Regional multi-energy control system and method

Abstract

According to the regional multi-energy control system and method, CO2, H2O, H2, O2 and CH4 are recycled through a methanation reactor, a deep coupling supercritical carbon dioxide combined heat and power generation unit, a water electrolysis hydrogen production system, a biogas digester and a biogas purification device, and near-zero emission of carbon dioxide is achieved; during operation, rural renewable energy sources are fully utilized, and multi-energy-form output of cold, heat, electricity, gas and the like is achieved. By the adoption of the technical scheme, the energy utilization efficiency of the system can be effectively improved, and the purposes of energy conservation, emission reduction and cost reduction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of regional distributed multi-energy systems, and in particular relates to a regional multi-energy control system and method based on a supercritical carbon dioxide cogeneration unit. Background Art

[0002] With the continuous growth of rural economy and the increasing number of rural industries, rural energy demand is gradually showing a trend of diversification, cleanness and electrification. The traditional rural distributed multi-energy system has initially established a microgrid that couples wind, solar and storage integration, and has achieved the primary utilization of biomass energy such as livestock manure through biogas digesters, but there is still much room for improvement in energy utilization and carbon emission reduction. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a regional multi-energy control system and method based on a supercritical carbon dioxide cogeneration unit, which can effectively improve the energy utilization efficiency of the system and achieve the goals of energy saving, emission reduction and cost reduction.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A regional multi-energy control system includes: a wind turbine, a photovoltaic unit, a solar thermal unit, a water electrolysis hydrogen production system, a methanation reactor, a supercritical carbon dioxide cogeneration unit, an electric refrigeration system, a biogas tank, a biogas purification device, and a natural gas storage center; wherein, through the methanation reactor, the supercritical carbon dioxide cogeneration unit, the water electrolysis hydrogen production system, the biogas tank, and the biogas purification device are deeply coupled to recycle CO2, H2O, H2, O2, and CH4 to achieve output in multiple energy forms such as cold, heat, electricity, and gas.

[0006] Preferably, the electricity generated by the wind turbines and photovoltaic units is collected and then redistributed. Part of the electricity flows into the water electrolysis hydrogen production system, and the remaining electricity is collected with the electricity produced by the supercritical carbon dioxide cogeneration component and then redistributed. When there is a cooling load requirement, the electricity corresponding to the cooling load is allocated to flow into the electric refrigeration system, and the electric refrigeration system provides the required cooling capacity, and the remaining electricity all flows into the electricity users; among which, the distribution priority of the electricity generated by wind and photovoltaic power is: user electricity load priority > electric system cooling priority > water electrolysis hydrogen production priority.

[0007] Preferably, after receiving H2O as a raw material, the hydropower hydrogen production system produces H2 and O2 when there is electricity supply, and transports them to oxygen storage tanks and hydrogen storage tanks for storage, wherein the oxygen storage tank provides the combustion aid O2 for the supercritical carbon dioxide cogeneration component, and the hydrogen storage tank provides the raw material H2 for the methanation reactor.

[0008] Preferably, rural biomass energy is fermented through a biogas digester at a suitable temperature to produce raw biogas, which is then desulfurized and purified through biogas purification equipment to separate CO2 and CH4, and transported to carbon dioxide storage tanks and natural gas storage centers for storage, wherein the carbon dioxide storage tank provides raw material CO2 for the methanation reactor, and the natural gas storage center provides fuel CH4 for the supercritical carbon dioxide cogeneration component and gas users; after the methanation reaction system receives H2 and CO2 as raw materials, it reacts at the corresponding reaction temperature to produce H2O and CH4, which are respectively sent to a water storage tank and a natural gas storage center; the water storage tank provides raw material H2O for the hydropower hydrogen production system; the CH4 allocated to the supercritical carbon dioxide cogeneration system by the natural gas storage center is compressed by a compressor to form liquid natural gas, which is then sent to the supercritical carbon dioxide cogeneration component.

[0009] Preferably, LNG as fuel and O2 as combustion aid are simultaneously input into the supercritical carbon dioxide cogeneration component to participate in the combustion reaction; when O2 is insufficient, air needs to be input, and O2 is separated through an air separation device for supplement; the supercritical carbon dioxide cogeneration component outputs heat load and electricity load, and the heat load is respectively diverted to heat users and heat storage equipment, and the electricity load is combined with the electricity generated by new energy after meeting the system's electricity consumption; among them, the load ratio priority is: heat load>electricity load; the heat load allocation priority is: heat storage equipment priority>user heat load priority; the H2O and high-concentration CO2 generated by the operation of the supercritical carbon dioxide cogeneration component are transported through different pipelines to the corresponding water storage tanks and carbon dioxide storage tanks, and are recycled as raw materials for the water electrolysis hydrogen production system and the methanation reactor, respectively.

[0010] The present invention also provides a regional multi-energy control method, comprising:

[0011] Obtain real-time price data, load demand data, environmental data, equipment operation data, historical relationship data and basic equipment parameters;

[0012] Based on real-time price data, load demand data, environmental data and equipment operation data, and according to historical relationship data and basic equipment parameters, establish investment and simulation operation functions within the project planning cycle as the objective function;

[0013] Taking the LNG feed rate and the power-to-heat ratio of the supercritical CO2 cogeneration unit as control variables, the objective function is solved to obtain the LNG feed rate and the power-to-heat ratio that should be controlled by the supercritical CO2 cogeneration unit when the system benefits are maximized.

[0014] As a preference, the objective function is:

[0015]

[0016] Among them, Feco is the total benefit of the multi-energy control system, F elec represents the electrical benefit of the multi-energy control system, F heat represents the thermal gain of the multi-energy control system, F cool represents the cooling benefit of the multi-energy control system, F gas represents the natural gas revenue of the multi-energy control system, Indicates the hydrogen benefits of the multi-energy control system, Indicates the oxygen gain of the multi-energy control system, represents the carbon benefits of the multi-energy control system, Represents the water benefits of a multi-energy control system.

[0017] The regional multi-energy system of the present invention uses a methanogenic reactor to deeply couple a supercritical carbon dioxide cogeneration unit, a water electrolysis hydrogen production system, a biogas pool, and a biogas purification device, effectively utilizing different forms of renewable energy such as solar energy, wind energy, and biomass energy, improving the overall energy utilization efficiency of the system, and achieving the goals of energy conservation, emission reduction, and cost reduction. While ensuring the safe operation of the system, it also considers changes in the price of electricity and cold sales, optimizes the distribution of energy through cold storage equipment, and achieves the goal of maximizing benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0019] Figure 1 It is a structural diagram of a regional multi-energy system based on a supercritical carbon dioxide cogeneration unit provided by the present invention;

[0020] Figure 2 This is a structural diagram of a traditional regional multi-energy system based on gas-fired cogeneration units;

[0021] Figure 3 This is a process flow chart of hydrogen production by electrolysis of water according to the present invention;

[0022] Figure 4 It is a flow chart of the Allam cycle-supercritical carbon dioxide cycle cogeneration unit of the present invention;

[0023] Figure 5 It is a process flow chart of the biogas purification device of the present invention;

[0024] Figure 6It is a flowchart of a regional multi-energy system control method based on a supercritical carbon dioxide cogeneration unit provided by the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Embodiment 1:

[0028] The embodiment of the present invention provides a regional multi-energy control system, which uses a methanogenic reactor to deeply couple a supercritical carbon dioxide cogeneration unit, a water electrolysis hydrogen production system, a biogas tank, and a biogas purification device to recycle CO2, H2O, H2, O2, and CH4 to achieve near-zero carbon dioxide emissions. During operation, it makes full use of rural renewable energy to achieve multiple energy outputs such as cold, heat, electricity, and gas.

[0029] like Figure 1 As shown, the regional multi-energy control system of the embodiment of the present invention includes: wind turbines, photovoltaic units, solar thermal units, water electrolysis hydrogen production systems, methanogenic reactors (Synthetic Natural Gas, SNG), supercritical carbon dioxide cogeneration units, electric refrigeration systems (Enclosure Cooler, EC), biogas tanks, biogas purification devices, natural gas storage centers, and several compressors, heat storage equipment, cold storage equipment, hydrogen storage tanks, oxygen storage tanks, carbon dioxide storage tanks, water storage tanks and connecting lines and pipes; the renewable energy of the system mainly comes from wind energy, solar energy, straw, livestock manure and other rural biomass energy. The main loads exported by the system are electrical load, cold load, heat load, and gas load. In addition, when the system cannot meet the external load requirements, the external power grid, external heat network, and external gas network as the backup system will provide energy supplement. Since the cold load can be obtained by converting the electrical load through electric refrigeration, no external cold network is set up in the backup system.

[0030] Furthermore, as new energy generating units, wind turbines and photovoltaic units have installed capacities that are affected by the environment and electricity load, and are designed to be the main bearers of user electricity loads. The amount of electricity generated by new energy is used to meet the user's electricity load needs first, and then to meet the user's cooling load needs. Finally, the remaining electricity is supplied to the water electrolysis hydrogen production system; the solar thermal unit uses a trough-type solar concentrating collector, which is only used as a heating unit to store the surplus heat during the day in a heat storage device for use at night; the water electrolysis hydrogen production system uses a proton exchange membrane (PEM) to electrolyze water to produce hydrogen. When powered on, the electrolyzer is used to electrolyze H2O into H2 and O2. The process flow is as follows: Figure 3 As shown; the methanation reactor uses 3% Ru / Al2O3 (3% Ru by mass on the Al2O3 carrier) as a catalyst, and converts H2 and CO2 into CH4 and H2O at a constant temperature of 300°C and a constant pressure of 100kPa, and separates and purifies them; the supercritical carbon dioxide cogeneration unit uses the Allam cycle-supercritical carbon dioxide cycle cogeneration unit, and its installed capacity is determined by the user's peak and valley period electricity load variation characteristics and the total heat load requirements, and is designed as a peak load unit. Its process flow is as follows Figure 4 As shown; the electric refrigeration system is only used to convert the input electrical load into cold load output. When necessary, the excess power generation is converted into cold energy and transported to the cold storage equipment for storage; the biogas tank is heated by the heat storage equipment, and the raw biogas is output according to the biomass content in the biogas tank; the biogas purification device uses the membrane purification method to separate CH4 and CO2 from the raw biogas containing high concentration of CO2. The process flow is as follows Figure 5 As shown in the figure; the natural gas storage center is the center for storing and transporting CH4. It not only collects CH4 from the methanation reactor and the biogas purification device, but is also responsible for CH4 trading with the external gas network and supplying fuel to the supercritical carbon dioxide cogeneration unit; the compressor pressurizes gaseous CH4 into liquid CH4 (Liquefied Natural Gas, LNG) and provides transportation power; cold storage equipment is used to store cold energy and reasonably absorb excess electric energy to maximize profits; heat storage equipment is used to store and transport heat energy, reasonably allocate heat energy resources and ensure the stable operation of heat equipment; hydrogen storage tanks, oxygen storage tanks, carbon dioxide storage tanks, and water storage tanks are used as storage units, which are used to store and transport H2, O2, CO2 and H2O respectively.

[0031] The multi-energy system of the embodiment of the present invention is a multi-energy system based on a supercritical carbon dioxide cogeneration unit, and consists of four parts: energy source, multi-energy system, load type, and backup system; the energy source is the energy end of the multi-energy system, mainly wind energy, solar energy, straw, livestock manure and other biomass energy that are abundant in rural areas; the load type is the output end of the multi-energy system, mainly electrical load, cooling load, heating load, and gas load; the backup system is the auxiliary supply end of the multi-energy system, mainly external power grid, external heat network, and external gas network.

[0032] The operating principle of the multi-energy system is as follows: the wind turbine and photovoltaic unit convert wind energy and solar energy into electrical energy respectively, and gather at node 1 and redistribute at node 2, wherein the electricity is distributed first to the electricity users, and secondly to the electric refrigeration system used to guarantee the user's cooling load demand. After the user's electricity load and cooling load demand are met, the remaining electricity is distributed to the water electrolysis hydrogen production system; the supercritical carbon dioxide cogeneration unit operates under the optimal LNG feed amount and the optimal electricity-to-heat ratio obtained by the control method. After meeting the system's own electricity consumption, the output electricity is gathered at node 3 with the power generation of the wind turbine and photovoltaic unit, and redistributed at node 4. The user's electricity load is met first, followed by the electric refrigeration system that supplies the user's cooling load. If the electricity cannot be met, it is necessary Purchase electricity from the external power grid. If there is excess electricity, it will be reasonably distributed between sales and cold storage through price comparison to maximize economic benefits. After receiving the electricity allocated by node 4, the electric refrigeration system converts the electricity into cold energy and directly transmits it to the cold users. If the received electricity is excess electricity, the converted cold energy will be transported to the cold storage equipment for storage to alleviate the refrigeration pressure during the peak period of user electricity load demand. After receiving the electricity allocated by node 2, the water electrolysis hydrogen production system will electrolyze the H2O transported from the water storage tank into H2 and O2, and transport them to their respective storage tanks for storage. The H2 in the hydrogen storage tank is used as a raw material and is transported to the methane reactor for the generation of CH4. When the H2 in the hydrogen storage tank exceeds the rated limit, the surplus H2 is transported to the market for sale. The O2 in the oxygen storage tank is used as a combustion aid and is transported to the supercritical carbon dioxide cogeneration unit for auxiliary combustion. When the O2 in the oxygen storage tank exceeds the rated limit, the surplus O2 is transported to the market for sale. The methane reactor receives H2 from the hydrogen storage tank and CO2 from the carbon dioxide storage tank, and reacts chemically at the rated temperature and pressure to output CH4 and H2O, which are transported to the natural gas storage center and water storage tank respectively. When the H2O in the water storage tank exceeds the rated limit, the surplus H2O is transported to the market for sale. When the H2O in the water storage tank is lower than the rated limit and cannot meet the normal operation of the water electrolysis hydrogen production system, H2O needs to be purchased from the market. The solar thermal unit is used as a heating unit to transport the daytime heat to the heat storage device. The heat storage equipment is used to store the heat from the rural biomass and the heat storage equipment, so that this part of energy can be used at night; the heat storage equipment serves as a storage and transportation center for heat energy. It receives heat energy from the solar thermal unit and the supercritical carbon dioxide cogeneration unit, as well as chemical heat from the methane reactor, and redistributes it according to the grade of heat energy to provide heat energy for the methane reactor, the biogas tank, and the biogas purification device to maintain a stable temperature of the equipment; the biogas tank receives heat energy from the rural biomass and the heat storage equipment, ferments at a constant temperature, outputs raw biogas, and transports it to the biogas purification device; the biogas purification device receives heat energy from the heat storage equipment, purifies and separates the received raw biogas, and produces CO2 and CH4, of which CO2 is transported to the carbon dioxide storage tank and CH4 is transported to the natural gas storage center;As a storage and transportation center for CH4, the natural gas storage center not only stores CH4 from the methane reactor and the biogas purification device, but also provides CH4 for gas users and CO2 cogeneration units. If the CH4 in the natural gas storage center cannot meet the transportation needs of gas users and CO2 cogeneration units, it is necessary to purchase CH4 from the external gas network. If the CH4 inventory in the natural gas storage center exceeds the rated limit, it will sell CH4 to the external gas network. The CH4 sent from the natural gas storage center to the CO2 cogeneration unit is compressed by the compressor and then sent to the supercritical CO2 cogeneration unit in the form of LNG as fuel. The supercritical CO2 cogeneration unit receives the LNG compressed by the compressor and the O2 delivered by the oxygen storage tank, burns them, and after meeting its own electricity needs, it transmits electricity and heat to the outside. When the O2 delivered by the oxygen storage tank is not enough to maintain combustion , the cogeneration unit also receives air, and obtains sufficient O2 by separating the air; the H2O and high-concentration CO2 generated by the operation of the supercritical carbon dioxide cogeneration unit are transported through pipelines to the water storage tank and the carbon dioxide storage tank respectively, and are recycled as raw materials for the water electrolysis hydrogen production system and the methane reactor. When the CO2 in the carbon dioxide storage tank exceeds the rated limit, the surplus CO2 is transported to the market for sale; the heat generated by the supercritical carbon dioxide cogeneration unit is transported to node 5 for redistribution, part of which is used to meet the user's heat load demand, and part is sent to the heat storage equipment for storage to meet the heat energy supply to the methane reactor, biogas tank, and biogas purification device. Under normal circumstances, the cogeneration unit gives priority to the supply of heat energy, and the heat energy must be met. In special circumstances, when the heat generated by the cogeneration unit is not enough to meet the user's heat load demand, it is necessary to purchase heat energy from the external heat network. ;

[0033] Figure 2This is the structural diagram of the traditional regional multi-energy system based on gas-fired cogeneration units described in the present invention. The main difference between it and the present invention lies in the utilization method of surplus electricity and the selection of cogeneration units. The utilization method of surplus new energy electricity in the traditional regional multi-energy system is mainly the power to gas (P2G) system. At the same time, due to the lack of cold storage equipment, the surplus electricity of the cogeneration unit is all used for sale, and the cogeneration unit is mainly selected as a gas-fired cogeneration unit. The power to gas system converts CO2 and H2O into CH4 and O2 by utilizing surplus new energy electricity, but since conventional gas-fired cogeneration units rarely perform oxygen-enriched combustion, the O2 obtained by the power to gas system can only be sold to the market. Conventional gas-fired cogeneration units use air as a combustion aid, burn CH4, transmit electricity and heat to the outside, and the exhaust gas after combustion is purified and directly discharged without recycling CO2 and H2O. Therefore, H2O used as a raw material in the power to gas system needs to be purchased from the market. In addition, since the carbon dioxide storage tank only stores CO2 separated by the biogas purification device, the source of CO2 is single and the inventory is small, there is a need to purchase CO2 from the market.

[0034] Compared with the conventional regional multi-energy system based on gas-fired cogeneration units, the system of the present invention has the following advantages:

[0035] 1. Using water electrolysis to produce hydrogen and methanation reactor to couple synthetic natural gas to replace electricity-generated natural gas has higher thermal design possibilities. O2, as one of the products, can be used as a combustion aid for supercritical carbon dioxide cogeneration units, reducing the operating costs of cogeneration units and making the system more economical.

[0036] 2. Use Allam cycle-supercritical carbon dioxide cycle cogeneration unit to replace the traditional gas cogeneration unit. Theoretically, the unit can achieve a thermal efficiency of more than 60%, which is 10%-15% higher than the traditional gas turbine unit. As combustion products, CO2 and H2O are not discharged into the atmosphere and can be recycled. Under normal operation, there is no need to purchase CO2 and H2O from the outside, which is environmentally friendly and reduces the cost of raw materials, which is more conducive to the construction of low-carbon rural areas.

[0037] 3. Introduce cold storage equipment. Through price comparison, when cold storage is more profitable, the surplus output electricity of the cogeneration unit will be converted into cold energy through the electric refrigeration system and stored in the cold storage equipment to achieve higher economic benefits.

[0038] 4. In addition to basic electricity, heat, natural gas, carbon dioxide, and oxygen, the system of the present invention can also output hydrogen and water, thereby increasing the diversity of the system's product output and improving the ability to resist market risks.

[0039] 5. The methanation reactor generates CH4 and H2O through catalytic reaction. The main energy requirement is thermal energy, and the demand for energy grade is low. In addition, the thermal design can be used to recycle chemical heat to improve energy utilization.

[0040] At present, due to the immaturity of supercritical CO2 technology, the maximum single-unit scale is 50MW, which is difficult to apply to ultra-large-scale power generation. Therefore, in the present invention, the supercritical carbon dioxide cogeneration component is not used as the main bearer of the electrical load, but only as a peak-shaving unit. However, with the increasingly stringent environmental protection requirements of the society for energy systems and the continuous improvement of supercritical carbon dioxide cogeneration units, its role in large-scale heating and power generation will become more and more significant.

[0041] Figure 3 This is a process flow chart of the water electrolysis hydrogen production system used in the present invention. Fresh water passes through the water electrolyzer and is decomposed into H2 and O2. H2 and O2 are purified by their respective purifiers to become high-purity gases. Among them, the electrolyzer is a PEM electrolyzer, which avoids the disadvantage of easy permeability of alkaline electrolysis hydrogen production diaphragm gas. The generated H2 has high purity, simple process, high safety, and can adapt to rapidly changing renewable energy power input.

[0042] Figure 4 This is the Allam cycle-supercritical carbon dioxide cycle cogeneration unit flow chart used in the supercritical carbon dioxide cogeneration unit of the present invention. The Allam cycle system is simple, the equipment cost is low, and it has great cycle thermal efficiency. The working fluid CO2 in its cycle is completely closed in the system for recycling, without any greenhouse gas emissions. It is one of the most promising next-generation zero-emission power generation technologies.

[0043] The operation principle of the cogeneration unit is as follows: LNG and the mixed flow of O2 and CO2 pressurized by compressor 2 enter the combustion chamber together for combustion reaction to generate a product flow containing CO2 and H2O, of which the CO2 diverted to the combustion chamber by diverter 3 serves as the combustion chamber coolant; the product flow enters the turbine to expand and do work, and is converted into electrical energy by the generator; in the turbine, according to the heat demand of the methanation reactor, part of the gas is extracted and sent to the heat network 2 through valve regulation, as high-grade thermal energy, stored in the heat storage device for heating the methanation reactor, and then sent to the cooler; the temperature of the combustion chamber reaction product is much higher than the tolerance temperature of the blade material, so the diverter 3 is required to separate a CO2 circulating flow as the turbine coolant; the turbine exhaust enters the regenerator to preheat the circulating flow, and at the same time, O2 from other sources also enters the regenerator to absorb heat. When the O2 from other sources is not enough to support the stable combustion of the combustion chamber, the air separator is started to separate the air after the regenerator. O2 in the gas; after releasing heat in the regenerator, the combustion products still with residual heat are regulated by valves according to the user's heat load demand and the demand for low-grade thermal energy of the heat storage equipment. Part of it is first sent to the heat network 1, and then sent to the cooler after supplying heat to the outside, and part of it is directly sent to the cooler; the water vapor in the combustion products is condensed into liquid in the condenser and output to the outside to obtain high-purity CO2; then, the high-purity CO2 is diverted by the diverter 1, part of the CO2 is captured and output to the outside, and part of the CO2 is compressed to a supercritical state by the compressor 1 to serve as a circulating stream; the circulating stream in the supercritical state is initially compressed by the pump 1 and then divided into two parts by the diverter 2, one part is mixed with O2 through the combiner as an oxidant to assist LNG combustion, and the other part is sent to the combustion chamber and turbine respectively after being diverted by the diverter 3 as a coolant for the combustion chamber and the turbine; the oxidant pressurized by the compressor 2 and the coolant pressurized by the pump 2 are heated in the regenerator and sent to the combustion chamber to control combustion, thereby completing the cycle.

[0044] Figure 5 This is a process flow chart of the biogas purification device used in the present invention. The separation technology used is membrane separation technology. According to the different adsorption capacity, solubility and diffusion rate of CH4 and CO2 on the membrane surface, a certain pressure is applied in the membrane separator to separate the CO2 in the biogas by using the pressure difference on both sides of the membrane. This technology has the advantages of simple process, easy operation, green environmental protection, small footprint, etc., and is more suitable for separating CO2 in small-scale biogas in rural areas.

[0045] The operating principle of the biogas purification device is as follows: the raw biogas output from the biogas tank enters the biogas purification device under conditions close to room temperature and slightly positive pressure. Driven by the fan, the H2S in the biogas is removed through the desulfurization tower to prevent corrosion to subsequent equipment and pipelines; then, it merges with the circulating biogas in the combiner, is compressed to a certain pressure by the compressor, dried and dehydrated by the dryer, and then filtered and deoiled by the filter. After dust removal, the clean gas is heated by the heater and enters the membrane separation system for two-stage membrane separation and purification, and CO2 is separated in the first-stage membrane separation device. CH4 is separated in the second-stage membrane separation device, and the remaining biogas is mixed with the raw biogas in the combiner for recycling. Among them, the purpose of installing a heater in the system is to ensure that the membrane system can operate at the most suitable temperature and achieve the highest separation efficiency, while also maintaining the difference between the gas temperature and the dew point temperature in winter.

[0046] In addition to basic electricity, heat, natural gas, carbon dioxide, and oxygen, the products that can be output by the system of the embodiment of the present invention include hydrogen and water, which are more diverse and have strong resistance to market risks. The system of the embodiment of the present invention replaces the traditional gas cogeneration unit with a supercritical carbon dioxide cogeneration unit, and selects the Allam cycle supercritical carbon dioxide cogeneration unit. Theoretically, the thermal efficiency is 10%-15% higher than that of the traditional gas turbine unit. Its circulating byproducts H2O and CO2 can be recycled in the system. Under normal operation, there is no need to purchase CO2 and H2O from the outside world. It is environmentally friendly and reduces the cost of raw materials, which is more conducive to the construction of low-carbon rural areas. The embodiment of the present invention uses water electrolysis to produce hydrogen and methanation reactors to synthesize natural gas to replace electricity-generated natural gas, which has a higher possibility of thermal design. As one of the products, O2 can be used as a combustion aid for supercritical carbon dioxide cogeneration units, reducing the operating cost of cogeneration units and making the system more economical. In addition, the embodiment of the present invention also adds cold storage equipment to reasonably allocate the surplus power generation between sales and cold storage to achieve the purpose of maximizing economic benefits.

[0047] The embodiments of the present invention are applicable to mountainous rural areas rich in solar energy, wind energy, and biomass, as well as new rural areas with developed agriculture, breeding, or industry. In addition, since the system requires less water resources, it can also provide regional power supply, heating, cooling, and gas supply in arid or semi-arid water-scarce areas, and even water supply during certain periods. In rural areas with developed agriculture and breeding, the biogas system (biogas tank and biogas purification device) in the embodiments of the present invention can be coupled with agriculture and breeding, biogas liquid is used for agricultural irrigation, biogas residue is used for feed regeneration, and crop residues and animal manure can be used as raw materials for the biogas system, reducing costs and improving resource utilization. In isolated rural areas, a seawater desalination system can be added in the embodiments of the present invention to carry out a comprehensive thermal design, and offshore wind power and offshore photovoltaics can be established according to local conditions to increase the power generation of new energy units. In addition, in rural areas with abundant water resources, the embodiments of the present invention also provide a reference for the coupling scheme of hydropower generator sets.

[0048] Embodiment 2:

[0049] An embodiment of the present invention provides a control method for a regional multi-energy system. First, a multi-energy system is established; second, product price data, load demand data, environmental data and equipment operation data are obtained in real time; at the same time, historical relationship data of the equipment during operation and basic parameters of the equipment are collected; then, based on the real-time price data, load demand data, environmental data and equipment operation data, according to the historical relationship data and basic parameters of the equipment, an objective function is established, and the energy and mass balance of each device and the system as a whole and its constraints are set; finally, the objective function is calculated and solved to obtain the optimal LNG feed amount and the optimal electricity-to-heat ratio that the supercritical carbon dioxide cogeneration unit should control.

[0050] Figure 6 This is a flowchart of the regional multi-energy system control method based on supercritical carbon dioxide cogeneration units implemented by the present invention. This flowchart describes the planning and calculation process of a rural multi-energy control system based on supercritical carbon dioxide cogeneration units, covering the complete process from data acquisition, load calculation, working fluid balance calculation to system control and scheduling. Specifically including:

[0051] First, establish a regional multi-energy system based on supercritical carbon dioxide cogeneration units.

[0052] Secondly, obtain price data in real time, including: the unit price of electricity sold to users Unit price of electricity sold to external power grid Unit price of electricity purchased from external power grid The unit heat price for selling heat to users Unit heat price for buying heat from external heat network Unit price of cold sold to users The unit price of natural gas sold to users Unit gas price of natural gas sold from external gas grid Unit gas price for purchasing natural gas from the external gas grid Unit price of hydrogen sold Unit price of oxygen for sale The unit price of selling carbon dioxide Unit price of water sold Unit price of water purchased real time

[0053] Obtain load demand data, including: electrical load demand Heat load demand Cooling load demand Gas load demand

[0054] Real-time acquisition of system runtime environmental data, including: wind speed Solar radiation intensity

[0055] Real-time acquisition of equipment operation data during system operation, including: number of wind turbines in operation n wind , the number of photovoltaic units in operation n lig h t , the number of CSP units in operation n sun , the amount of cold stored in the cold storage equipment The content of hydrogen stored in the hydrogen tank The amount of oxygen stored in the oxygen tank The content of carbon dioxide stored in the carbon dioxide storage tank Methanation reactor temperature The temperature of water produced by the alkylation reactor Temperature of water leaving the methanation reactor Temperature of natural gas produced by methanation reactor Temperature of natural gas leaving the methanation reactor Water content in the water storage tank Biomass content in the digester Actual temperature of the biogas digester Actual temperature of raw biogas before entering the heater of biogas upgrading unit Natural gas content in natural gas storage centers Heat storage equipment heat storage

[0056] At the same time, historical relationship data is collected, including: wind power factor that characterizes the relationship between wind turbine output and wind speed Photovoltaic power factor, which characterizes the relationship between photovoltaic unit output and solar radiation intensity Photothermal power factor, which characterizes the relationship between the heat output of a CSP unit and the intensity of solar radiation The conversion rate that characterizes the ability of a PEM electrolyzer to convert electricity into hydrogen The conversion rate that characterizes the ability of an EC device to convert electrical energy into cooling energy The cold storage efficiency μ represents the cold storage capacity of the cold storage equipment CSE , the heat required to increase the reaction temperature of the methanation reactor by one degree SNG

[0057] h, specific heat capacity of natural gas produced by methanation reactor c g , the specific heat capacity of water produced by the methanation reactor c W , which characterizes the output efficiency of the biogas digester in relation to the biomass Mixed specific heat capacity of biomass in a biogas digester c Bio , the natural gas separation efficiency that characterizes the ability of the biogas upgrading unit to separate natural gas from crude biogas The CO2 separation efficiency, which characterizes the ability of a biogas upgrading unit to separate CO2 from raw biogas Specific heat capacity c of raw biogas before entering the heater in the biogas purification device mix , the circulation rate of raw biogas in the biogas purification device μ mix , the purification rate of crude biogas in the biogas purification device η mix , the unit calorific value of natural gas The power generation efficiency factor K that characterizes the relationship between the power generation efficiency, heat ratio and operating load of the CHP unit 1t , the heat efficiency factor K that characterizes the relationship between the heat efficiency of the CHP unit and the heat ratio and the operating load 2t , the power consumption of the air separator for each unit of oxygen separated Power consumption of the compressor per unit of natural gas compressed Heat storage efficiency of heat storage equipment μ HSE .

[0058] Collect basic parameters of equipment, including: capacity P of a single wind turbine wind , the number of wind turbines installed N wind ; Capacity of a single photovoltaic unit P light , the number of installed photovoltaic units N light ; Capacity of a single CSP unit h sun , the number of installed CSP units N sun ;The maximum amount of electricity that a PEM electrolyzer can withstand The maximum amount of electricity that an electric refrigeration device can withstand The minimum rated limit of the storage capacity of cold storage equipment The maximum rated limit of the storage capacity of cold storage equipment Maximum rated limit of hydrogen content in hydrogen storage tanks Minimum rated limit of hydrogen content in hydrogen storage tanks Optimal quality of hydrogen delivered to the market Maximum rated limit of oxygen content in oxygen tanks Maximum oxygen mass transport capacity of oxygen storage tanks input into cogeneration units Optimal oxygen quality delivery volumes for import into the market Minimum rated limit of oxygen content in oxygen tanks Maximum Rated Limit of CO2 Content in CO2 Tanks Optimal quality of CO2 transported to market Minimum Rated Limits for CO2 Content in CO2 Storage Tanks The mass flow rate of carbon dioxide input when the methanation reactor reaction efficiency is optimal The mass flow rate of hydrogen input when the methanation reactor has the best reaction efficiency The temperature t required for the methanation reactor reaction to proceed sNG ; Maximum rated limit of water content in water storage tank Minimum rated limit of water content in water storage tanks Optimal quality delivery of water to market Maximum capacity of biomass in the digester m Bio，max , the ideal temperature of the biogas digester is t Bio ; The ideal temperature of crude biogas before entering the membrane separator of biogas purification device t BPU ; Maximum rated limit of natural gas content in natural gas storage centers Minimum rated limits for natural gas content in natural gas storage centers Best quality transport volumes sold to external gas grids Maximum transport volume of natural gas input to CHP unit The mass flow rate of natural gas required at rated load of CHP unit Minimum heat storage capacity H of heat storage equipment NSE，min .

[0059] Then, based on the real-time price data, load demand data, environmental data and equipment operation data, according to the historical relationship data and the basic parameters of the equipment, the investment and simulation operation functions within the entire project planning cycle are established as the objective function.

[0060] The objective function is as follows:

[0061]

[0062] Among them, F eco is the total benefit of the multi-energy control system, F elec represents the electrical benefit of the multi-energy control system, Fheat represents the thermal gain of the multi-energy control system, F cool represents the cooling benefit of the multi-energy control system, F gas represents the natural gas revenue of the multi-energy control system, Indicates the hydrogen benefits of the multi-energy control system, Indicates the oxygen gain of the multi-energy control system, represents the carbon benefits of the multi-energy control system, Represents the water benefits of a multi-energy control system.

[0063] The calculation formula for electricity, heat, cold, natural gas, hydrogen, oxygen and carbon benefits is as follows:

[0064]

[0065] in, represents the unit electricity price sold by the multi-energy system to users at time t, represents the user's electricity load demand at time t, represents the unit price of electricity sold by the multi-energy system to the external power grid at time t, represents the amount of electricity sold by the multi-energy system to the external power grid at time t, represents the unit price of electricity purchased by the multi-energy system from the external power grid at time t, It represents the amount of electricity purchased by the multi-energy system from the external power grid at time t; represents the unit heat price sold by the multi-energy system to users at time t, represents the heat load demand of the user at time t, represents the unit heat price of the multi-energy system purchasing heat from the external heat network at time t, represents the amount of heat purchased by the multi-energy system from the external heating network at time t; represents the unit cooling price of the multi-energy system selling cooling to users at time t, represents the cooling load demand of the user at time t; represents the unit gas price of natural gas sold by the multi-energy system to users at time t, represents the gas load demand of the user at time t, represents the unit gas price of natural gas sold by the multi-energy system from the external gas grid at time t, represents the gas volume sold by the multi-energy system to the external gas grid at time t, represents the unit gas price of natural gas purchased by the multi-energy system from the external gas grid at time t, It represents the gas volume purchased by the multi-energy system from the external gas grid at time t; represents the unit hydrogen price of hydrogen sold by the multi-energy system at time t, represents the amount of hydrogen sold to the market by the multi-energy system at time t; represents the unit oxygen price of oxygen sold by the multi-energy system at time t, represents the amount of oxygen sold to the market by the multi-energy system at time t; represents the unit carbon price of carbon dioxide sold by the multi-energy system at time t, represents the amount of carbon sold to the market by the multi-energy system at time t; represents the unit water price of water sold by the multi-energy system at time t, represents the amount of water sold to the market by the multi-energy system at time t, represents the unit water price of the multi-energy system at time t, It represents the amount of water purchased by the multi-energy system from the market at time t.

[0066] In order to solve the objective function, it is necessary to set the energy and mass balance of each device and its constraints, and establish the balance equation of the entire system to ensure the safe operation of the multi-energy system of the present invention.

[0067] Among them, the equipment that needs to set balance and its constraints include: wind turbines, photovoltaic units, solar thermal units, water electrolysis hydrogen production systems, electric refrigeration devices, cold storage equipment, hydrogen storage tanks, oxygen storage tanks, carbon dioxide gas storage tanks, methanation reactors, water storage tanks, biogas pools, biogas purification devices, natural gas storage centers, supercritical carbon dioxide cogeneration units, and heat storage equipment. The balance equations of the entire system include: electrical power balance equation, thermal power balance equation, cold power balance equation, and gas volume balance equation.

[0068] Balance and constraints of wind turbines:

[0069]

[0070] 0≤n wind ≤N wind

[0071] in, represents the output of wind turbines in the multi-energy system at time t, It represents the wind power factor at time t, and its magnitude is determined by the wind speed at time t. Through historical relationship matching, P wind Represents the capacity of a single wind turbine, n wind Indicates the number of wind turbines in operation; N wind Indicates the number of installed wind turbines.

[0072] The balance and constraints of photovoltaic units:

[0073]

[0074] 0≤n light ≤N light

[0075] in, represents the output of the photovoltaic unit of the multi-energy system at time t, It represents the photovoltaic power factor at time t, and its magnitude is determined by the solar radiation intensity at time t. Through historical relationship matching, P lig h t Represents the capacity of a single photovoltaic unit, n light Indicates the number of operating photovoltaic units; N light Indicates the number of installed PV panels.

[0076] Balance and constraints of CSP units:

[0077]

[0078] 0≤n sun ≤N sun

[0079] in, represents the heat output of the CSP unit in the multi-energy system at time t, It represents the light-heat power factor at time t, and its magnitude is determined by the solar radiation intensity at time t. Through historical relationship matching, h sun Represents the capacity of a single CSP unit, n sun Indicates the number of CSP units in operation; N sun Indicates the number of installed CSP units.

[0080] The balance and constraints of the water electrolysis hydrogen production system equipment:

[0081]

[0082] in, represents the electric power input into the PEM electrolyzer at time t, Indicates the efficiency of the PEM electrolyzer in converting electrical energy into hydrogen; represents the mass flow rate of hydrogen produced by the PEM electrolyzer at time t, represents the mass flow rate of oxygen produced by the PEM electrolyzer at time t, It represents the mass flow rate of water required for the PEM electrolyzer to electrolyze water to produce hydrogen at time t; Indicates the maximum amount of electricity that a PEM electrolyzer can withstand.

[0083] also, The size of is subject to the following constraints:

[0084]

[0085] in, represents the amount of new energy electricity allocated to the electric refrigeration device at time t, Indicates the cold energy conversion rate of the EC device.

[0086] Balance and constraints of electric refrigeration equipment:

[0087]

[0088] in, It represents the amount of electricity that the CHP unit allocates to the electric refrigeration device for direct cooling at time t. It represents the amount of electricity that the CHP unit allocates to the electric refrigeration device for indirect cooling at time t; It represents the amount of electricity purchased from the external power grid at time t that is allocated to the electric refrigeration device for direct cooling; It represents the cooling capacity directly allocated to users by the electric refrigeration device at time t; It represents the cooling capacity allocated by the electric refrigeration device to the cold storage device at time t; Indicates the maximum amount of electricity that an electric refrigeration unit can withstand.

[0089] in, The relationship is as follows:

[0090]

[0091] in, It indicates the amount of electricity that the CHP unit outputs to the outside after supplying internal electricity at time t. It represents the amount of electricity distributed by the CHP unit to the user at time t; It indicates the amount of electricity purchased from the external power grid allocated to users at time t.

[0092] when hour:

[0093]

[0094] Among them, μ CSE Indicates the cold storage efficiency of the cold storage equipment, represents the amount of cold stored in the cold storage device at time t, Indicates the minimum rated limit of the cold storage capacity in the cold storage equipment.

[0095] when hour:

[0096]

[0097] when hour:

[0098]

[0099] when hour:

[0100]

[0101] when hour:

[0102]

[0103] when hour:

[0104]

[0105] when hour:

[0106]

[0107] when hour:

[0108]

[0109] when hour:

[0110]

[0111] when hour:

[0112]

[0113] when hour:

[0114]

[0115] in, Indicates the maximum rated limit of the cold storage capacity in the cold storage equipment.

[0116] when hour:

[0117]

[0118] when hour:

[0119]

[0120] when hour:

[0121]

[0122] when hour:

[0123]

[0124] when hour:

[0125]

[0126] when hour:

[0127]

[0128] when hour:

[0129]

[0130] Balance and constraints of cold storage equipment (CSE):

[0131]

[0132] in, It represents the cooling capacity provided by the cold storage equipment to the user at time t. Indicates the mass change of hydrogen in the hydrogen storage tank at time t.

[0133] when hour:

[0134]

[0135] when hour:

[0136]

[0137] when hour:

[0138]

[0139] Balance and constraints of hydrogen tanks (HT):

[0140]

[0141] in, represents the mass flow rate of hydrogen from the hydrogen storage tank into the methanation reactor at time t, Indicates the mass change of hydrogen in the hydrogen storage tank at time t.

[0142] when hour:

[0143]

[0144] in, Indicates the content of hydrogen stored in the hydrogen storage tank at time t, Indicates the maximum rated limit of hydrogen content in a hydrogen storage tank; represents the optimal mass transport amount of hydrogen input to the methanation reactor, that is, the mass flow rate of hydrogen input when the reaction efficiency of the methanation reactor is optimal, which is a specific constant; It represents the optimal quality transport volume of hydrogen imported into the market, which is a specific constant, and its size is determined by the transport equipment; represents the mass flow rate of carbon dioxide from the carbon dioxide gas storage tank into the methanation reactor at time t, The optimal mass transport volume of carbon dioxide input to the methanation reactor, that is, the mass flow rate of carbon dioxide input when the reaction efficiency of the methanation reactor is optimal, is a specific constant.

[0145] when hour:

[0146]

[0147] when hour:

[0148]

[0149] in, Indicates the minimum rated limit of hydrogen content in a hydrogen storage tank.

[0150] when hour:

[0151]

[0152] when hour:

[0153]

[0154] Balance and constraints of oxygen tanks (OT):

[0155]

[0156] in, It represents the oxygen mass flow rate from the oxygen storage tank to the cogeneration unit at time t, Represents the mass change of oxygen in the oxygen storage tank at time t.

[0157] when hour:

[0158]

[0159] in, It indicates the oxygen content in the oxygen storage tank at time t. Indicates the maximum rated limit of oxygen content in the oxygen storage tank; represents the demand for natural gas from the cogeneration unit at time t; It indicates the maximum mass of oxygen transported from the oxygen storage tank to the cogeneration unit, which is a specific constant, and its size is determined by the transport equipment; It represents the optimal quality of oxygen transported into the market. It is a specific constant whose size is determined by the transport equipment.

[0160] when hour:

[0161]

[0162] in, Indicates the minimum rated limit of the oxygen content in the oxygen storage tank.

[0163] when hour:

[0164]

[0165] Balance and constraints of carbon dioxide tanks (CT):

[0166]

[0167] in, It represents the mass flow rate of carbon dioxide from the biogas purification device to the carbon dioxide storage tank at time t, represents the mass flow rate of carbon dioxide from the combined heat and power unit to the carbon dioxide gas storage tank at time t, Indicates the mass change of carbon dioxide in the carbon dioxide gas storage tank at time t.

[0168] when hour:

[0169]

[0170] in, It represents the content of carbon dioxide stored in the carbon dioxide storage tank at time t, Indicates the maximum rated limit of the carbon dioxide content in the carbon dioxide storage tank; It represents the optimal mass transport volume of carbon dioxide to be imported into the market. It is a specific constant whose size is determined by the transportation equipment.

[0171] when hour:

[0172]

[0173] when hour:

[0174]

[0175] in, Indicates the minimum rated limit of the carbon dioxide content in a carbon dioxide storage tank.

[0176] when hour:

[0177]

[0178] when hour:

[0179]

[0180] The equilibrium and constraints of the methanation reactor:

[0181]

[0182] in, represents the mass flow rate of water output from the methanogenation reactor at time t, It represents the mass flow rate of natural gas output from the methanation reactor at time t.

[0183] The heat balance equation for safe operation of the methanation reactor is:

[0184]

[0185] in, represents the heat required by the heat storage device to be transferred by the methanogenation reactor at time t, h SNG It represents the heat required to increase the reaction temperature of the methanogenation reactor by one degree, t SNG represents the temperature required for the methanation reactor reaction to proceed, represents the temperature of the methanation reactor at time t; represents the heat c transferred from the methanogenation reactor to the heat storage device at time t W represents the specific heat capacity of water, c g is the specific heat capacity of natural gas, represents the temperature at which water is produced by the reaction, represents the temperature of the water leaving the methanogenation reactor, The temperature at which the reaction produces natural gas, Indicates the temperature of the natural gas when it leaves the methanation reactor.

[0186] Water Tanks Balance and Constraints:

[0187]

[0188] in, represents the mass flow rate of water input into the water storage tank by the cogeneration unit at time t, Represents the change in mass of water in the water tank at time t.

[0189] when hour:

[0190]

[0191] in, represents the water content in the water tank at time t, Indicates the maximum rated limit of water content in a water storage tank; It represents the optimum quality transport volume of water delivered to the market, and is a specific constant whose size is determined by the transport equipment.

[0192] when hour:

[0193]

[0194] in, Indicates the minimum rated limit of water content in a water storage tank.

[0195] when hour:

[0196]

[0197] The balance and constraints of the biogas station (BS):

[0198]

[0199] in, It represents the mass flow rate of raw biogas produced by the biogas digester at time t, represents the content of biomass in the biogas digester at time t, Indicates the efficiency of producing raw biogas from biomass in the biogas digester; m Bio，max Indicates the maximum capacity of biomass in the digester.

[0200] The heat balance equation for safe operation of the biogas digester is:

[0201]

[0202] in, represents the heat required by the heat storage equipment to be transferred by the biogas digester at time t, c Bio represents the mixing specific heat capacity of biomass in the digester, t Bio Indicates the ideal temperature of the biogas digester, Indicates the actual temperature of the biogas digester at time t.

[0203] Balance and constraints of biogas purification unit (BPU):

[0204]

[0205] in, It represents the mass flow rate of natural gas separated by the biogas purification device at time t, It indicates the efficiency of the biogas upgrading plant in separating natural gas from raw biogas; represents the mass flow rate of carbon dioxide separated by the biogas purification device at time t, Indicates the efficiency of the biogas upgrading plant in separating carbon dioxide from raw biogas.

[0206] The heat balance equation for safe operation of biogas purification device is:

[0207]

[0208] in, Indicates the heat required by the heat storage equipment for the biogas purification device at time t, represents the mass flow rate of raw biogas before entering the heater in the biogas purification device, c mix represents the specific heat capacity of the raw biogas before entering the heater in the biogas purification device, t BPU Indicates the ideal temperature of raw biogas before entering the membrane separator. Indicates the actual temperature of the raw biogas before entering the heater at time t; μ mix represents the circulation rate of raw biogas, η mix Indicates the purification rate of raw biogas.

[0209] Balance and constraints of Natural gas Storage Center (NSC):

[0210]

[0211] in, Represents the mass change of natural gas in the natural gas storage center at time t.

[0212] when hour:

[0213]

[0214] in, represents the natural gas content in the natural gas storage center at time t, Indicates the maximum rated limit of natural gas content in a natural gas storage center; It represents the optimal quality transport volume sold to the external gas network. It is a specific constant whose size is determined by the transportation equipment.

[0215] when hour:

[0216]

[0217] in, Indicates the minimum rated limit of natural gas content in a natural gas storage center

[0218] when hour:

[0219]

[0220] when hour:

[0221]

[0222] Balance and constraints of supercritical carbon dioxide cogeneration unit:

[0223]

[0224] in, They represent the power generation and heat generation of the CHP unit at time t respectively; They represent the efficiency of power generation and heat generation of the CHP unit respectively; Indicates the unit calorific value of natural gas; Indicates the maximum transport volume of natural gas input to the CHP unit;

[0225] The efficiency calculation formula for power generation and heat generation of supercritical carbon dioxide cogeneration unit is as follows:

[0226]

[0227] Among them, K 1t , K 2t They represent the efficiency factors of power generation and heat production of the CHP unit at time t, θ t represents the electric-to-heat ratio of the CHP unit at time t, A t represents the operating load of the CHP unit at time t, Indicates the mass flow rate of natural gas required at rated load of the CHP unit.

[0228] The mass balance and power balance of the CHP unit are as follows:

[0229]

[0230] in, represents the oxygen mass flow rate required for the operation of the supercritical carbon dioxide cogeneration unit at time t, represents the mass flow rate of oxygen separated by the air separator at time t, It represents the mass flow rate of air required by the supercritical carbon dioxide cogeneration unit at time t; represents the power consumption of the air separator in the supercritical carbon dioxide cogeneration unit at time t, represents the power consumption of the compressor at time t, Indicates the power consumption of the air separator for each unit of oxygen separated. Indicates the power consumption of the compressor per unit of natural gas compressed.

[0231] The balance of heat storage equipment (HSE) and its constraints (only considering the amount of heat energy, not the quality of heat energy, and the heat storage capacity is designed to not reach the upper limit of the heat storage equipment):

[0232]

[0233] in, represents the heat input from the CHP unit to the heat storage device at time t, μ HSE represents the heat storage efficiency of the heat storage device, Represents the change in thermal energy of the heat storage device at time t.

[0234] when hour:

[0235]

[0236] in, represents the amount of heat stored in the heat storage device at time t, H NSE , min Indicates the minimum heat storage capacity of the heat storage device.

[0237] when hour:

[0238]

[0239] when hour:

[0240]

[0241] Electric power balance in multi-energy systems:

[0242]

[0243] Gas balance in multi-energy systems:

[0244]

[0245] Thermal power balance of multi-energy systems:

[0246]

[0247] in, Indicates the amount of heat delivered by the CHP unit to heat users.

[0248] Cold power balance of multi-energy systems:

[0249]

[0250] Based on the energy and mass balance of each device and the entire system and their constraints, the natural gas feed rate and the power-to-heat ratio of the supercritical carbon dioxide cogeneration unit are taken as control variables, and the objective function is calculated and solved. The optimal LNG feed rate and the optimal power-to-heat ratio that should be controlled by the supercritical carbon dioxide cogeneration unit can be obtained.

[0251] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A regional multi-energy control system, characterized in that: include: Wind turbines, photovoltaic units, solar thermal units, water electrolysis hydrogen production systems, methanation reactors, supercritical carbon dioxide cogeneration units, electric refrigeration systems, biogas tanks, biogas purification devices, and natural gas storage centers; among them, through the methanation reactor, the supercritical carbon dioxide cogeneration units, water electrolysis hydrogen production systems, biogas tanks, and biogas purification devices are deeply coupled to recycle CO2, H2O, H2, O2, and CH4 to achieve output in multiple energy forms such as cold, heat, electricity, and gas.

2. The regional multi-energy control system according to claim 1, characterized in that: After the electricity generated by wind turbines and photovoltaic units is collected, it is redistributed. Part of the electricity flows into the water electrolysis hydrogen production system, and the remaining electricity is collected with the electricity produced by the supercritical carbon dioxide cogeneration component and then redistributed. When there is a cooling load requirement, the electricity corresponding to the cooling load is allocated to the electric refrigeration system, which provides the required cooling capacity, and the remaining electricity flows into the electricity users. Among them, the distribution priority of the electricity generated by wind and photovoltaic power is: user electricity load priority > electric system cooling priority > water electrolysis hydrogen production priority.

3. The regional multi-energy control system according to claim 2, characterized in that: After receiving H2O as raw material, the hydropower hydrogen production system produces H2 and O2 when there is electricity supply, and transports them to oxygen storage tanks and hydrogen storage tanks for storage. The oxygen storage tank provides the combustion aid O2 for the supercritical carbon dioxide cogeneration component, and the hydrogen storage tank provides the raw material H2 for the methanation reactor.

4. The regional multi-energy control system according to claim 3, characterized in that: Rural biomass energy is fermented through a biogas digester at a suitable temperature to produce raw biogas, which is then desulfurized and purified through biogas purification equipment to separate CO2 and CH4, and transported to carbon dioxide storage tanks and natural gas storage centers for storage. The carbon dioxide storage tank provides raw material CO2 for the methanation reactor, and the natural gas storage center provides fuel CH4 for the supercritical carbon dioxide cogeneration component and gas users; after the methanation reaction system receives H2 and CO2 as raw materials, it reacts at the corresponding reaction temperature to produce H2O and CH4, which are respectively sent to the water storage tank and the natural gas storage center; the water storage tank provides raw material H2O for the hydropower hydrogen production system; the CH4 allocated to the supercritical carbon dioxide cogeneration system by the natural gas storage center is compressed by a compressor to form liquid natural gas, and then sent to the supercritical carbon dioxide cogeneration component.

5. The regional multi-energy control system according to claim 4, characterized in that: LNG as fuel and O2 as combustion aid are simultaneously input into the supercritical carbon dioxide cogeneration component to participate in the combustion reaction; when O2 is insufficient, air needs to be input and O2 is separated through an air separation device for supplement; the supercritical carbon dioxide cogeneration component outputs heat load and electricity load, and the heat load is respectively diverted to heat users and heat storage equipment, and the electricity load is combined with the electricity generated by new energy after meeting the system's electricity consumption; among them, the load ratio priority is: heat load>electricity load; the heat load allocation priority is: heat storage equipment priority>user heat load priority; the H2O and high-concentration CO2 generated by the operation of the supercritical carbon dioxide cogeneration component are transported through different pipelines to the corresponding water storage tanks and carbon dioxide storage tanks, and are recycled as raw materials for the water electrolysis hydrogen production system and the methanation reactor respectively.

6. A regional multi-energy control method, characterized in that: include: Obtain real-time price data, load demand data, environmental data, equipment operation data, historical relationship data and basic equipment parameters; Based on real-time price data, load demand data, environmental data and equipment operation data, and according to historical relationship data and basic equipment parameters, establish investment and simulation operation functions within the project planning cycle as the objective function; Taking the LNG feed rate and the power-to-heat ratio of the supercritical CO2 cogeneration unit as control variables, the objective function is solved to obtain the LNG feed rate and the power-to-heat ratio that should be controlled by the supercritical CO2 cogeneration unit when the system benefits are maximized.

7. The regional multi-energy control method according to claim 6, characterized in that: The objective function is: Among them, F eco is the total benefit of the multi-energy control system, F elec represents the electrical benefit of the multi-energy control system, F heat represents the thermal gain of the multi-energy control system, F cool represents the cooling benefit of the multi-energy control system, F gas represents the natural gas revenue of the multi-energy control system, Indicates the hydrogen benefits of the multi-energy control system, Indicates the oxygen gain of the multi-energy control system, represents the carbon benefits of the multi-energy control system, Represents the water benefits of a multi-energy control system.

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