Wind-light-hydrogen comprehensive energy system low-carbon optimization operation method considering fuel cell waste heat recovery

Abstract

The invention relates to a wind-light-hydrogen comprehensive energy system optimization operation method considering fuel cell waste heat recovery, and the method mainly comprises the following steps: 1, constructing a high-temperature solid oxide fuel cell waste heat recovery model, and analyzing the mechanism of the fuel cell waste heat recovery for promoting wind power photovoltaic absorption and reducing carbon emission; step 2, establishing a wind-light-hydrogen comprehensive energy system model architecture considering fuel cell waste heat recovery on the basis of the step 1; and step 3, establishing a wind-light-hydrogen comprehensive energy system operation optimization model considering fuel cell waste heat recovery on the basis of the step 1 and the step 2. The lowest comprehensive cost of the system is taken as a target, the energy purchase cost, the stepped carbon transaction cost and the wind and light abandoning punishment cost of the system are fully considered, and the low-carbon economical operation of the system is realized. In consideration of certain advantages of fuel cell waste heat recovery in three aspects of system operation cost, carbon emission reduction and new energy consumption, a feasible reference can be provided for clean low-carbon transformation of a comprehensive energy system.

Description

Technical Field

[0001] This invention patent belongs to the technical field of new energy and electric power, and particularly relates to an optimized operation method for a wind-solar-hydrogen integrated energy system considering the waste heat recovery of fuel cells, providing an effective method for realizing the low-carbon operation of the integrated energy system. Background Technique

[0002] The integrated energy system (IES) has the operating characteristics of multi-energy complementarity and multi-energy cooperation. As an important hub of multiple energy subsystems, the integrated energy system realizes energy interconnection and optimized scheduling by integrating various energy resources such as electricity, gas, and heat energy, thereby improving the coordination ability of energy supply and demand, which is of great significance for reducing the carbon level in the energy industry. Currently, the research on low-carbon energy has become a hot topic. As a clean secondary energy source, hydrogen energy has the advantages of zero carbon emissions and being applicable to both long-term and short-term operations. With the continuous development of hydrogen energy technology, hydrogen energy load has become a common load in IES, and hydrogen energy plays an increasingly important role in the application of IES. Solid oxide fuel cells (SOFC) have the advantages of high power generation efficiency, strong fuel adaptability, and recoverable high-temperature waste heat, can realize the thermal coupling in hydrogen-electric conversion, and have broad application prospects in the field of combined heat and power supply.

[0003] To further promote the consumption and utilization of renewable energy such as wind, solar, and hydrogen in IES and reduce carbon emissions, and considering that the waste heat recovery of high-temperature solid oxide fuel cells is less considered and has great economic value, a low-carbon optimized operation method for a wind-solar-hydrogen integrated energy system considering the waste heat recovery of fuel cells is proposed to realize the consumption of renewable resources such as wind and solar and the low-carbon operation of the integrated energy system.

[0004] CN117172406A discloses a low-carbon optimization method for a regional integrated energy system based on tscTFCSNPS path selection, which includes the following steps: constructing a target regional integrated energy system; selecting an energy supply path from the target regional integrated energy system through a pulsed neural membrane system; discarding the energy supply paths that do not meet the constraint conditions from the selected energy supply paths; constructing an objective function based on the operating cost and carbon dioxide emissions of the target regional energy; solving the objective function through a genetic algorithm to obtain the optimal energy supply plan for each energy supply path; selecting the optimal energy supply plan from the optimal energy supply plans of each energy supply path to complete the low-carbon optimization of the regional integrated energy system. This invention solves the problems that the existing technology does not consider the diversity of the combination of energy supply equipment when supplying energy to the load in RIES and does not perform effective low-carbon optimization.

[0005] It realizes low-carbon optimization through pulse neural membrane systems, etc., and is not suitable for low-carbon optimization of wind-solar-hydrogen integrated energy systems. Summary of the Invention

[0006] Aiming at the above situation, this invention patent proposes a low-carbon optimal operation method for wind-solar-hydrogen integrated energy systems considering the waste heat recovery of fuel cells. By introducing an electrolytic water hydrogen production device, methanation reaction, and high-temperature solid oxide fuel cell, it realizes the consumption of renewable energy such as wind, solar, and hydrogen and reduces carbon emissions within the system. A waste heat recovery model of high-temperature solid oxide fuel cells is constructed. Secondly, a stepped carbon trading model is introduced. Then, an operation model is constructed with the goal of minimizing the sum of the system's energy purchase cost, carbon trading cost, and penalty cost for abandoned wind and solar power. On the premise of meeting the multi-energy load demand, the impact of fuel cell waste heat recovery on system emissions reduction is analyzed.

[0007] The above technical problems of this invention are mainly achieved through the following technical solutions: A low-carbon optimal operation method for wind-solar-hydrogen integrated energy systems considering the waste heat recovery of fuel cells, characterized by including the following steps: Step 1: Construct a waste heat recovery model of high-temperature solid oxide fuel cells, and analyze the mechanism of fuel cell waste heat recovery to promote the consumption of wind power and photovoltaic power and reduce carbon emissions. The output model of high-temperature solid oxide fuel cells can be expressed as: In the formula: η SOFC are the hydrogen consumption power, power generation power, heat generation power, and power generation efficiency of the fuel cell respectively; P SOFC,max is the maximum value of the power generation power; ΔP SOFC,max ; ΔP SOFC,min are the maximum and minimum ramp powers respectively.

[0008] The waste heat recovery device can absorb a part of the unreacted fuel in the power generation unit of the high-temperature solid oxide fuel cell for heating, as follows: In the formula: η WHB are the output heat power and recovery efficiency of the waste heat recovery device respectively; P WHB,max is the maximum output heat power of the waste heat recovery device; ΔP WHB,max 、ΔP WHB,min are the maximum and minimum ramp powers respectively.

[0009] During the periods when wind and solar energy are abundant, recovering the waste heat of fuel cells can effectively reduce the output of combined heat and power (CHP) units and gas boilers. This not only reduces the power supply of the CHP system but also releases more space to accommodate wind and photovoltaic energy, thereby effectively improving the utilization rate of renewable energy. In addition, by recovering the waste heat of fuel cells, carbon emissions can be reduced, making it more environmentally friendly. Therefore, considering the recovery of fuel cell waste heat during periods of abundant wind and solar energy has a positive impact on the operation of the energy system.

[0010] Step 2: Establish a model architecture for a wind-solar-hydrogen integrated energy system considering fuel cell waste heat recovery. The output power model of combined heat and power (CHP) is as follows: In the formula: is the input natural gas power of CHP at time t. are the output electric power and heat power of CHP at time t respectively; δ chp are the electric efficiency and heat-electric ratio of CHP respectively; is the maximum value of the input natural gas power; are the maximum and minimum ramp powers respectively. The output power model of gas boilers (GB) is as follows: In the formula: is the input natural gas power of GB at time t; is the output heat power of GB at time t; is the heat efficiency of GB; is the maximum value of the input natural gas power; are the maximum and minimum ramp powers respectively.

[0011] The models of hydrogen production by electrolysis of water (Electrolyzer, EL) and methanation reaction (Methanation reaction, MR) are as follows: In the formula: η EL are the input electric power, output hydrogen power and hydrogen production efficiency respectively; is the maximum value of the input electric power; are the maximum and minimum ramp powers respectively; is the hydrogen power input to MR; P MR,g (t) is the output gas power of MR; ηMR is the gas production efficiency of MR; are the maximum and minimum values of the input hydrogen power.

[0012] The energy storage model is as follows: In the formula: n represents the energy type, n ∈ {e, h, H2}; E n (t) is the stored energy of the nth energy storage device in the t time period; ε is the self-loss rate of the energy storage device; P n,in (t), P n,out (t) are the charging and discharging powers of the nth energy storage device in the t time period respectively; η n,in , η n,out are the charging and discharging efficiencies of the nth energy storage device respectively; are the upper and lower limits of the capacity of the nth energy storage device; are all 0-1 logical variables, indicating the charging and discharging states of the nth energy storage device in the t time period; represent the maximum charging and discharging powers of the nth energy storage device respectively; T is the scheduling period.

[0013] Step 3: Establish an operation optimization model of a wind-solar-hydrogen integrated energy system considering the waste heat recovery of fuel cells. The objective function is to minimize the total system cost, that is, to minimize the sum of the energy purchase cost, the stepped carbon trading cost, and the penalty cost for wind and light curtailment, so as to achieve the low-carbon economic operation of the system; The objective function in the above Step 3 is: In the formula: C buy is the energy purchase cost; is the stepped carbon trading cost; C w is the penalty cost for wind and light curtailment. The energy purchase cost is: In the formula: α t , β t represent the electricity price and gas price in the t time period respectively; P g,buy (t) is the gas purchase volume in the t time period; P e,buy (t) is the electricity purchase volume in the t time period.

[0014] The penalty cost for wind and light curtailment is: In the formula: r w is the penalty coefficient for wind and light curtailment; is the upper limit of the wind power and photovoltaic power output in the t time period, that is, the predicted value of wind power and photovoltaic power; P WT(t), P PV (t) are the wind power and photovoltaic power outputs during the time period t, respectively.

[0015] The stepped carbon trading cost is: In the formula: is the stepped carbon trading cost; ψ is the base price of carbon trading; μ is the price growth rate; l is the length of the unit carbon emission interval; E IES,t is the quantity of carbon emission rights quota.

[0016] The quantity of carbon emission rights quota is: In the formula: E IES,ι is the quantity of carbon emission rights quota purchased in the carbon trading market; E IES is the actual carbon emission of the system; is the carbon emission rights quota of the system.

[0017] The carbon emission rights quota model is: In the formula: are the carbon emission rights quotas of the superior power purchase, CHP, and GB, respectively; α e , α g are the carbon emission rights quotas for the unit power consumption of the coal-fired unit and the unit natural gas consumption of the natural gas-fired unit, respectively; P e,buy (t) is the quantity of power purchased from the superior grid at time t; T is the dispatching period.

[0018] The actual carbon emission model is: In the formula: E e,buy , E CHP , E GB are the actual carbon emissions of the power purchased from the external grid, CHP, and gas boiler, respectively; E P2G is the amount of carbon dioxide consumed in the production of natural gas by the P2G equipment; δ e , δ h are the actual carbon emissions per unit of electric power produced by the coal-fired unit and the actual carbon emissions per unit of thermal power produced by the natural gas-fired unit, respectively; C P2G (t) represents the amount of carbon dioxide consumed by the power-to-gas equipment during the time period t.

[0019] In step 3 above, constraints such as wind-solar power output constraints, energy purchase constraints, and power balance are considered. The wind-solar power output constraints are as follows: External grid power purchase constraint: In the formula: is the maximum value of electricity purchased from the external power grid.

[0020] External gas network gas purchase constraint: In the formula: is the maximum value of gas purchased from the external power grid.

[0021] The electric power balance constraint is as follows: In the formula: are the charging and discharging powers of the energy storage device in the t time period, respectively; is the electric load at time t.

[0022] The thermal power balance constraint is as follows: In the formula: are the heat storage and heat release powers of the heat storage device in the t time period, respectively; is the heat load at time t.

[0023] The gas power balance constraint is as follows: The hydrogen power balance constraint is as follows: In the formula: respectively represent the hydrogen storage and hydrogen release powers of the hydrogen storage device in the t time period; is the hydrogen load.

[0024] Regarding the problems of the accommodation of renewable energy such as wind-solar-hydrogen and the high carbon emissions of traditional integrated energy systems, the present invention realizes the accommodation of renewable energy and the low-carbon operation of the system by introducing an electrolytic water hydrogen production device and considering the waste heat recovery of fuel cells. Considering the certain advantages of waste heat recovery of fuel cells in terms of system operation cost, carbon emission reduction, and new energy accommodation, it can provide a feasible reference for the clean and low-carbon transformation of integrated energy systems. Description of the Drawings

[0025] Figure 1 Mechanism diagram of waste heat recovery of fuel cells promoting the accommodation of wind power and photovoltaic power and reducing carbon emissions.

[0026] Figure 2 Model structure block diagram of a wind-solar-hydrogen integrated energy system considering waste heat recovery of fuel cells.

[0027] Figure 3 Wind power, photovoltaic power, and load prediction diagram.

[0028] Figure 4This is the principle flow block diagram of the present invention. Specific embodiments

[0029] The technical solution of the present invention will be further specifically described below with reference to the accompanying drawings.

[0030] The present invention relates to a method for low-carbon optimal operation of an integrated energy system, and particularly to a method for low-carbon optimal operation of a wind-solar-hydrogen integrated energy system. This method realizes the production of hydrogen energy and the consumption of renewable energy such as wind and solar by introducing an electrolytic water hydrogen production device and a high-temperature solid oxide fuel cell. At the same time, considering the characteristic that the waste heat of the high-temperature solid oxide fuel cell can be recycled, the low-carbon economic operation of the integrated energy system is achieved.

[0031] Please refer to Figures 1 to 4 , a method for low-carbon optimal operation of a wind-solar-hydrogen integrated energy system considering fuel cell waste heat recovery, characterized in that it includes the following steps: Step 1: Construct a waste heat recovery model of a high-temperature solid oxide fuel cell, and analyze the mechanism of promoting the consumption of wind power and photovoltaic power and reducing carbon emissions by waste heat recovery of the fuel cell. The output model of the high-temperature solid oxide fuel cell can be expressed as: In the formula: η SOFC are the hydrogen consumption power, power generation power, heat generation power and power generation efficiency of the fuel cell respectively; P SOFC,max is the maximum value of the power generation power; ΔP SOFC,max ; ΔP SOFC,min are the maximum and minimum ramp powers respectively.

[0032] The waste heat recovery device can absorb a part of the unreacted fuel in the power generation unit of the high-temperature solid oxide fuel cell for heating, as follows: In the formula: η WHB are the output heat power and recovery efficiency of the waste heat recovery device respectively; P WHB,max is the maximum output heat power of the waste heat recovery device; ΔP WHB,max , ΔP WHB,min are the maximum and minimum ramp powers respectively.

[0033] During periods when wind and solar energy are abundant, recovering the waste heat of fuel cells can effectively reduce the output of combined heat and power (CHP) units and gas boilers. Doing so can not only reduce the power supply of the CHP system but also free up more space to accommodate wind and photovoltaic energy, thereby effectively improving the utilization rate of renewable energy. In addition, by recovering the waste heat of fuel cells, carbon emissions can be reduced, making it more environmentally friendly. Therefore, considering the recovery of fuel cell waste heat during periods when wind and solar energy are abundant has a positive impact on the operation of the energy system.

[0034] Step 2: Establish a model architecture for a wind-solar-hydrogen integrated energy system considering fuel cell waste heat recovery. The output power model of combined heat and power (CHP) is as follows: In the formula: is the input natural gas power of the CHP at time t. are the output electric power and heat power of the CHP at time t, respectively; δ chp are the electric efficiency and heat-electric ratio of the CHP, respectively; is the maximum value of the input natural gas power; are the maximum and minimum ramp powers, respectively.

[0035] The output power model of gas boilers (GB) is as follows: In the formula: is the input natural gas power of the GB at time t; is the output heat power of the GB at time t; is the heat efficiency of the GB; is the maximum value of the input natural gas power; are the maximum and minimum ramp powers, respectively.

[0036] The models of electrolyzer (EL) for hydrogen production by electrolyzing water and methanation reaction (MR) are as follows: In the formula: η EL are the input electric power, output hydrogen power, and hydrogen production efficiency, respectively; is the maximum value of the input electric power; are the maximum and minimum ramp powers, respectively; is the hydrogen power input to the MR; P MR,g(t) is the output gas power of the MR; η MR is the gas production efficiency of the MR; are the maximum and minimum values of the input hydrogen power.

[0037] The energy storage model is as follows: In the formula: n represents the energy type, n ∈ {e, h, H2}; E n (t) is the stored energy of the nth energy storage device in the t time period; ε is the self-loss rate of the energy storage device; P n,in (t), P n,out (t) are the charging and discharging powers of the nth energy storage device in the t time period; η n,in , η n,out are the charging and discharging efficiencies of the nth energy storage device respectively; are the upper and lower limits of the capacity of the nth energy storage device; are both 0-1 logical variables, indicating the charging and discharging states of the nth energy storage device in the t time period; represent the maximum charging and discharging powers of the nth energy storage device respectively; T is the scheduling period.

[0038] Step 3: Establish an operation optimization model for the wind-solar-hydrogen integrated energy system considering the waste heat recovery of fuel cells. The objective function is to minimize the comprehensive cost of the system, that is, to minimize the sum of the energy purchase cost, the stepped carbon trading cost, and the penalty cost for wind and light abandonment, so as to achieve the low-carbon economic operation of the system; The objective function in the above Step 3 is: In the formula: C buy is the energy purchase cost; is the stepped carbon trading cost; C w is the penalty cost for wind and light abandonment. The energy purchase cost is: In the formula: α t , β t represent the electricity price and gas price in the t time period respectively; P g,buy (t) is the gas purchase volume in the t time period; P e,buy (t) is the electricity purchase volume in the t time period.

[0039] The penalty cost for wind and light abandonment is: In the formula: r w is the penalty coefficient for wind and light abandonment; is the upper limit of the wind power and photovoltaic power output in the t time period, that is, the predicted value of wind power and photovoltaic power; PWT (t), P PV (t) are the wind power and photovoltaic power outputs in the t time period respectively.

[0040] The stepped carbon trading cost is: In the formula: is the stepped carbon trading cost; ψ is the base price of carbon trading; μ is the price growth rate; l is the length of the unit carbon emission interval; E IES,t is the quantity of carbon emission right quota.

[0041] The quantity of carbon emission right quota is: In the formula: E IES,ι is the quantity of carbon emission right quota purchased in the carbon trading market; E IES is the actual carbon emission of the system; is the carbon emission right quota of the system.

[0042] The carbon emission right quota model is: In the formula: are the carbon emission right quotas of the superior power purchase, CHP, and GB respectively; α e , α g are the carbon emission right quotas of the coal-fired unit per unit power consumption and the gas-fired unit per unit natural gas consumption respectively; P e,buy (t) is the superior power purchase quantity at time t; T is the dispatching period.

[0043] The actual carbon emission model is: In the formula: E e,buy , E CHP , E GB are the actual carbon emissions of the external power grid power purchase, CHP, and gas boiler respectively; E P2G is the amount of carbon dioxide consumed in the production of natural gas by the P2G equipment; δ e , δ h are the actual carbon emissions of the coal-fired unit per unit electric power production and the gas-fired unit per unit thermal power production respectively; C P2G (t) represents the amount of carbon dioxide consumed by the power-to-gas equipment in the t time period.

[0044] In step 3 above, constraints such as wind-solar power output constraints, energy purchase constraints, and power balance are considered. The wind-solar power output constraints are as follows: External power grid power purchase constraint: In the formula: is the maximum value of electricity purchased from the external power grid.

[0045] External gas network gas purchase constraint: In the formula: is the maximum value of gas purchased from the external power grid. The electric power balance constraint is as follows: In the formula: are the charging and discharging powers of the energy storage device in the t time period respectively; is the electric load at time t.

[0046] The thermal power balance constraint is as follows: In the formula: are the heat storage and heat release powers of the heat storage device in the t time period respectively; is the heat load at time t.

[0047] The gas power balance constraint is as follows: The hydrogen power balance constraint is as follows: In the formula: respectively represent the hydrogen storage and hydrogen release powers of the hydrogen storage device in the t time period; is the hydrogen load.

[0048] Furthermore, the specific implementation example is as follows: mainly considering the waste heat recovery of high-temperature solid oxide fuel cells, through solving the model, it is verified that considering the waste heat recovery of fuel cells can reduce the system operation cost and improve the low-carbon performance of the system at the same time.

[0049] First, introduce the principle of the present invention. The invention principle model is the same as the above steps 1-4 and will not be elaborated here.

[0050] Second, to verify the effectiveness of the structure and model proposed in this paper, taking Figure 2 structure as the basis, an example is constructed for verification. The wind power, photovoltaic, and load forecasts are as Figure 3 shown.

[0051] To compare and verify the effectiveness of the model proposed in this paper, the following 4 scenarios are set for comparative analysis.

[0052] Scenario 1: The integrated energy dispatch without considering the waste heat recovery of fuel cells and the stepped carbon trading, only considering the ordinary carbon trading.

[0053] Scenario 2: Consider the waste heat recovery of fuel cells on the basis of Scenario 1.

[0054] Scenario 3: Consider the stepped carbon trading on the basis of Scenario 1.

[0055] Scenario 4: Consider the waste heat recovery of fuel cells on the basis of Scenario 3.

[0056] The optimization results of the above four scenarios are shown in Table 1. Table 1 Optimization operation results of four scenarios

[0057] It can be seen from Table 1 that: compared with Scenarios 1-3, the overall economic performance of the system in Scenario 4 is the best. Compared with Scenario 1, the total cost of the system decreases by 30.7%, the energy purchase cost of the system decreases by 34.2%, the carbon emission cost decreases by 20.88%, the carbon emission is reduced by 18.8%, and the curtailment cost of wind and light is also reduced to 0. Compared with Scenario 3, Scenario 4 reduces the total cost by 4.2% and has less carbon emissions. Thus, it can be seen that integrating the stepped carbon trading mechanism and the fuel cell waste heat recovery mechanism into the integrated energy can play a better role in energy conservation and emission reduction, and has good economic performance and feasibility.

[0058] Through the SOFC, EL, hydrogen storage tank and waste heat recovery device, deep coupling between electricity, heat and hydrogen can be achieved, and cascaded utilization of hydrogen energy can be realized. Considering the waste heat recovery of SOFC can reduce the carbon emission cost and energy purchase cost of the system, improve the consumption capacity of wind, light and hydrogen, reduce the carbon emissions of the system, and improve the economic performance of the system.

[0059] The specific embodiments described in the present invention are only examples to illustrate the spirit of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A low-carbon optimal operation method for a wind-solar-hydrogen integrated energy system considering waste heat recovery of fuel cells, characterized in that, It includes the following steps: Step 1: Construct a waste heat recovery model for high-temperature solid oxide fuel cells, and analyze the mechanism of promoting the consumption of wind power and photovoltaic power and reducing carbon emissions through waste heat recovery of fuel cells; Step 2: Establish a wind-solar-hydrogen integrated energy system model considering waste heat recovery of fuel cells to meet the multi-energy load demands within the system; Step 3: Establish an operation optimization model for the wind-solar-hydrogen integrated energy system considering waste heat recovery of fuel cells; The objective function is to minimize the overall system cost, that is, the objective function is to minimize the sum of the system's energy purchase cost, stepped carbon trading cost, and penalty cost for wind and photovoltaic curtailment, so as to achieve the low-carbon economic operation of the system; Step 4: Solve the model established in Step 3 to reduce the total system cost and carbon emissions.

2. A low-carbon optimal operation method for a wind-solar-hydrogen integrated energy system considering waste heat recovery of a fuel cell, characterized in that, In Step 1, the waste heat recovery model for high-temperature solid oxide fuel cells is as follows: Where: are the hydrogen consumption power, power generation power, heat generation power, and power generation efficiency of the fuel cell, respectively; P SOFC,max is the maximum value of the power generation power; ΔP SOFC,max ; ΔP SOFC,min are the maximum and minimum ramp powers, respectively; The waste heat recovery device can absorb some of the unreacted fuel in the power generation unit of the high-temperature solid oxide fuel cell for heating, as follows: Wherein: are respectively the output thermal power and the recovery efficiency of the waste heat recovery device; P WHB,max is the maximum output thermal power of the waste heat recovery device; ΔP WHB,max and ΔP WHB,min are respectively the maximum and minimum ramp-up powers.

3. A low-carbon optimal operation method for a wind-solar-hydrogen integrated energy system considering waste heat recovery of a fuel cell, characterized in that The specific integrated energy system model described in Step 2 is: In the wind-solar-hydrogen integrated energy system considering waste heat recovery of fuel cells, there are couplings of four types of energy: electricity, heat, hydrogen, and gas. The electrical energy source for the electrical load is power purchased from the external power grid, wind power generation, photovoltaic power generation, batteries, fuel cells, and combined heat and power. The heat energy source for the heat load is the fuel cell-waste heat recovery device, combined heat and power, gas boiler, and heat storage device. The source of the gas load is gas purchased from the external gas network and the methanation reaction device. At the same time, in order to promote the consumption of wind power and photovoltaic power, an electrolyzer is introduced to meet the hydrogen load within the system; Combined heat and power, abbreviated as CHP, the output power model is as follows: In the formula: is the input natural gas power of the CHP at time t. are the output electric power and heat power of the CHP at time t, respectively; are the electric efficiency and the heat - to - power ratio of the CHP, respectively; is the maximum value of the input natural gas power; are the maximum and minimum ramp powers, respectively; Gas boiler, abbreviated as GB, the output power model is as follows: Wherein: is the natural gas input power of the GB at time t; is the heat output power of the GB at time t; is the thermal efficiency of the GB; is the maximum value of the natural gas input power; are the maximum and minimum ramp powers respectively; Electrolysis of water to produce hydrogen, abbreviated as EL, and methanation reaction, abbreviated as MR, the models are as follows: where: are the input electric power, the output hydrogen power, and the hydrogen production efficiency, respectively; is the maximum value of the input electric power; are the maximum and minimum ramp powers, respectively; is the hydrogen power input to the MR; P MR,g (t) is the output gas power of the MR; η MR is the gas production efficiency of MR; are the maximum and minimum values of the input hydrogen power; The energy storage model is as follows: where: n represents the energy type, n ∈ {e, h, H2}; E n (t) is the stored energy of the nth energy storage device during the time period t; ε is the self-loss rate of the energy storage device; P n,in (t), P n,out (t) are the energy storage and discharge power of the nth energy storage device in the time period t, respectively; η n,in and η n,out are the energy storage and discharge efficiencies of the n-th energy storage device, respectively; are the upper and lower limits of the capacity of the n-th energy storage device; are both 0-1 logical variables, indicating the energy storage and discharge states of the n-th energy storage device during the t time period; represent the maximum power of energy storage and discharge of the n-th energy storage device, respectively; T is the scheduling period.

4. A low-carbon optimal operation method for a wind-solar-hydrogen integrated energy system considering waste heat recovery of a fuel cell, characterized in that, The objective function described in Step 3 is: Where: C buy is the energy purchase cost; is the stepped carbon trading cost; C w is the penalty cost for wind and PV curtailment; The energy purchase cost is: Where: α t , β t respectively represent the electricity price and gas price in the t time period; P g,buy (t) is the gas purchase volume in the t time period; P e,buy (t) is the electricity purchase volume in the t time period; The penalty cost for wind and photovoltaic curtailment is: Where: r w is the penalty coefficient for curtailed wind and solar power; is the upper limit of wind power and photovoltaic power output in the t time period, that is, the predicted value of wind power and photovoltaic power; P WT (t), P PV (t) are the wind power and photovoltaic power output in the t time period respectively; The stepped carbon trading cost is: In the formula: is the stepped carbon trading cost; ψ is the base price of carbon trading; μ is the price growth rate; l is the length of the unit carbon emission interval; E IES,t is the quantity of carbon emission allowance; The quantity of carbon emission allowances is: Where: E IES,ι is the quantity of carbon emission allowance purchased in the carbon trading market; E IES is the actual carbon emissions of the system; is the carbon emission allowance of the system; The carbon emission allowance model is: Wherein: are respectively the carbon emission quota for the upper-level power purchase, CHP, and GB; α e , α g are respectively the carbon emission quota for the unit power consumption of the coal-fired unit and the unit natural gas consumption of the natural gas-fired unit; P e,buy (t) is the upper-level power purchase amount at time t; T is the dispatching period; The actual carbon emission model is: Where: E e,buy , E CHP , E GB are the actual carbon emissions of purchasing electricity from the external power grid, CHP, and gas boilers, respectively; E P2G is the amount of carbon dioxide consumed in the production of natural gas by the P2G equipment; δ e , δ h are the actual carbon emissions per unit of electric power produced by the coal-fired unit and the actual carbon emissions per unit of thermal power produced by the natural gas-fired unit, respectively; C P2G (t) represents the amount of carbon dioxide consumed by the power-to-gas equipment in the t time period.

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