battery energy storage unit 5, and through the coordinated operation of these five units, the present invention not only solves the problems of low efficiency and difficulty in energy storage of traditional photovoltaic and thermal systems, but also alleviates the system performance degradation caused by the mismatch between energy supply and load, while reducing the curtailment rate of solar and wind power, and achieving stable multi-energy output and low-carbon economic operation, which meets the development needs of efficient, reliable and environmentally friendly distributed energy supply systems.

[0067] Example 2

[0068] like Figure 3 As shown in the figure, this embodiment provides an optimization method for a wind-solar hybrid power system integrating Carnot batteries. The specific steps are as follows:

[0069] S1. Obtain meteorological data for the system's location, including hourly data on solar radiation, ambient temperature, and local wind speed for a typical year.

[0070] S2. Input known parameters such as system technical parameters, economic parameters, environmental parameters, electrical load, thermal load, and cooling load.

[0071] S3. Based on the principles of mass conservation, energy conservation, and supply-demand balance, construct a system energy supply model.

[0072] S4. Input the initial values ​​of the system optimization variables. The system optimization variables can be selected from the capacity of the photovoltaic-thermal integrated utilization device, the capacity of the wind turbine generator, the capacity of the solid oxide fuel cell, the design conditions of the high-temperature storage tank and the low-temperature storage tank, as well as the system operation process parameters.

[0073] S5. Based on typical annual meteorological data and system functional models, the annual operating characteristics of the system are simulated hourly. With minimum load factor, minimum levelized energy cost, and maximum annual carbon emission reduction as optimization objectives, a multi-objective particle swarm optimization algorithm is used to optimize the system's optimization variables, obtaining the Pareto boundary.

[0074] The optimization objectives of the system are divided into three aspects: stability, economy and environmental protection, which are characterized by the failure rate, levelized cost of energy and annual carbon emission reduction, respectively.

[0075] The failure rate is calculated as follows:

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] In the formula, LOLP and LOLP e LOLP h LOLP c These are the system failure rate, electrical load failure rate, thermal load failure rate, and cooling load failure rate, respectively; n en h n c These are the weighting coefficients for electrical load failure rate, thermal load failure rate, and cooling load failure rate, respectively; ΔE, ΔH, and ΔC are the electrical load failure value, thermal load failure value, and cooling load failure value, respectively; E load H load C load These are electrical load, thermal load, and cooling load, respectively; E PV E W E SOFC E1, E2, E3, and E4 represent the power generation of photovoltaic power, wind power, SOFC power, the power generation of the first generator, the power generation of the second generator, the power generation of the third generator, and the power generation of the fourth generator, respectively; H1, H2, H3, and H4 represent the heat supply of the CO2 cooler, the second heat exchanger, the third heat exchanger, and the fifth heat exchanger, respectively; C1 and C2 represent the cooling capacity of the CO2 evaporator and the organic working fluid evaporator, respectively.

[0084] The levelized cost of energy (LCOE) is calculated as follows:

[0085]

[0086] In the formula, CRF is the capital recovery rate; Fix is ​​the total cost of building the system; O&M is the annual operating cost of the system; C f E represents the annual methanol cost; E, H, and C represent the system's annual power supply, heat supply, and cooling supply, respectively.

[0087] The annual carbon emission reduction is calculated as follows:

[0088]

[0089]

[0090]

[0091] In the formula, CE ref CE sys These represent the carbon emissions of the reference system and the current system, respectively; α is the carbon emission coefficient of the grid electricity; φ h φ c These are the electric heating efficiency and the electric cooling efficiency, respectively. a&p Carbon emissions from the acquisition of raw materials for system equipment and the equipment manufacturing process; Em ope Carbon emissions during system operation.

[0092] Step 6: Obtain the optimization results using the Top-Inferior Solution Distance Method (TOPSIS).

[0093] In summary, the present invention has the following beneficial effects:

[0094] 1. This invention includes a photovoltaic-thermal integrated utilization device 103. Sunlight shines onto the device 103 and is reflected by a parabolic trough reflector 103.5 or refracted by a linear Fresnel lens 103.6, focusing onto the heat collection tube. After the solar spectrum is divided by nanofluid, wavelengths compatible with the photovoltaic cell 103.1 are applied to the photovoltaic cell 103.1 for photoelectric utilization, while the remaining wavelengths are absorbed by the nanofluid for photothermal utilization. Furthermore, the optical properties of the nanofluid can be altered by changing parameters such as the nanoparticle material, particle size, shape, and concentration, allowing it to be matched with the spectral response bands of different types of photovoltaic cells 103.1, fully utilizing the energy of different wavelengths of solar energy, thereby improving the efficiency of solar energy utilization.

[0095] 2. This invention converts low-grade solar thermal energy into high-grade chemical energy stored in syngas. It features high energy storage density, a simple energy storage device structure, and small volume. Furthermore, by utilizing the syngas through a solid oxide fuel cell 304 instead of direct combustion, the utilization rate of the syngas is improved. Therefore, this invention effectively solves the problems of difficult energy storage, high cost, and low efficiency in the process of solar energy utilization.

[0096] 3. The CO and a small amount of methanol in the synthesis gas generated by this invention can be directly burned in the aftercombustion chamber 306, reducing the need for related separation devices and simplifying the system and its cost. Furthermore, the heat released during combustion increases the temperature of the flue gas in the aftercombustion chamber 306, thereby increasing the inlet temperature of the flue gas turbine 307 and increasing its output power.

[0097] 4. When external wind and solar resources are poor, the syngas preparation unit 1 and the wind power generation system 2 will not operate, but the system can still rely on the solid oxide fuel cell power generation unit 3, the waste heat utilization unit 4 and the Carnot battery energy storage unit 5 to ensure the supply of cold, heat and electricity, and ensure the continuous operation of the system.

[0098] 5. This invention includes a Carnot battery energy storage unit 5, which serves as a means of regulating the supply and demand relationship between the system's energy supply and external loads. When other sub-units of the system are not operating, the energy release process of the Carnot battery energy storage unit 5 alone can output electrical energy, heat energy, and cold energy to meet the external electrical, heat, and cold load demands, thus ensuring the continuous operation of the system and improving its stability.

[0099] 6. The present invention uses a syngas storage tank 109 and a Carnot battery energy storage unit 5, which can greatly reduce the high curtailment rates of solar and wind power in the current renewable energy utilization process. By storing the electrical energy generated by solar, wind and other power generation equipment in the Carnot battery energy storage unit 5, the storage cost of electrical energy is greatly reduced and the economic efficiency is improved.

[0100] 7. The optimization objectives of the multi-objective optimization process of this invention take into account the stability, economy and environmental protection of the system. The optimization variables can be selected from the design parameters or system operation parameters of the photovoltaic-thermal integrated utilization device 103, the wind power generation system 2, the solid oxide fuel cell 304, the high temperature storage tank 509, and the low temperature storage tank 513.

[0101] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wind-solar hybrid power supply system integrating Carnot batteries, characterized in that, include: The syngas preparation unit is used to convert solar energy into electrical and thermal energy, and then use thermal energy to assist in the decomposition of methanol, thereby converting solar energy into chemical energy stored in syngas. Wind power generation systems are used to convert wind energy into electrical energy; The solid oxide fuel cell power generation unit is connected to the syngas preparation unit and is used to convert the chemical energy in the syngas into electrical energy and thermal energy. The waste heat utilization unit is connected to the solid oxide fuel cell power generation unit and is used to recover and utilize the waste heat of the high-temperature flue gas generated by the solid oxide fuel cell power generation unit. The high-temperature heat energy is converted into electrical energy, heat energy and cold energy through steam cycle and transcritical CO2 refrigeration cycle. The Carnot battery energy storage unit is connected to the wind power generation system, the solid oxide fuel cell power generation unit, and the waste heat utilization unit. It is used to receive excess electrical energy from each unit and convert it into heat energy. When needed, it converts heat energy into electrical energy, heat energy, and cold energy to regulate the system's supply and demand balance and achieve multi-energy complementary output.

2. The wind-solar hybrid power system with integrated Carnot batteries according to claim 1, characterized in that, The syngas preparation unit includes a methanol storage tank, a methanol pump, a photovoltaic-thermal integrated utilization device, a first heat exchanger, a methanol reactor, a nanofluid circulation component, a syngas compressor, and a syngas storage tank. The methanol storage tank is connected to the methanol reactor via the methanol pump, the photovoltaic-thermal integrated utilization device, and the first heat exchanger. The outlet of the methanol reactor is connected to the syngas storage tank via the first heat exchanger and the syngas compressor. The syngas storage tank is used to supply fuel to the solid oxide fuel cell power generation unit. The nanofluid circulation component includes a nanofluid storage tank and a nanofluid pump. The nanofluid storage tank is connected to the methanol reactor via the nanofluid pump and the photovoltaic-thermal integrated utilization device, forming a nanofluid circulation loop to provide heat energy for the methanol reaction.

3. The wind-solar hybrid power supply system with integrated Carnot batteries according to claim 2, characterized in that, The photovoltaic-thermal integrated utilization device adopts a trough solar collector or a linear Fresnel collector; the nanofluid absorbs solar energy in the photovoltaic-thermal integrated utilization device and its temperature rises to 200-300℃ before entering the methanol reactor.

4. The wind-solar hybrid power supply system with integrated Carnot batteries according to claim 1, characterized in that, The solid oxide fuel cell power generation unit includes an air treatment component, a syngas preheater, a solid oxide fuel cell, an afterburner, a flue gas turbine, and a first generator. The air treatment component is connected to the SOFC cathode via the syngas preheater, and the syngas output from the syngas preparation unit is connected to the SOFC anode via the syngas preheater. The outlets of both the SOFC cathode and anode are connected to the afterburner, and the outlet of the afterburner is connected to the waste heat utilization unit via the flue gas turbine and the syngas preheater. The first generator is coaxially connected to the flue gas turbine to convert the mechanical energy of the flue gas turbine into electrical energy.

5. The wind-solar hybrid power supply system with integrated Carnot batteries according to claim 4, characterized in that, The solid oxide fuel cell power generation unit also includes a DC / AC converter, which is connected to the SOFC output terminal to convert the DC power generated by the SOFC into AC power.

6. The wind-solar hybrid power supply system with integrated Carnot batteries according to claim 1, characterized in that, The waste heat utilization unit includes a steam circulation assembly and a transcritical CO2 refrigeration cycle assembly. The steam circulation assembly includes a waste heat boiler, a steam turbine, a second generator, a condenser, and a feedwater pump. The waste heat boiler forms a circulation loop through the steam turbine, condenser, and feedwater pump. The second generator is coaxially connected to the steam turbine. The transcritical CO2 refrigeration cycle assembly includes a CO2 evaporator, a CO2 compressor, a CO2 cooler, a CO2 turbine, and a third generator. The CO2 evaporator forms a circulation loop through the CO2 compressor, CO2 cooler, and CO2 turbine. The third generator is coaxially connected to the CO2 turbine. The condenser is connected to the CO2 evaporator via a circulating water pump, providing a cold source for the transcritical CO2 refrigeration cycle assembly.

7. The wind-solar hybrid power supply system with integrated Carnot batteries according to claim 1, characterized in that, The Carnot battery energy storage unit includes a heat exchange assembly, a heat pump cycle assembly, a thermal storage cycle assembly, an organic Rankine power generation cycle assembly, and a jet refrigeration cycle assembly. The heat exchange assembly includes a separation valve, a second heat exchanger, and a third heat exchanger. One end of the separation valve is connected to the second and third heat exchangers via the second and third heat exchangers, and the other end is connected to the third heat exchanger via a fourth heat exchanger. The separation valve is connected to a waste heat recovery unit. The heat pump cycle assembly includes an expansion valve, a fourth heat exchanger, a compressor, and a high-temperature heat exchanger. The expansion valve, fourth heat exchanger, compressor, and high-temperature heat exchanger form a circulation loop. The thermal storage cycle assembly includes a high-temperature storage tank, a low-temperature storage tank, a high-temperature heat exchanger, a low-temperature heat exchanger, a second valve, and a third valve. The system consists of a door, a fifth heat exchanger, a high-temperature storage tank, a low-temperature heat exchanger, a fifth heat exchanger, a third valve, a low-temperature storage tank, a high-temperature heat exchanger, and a second valve, which are connected in sequence to form a loop. The organic Rankine power generation cycle assembly includes a low-temperature heat exchanger, an expander, a fourth generator, an organic working fluid condenser, and an organic working fluid circulation pump. The low-temperature heat exchanger, expander, organic working fluid condenser, and organic working fluid circulation pump form a circulation loop, and the fourth generator is coaxially connected to the expander. The jet refrigeration cycle assembly includes an organic working fluid evaporator, an ejector, an organic working fluid condenser, and an organic working fluid expansion valve. The organic working fluid evaporator forms a circulation loop via the ejector, organic working fluid condenser, and organic working fluid expansion valve.

8. The wind-solar hybrid power system with integrated Carnot batteries according to claim 7, characterized in that, In the Carnot battery energy storage unit, the electrical energy consumed by the compressor is the electrical energy generated by each power generation unit of the system that exceeds the load demand; the ratio of electrical energy and cold energy supplied by the Carnot battery energy storage unit is adjusted by regulating the ratio of fluid flow from the outlet of the cryogenic heat exchanger to the expander and the ejector.

9. An optimization method for a wind-solar hybrid power generation system integrating Carnot batteries, applied to the wind-solar hybrid power generation system integrating Carnot batteries as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Obtain meteorological data for the system's location, including solar radiation data, ambient temperature, and local wind speed; Step 2: Input the system's technical parameters, economic parameters, environmental parameters, and electrical load, heat load, and cooling load demand data; Step 3: Based on the laws of conservation of mass and energy, and the supply and demand balance condition, construct a system energy supply model; Step 4: Determine the system optimization variables and input their initial values; Step 5: Using the minimum system failure rate, the lowest levelized energy cost, and the maximum annual carbon emission reduction as optimization objectives, the multi-objective particle swarm optimization algorithm is used to optimize the optimization variables to obtain the Pareto optimal boundary. Step 6: Use the superior-inferior solution distance method to screen the solutions in the Pareto optimal boundary and obtain the optimal optimization result.

10. The optimization method for a wind-solar hybrid power system with integrated Carnot batteries according to claim 9, characterized in that, The optimization objectives are divided into three aspects: stability, economy, and environmental protection, which are characterized by the failure rate, levelized cost of energy, and annual carbon emission reduction, respectively. The load failure rate is calculated as follows: In the formula, LOLP, LOLP e LOLP h LOLP c These are the system failure rate, electrical load failure rate, thermal load failure rate, and cooling load failure rate, respectively; n e n h n c These are the weighting coefficients for electrical load failure rate, thermal load failure rate, and cooling load failure rate, respectively; ΔE, ΔH, and ΔC are the electrical load failure values, thermal load failure values, and cooling load failure values, respectively; E load H load C load These are electrical load, thermal load, and cooling load, respectively; E PV E W E SOFC E1, E2, E3, and E4 represent the power generation of photovoltaic power, wind power, SOFC power, the power generation of the first generator, the power generation of the second generator, the power generation of the third generator, and the power generation of the fourth generator, respectively; H1, H2, H3, and H4 represent the heat supply of the CO2 cooler, the second heat exchanger, the third heat exchanger, and the fifth heat exchanger, respectively; C1 and C2 represent the cooling capacity of the CO2 evaporator and the organic working fluid evaporator, respectively. The levelized energy cost is calculated as follows: In the formula, CRF is the capital recovery rate; Fix is ​​the total cost of building the system; O&M is the annual operating cost of the system; C f The annual methanol cost is represented by E, H, and C, which represent the system's annual power supply, heat supply, and cooling capacity, respectively. The annual carbon emission reduction is calculated as follows: In the formula, CE ref CE sys These represent the carbon emissions of the reference system and the current system, respectively; α is the carbon emission coefficient of the grid electricity; φ h φ c These are the electric heating efficiency and the electric cooling efficiency, respectively. Em a&p Carbon emissions from the acquisition of raw materials for system equipment and the equipment manufacturing process; Em ope Carbon emissions during system operation.

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