Novel comprehensive energy system considering carbon trading market and two-stage electricity-to-gas conversion

Abstract

The invention relates to a novel comprehensive energy system considering a carbon trading market and two-stage electricity-to-gas conversion, and belongs to the field of novel energy systems. The system introduces a stepped carbon transaction mechanism to guide the carbon emission of the novel energy system by considering that the novel energy system participates in a carbon transaction market; meanwhile, the two-stage operation process of converting electricity into gas is refined, and an electrolytic bath, a methane reactor and a hydrogen fuel cell are introduced to replace a traditional hydrogen production mode; and finally, combined heat and power generation with the adjustable heat and power ratio is provided, and a thermoelectric conversion device and a combined heat and power generation device are added into an energy system to further improve the low-carbon property and economical efficiency of the system. Based on this, a low-carbon economic operation target with minimum energy purchase cost, carbon emission cost and wind curtailment cost is constructed, an original problem is converted into a mixed integer linear problem, and the effectiveness of the proposed strategy is compared and verified by setting a plurality of operation scenes.

Description

Technical Field

[0001] The present invention belongs to the field of new energy systems, and particularly relates to a new integrated energy system considering the carbon trading market and two-stage power-to-gas. Background Art

[0002] As the main body of energy consumption in the social power industry, its carbon emissions account for a large proportion of the total carbon emissions. Achieving low-carbon power is expected to accelerate the goal of carbon emission reduction. The integrated energy system IES (Integrated Energy System) internally couples multiple energy sources for combined supply, can meet the multi-energy load demands of terminals, and further optimizes the low-carbon economy of the multi-energy system.

[0003] However, most current carbon emission models are too simple and do not fully consider the role of the carbon trading market; when using power-to-gas to promote the consumption of wind power, few consider the benefits of the two-stage power-to-gas operation process; when optimizing the operation of a combined heat and power plant, the potential advantages of an adjustable heat-to-power ratio are rarely considered. At the same time, few comprehensively consider the impact of the coordinated operation of a stepped carbon trading mechanism, the refinement of the two-stage power-to-gas operation, and a combined heat and power plant with an adjustable heat-to-power ratio on the dispatching of a new energy system. Summary of the Invention

[0004] The purpose of the present invention is to provide a new integrated energy system considering the carbon trading market and two-stage power-to-gas, introducing the carbon trading market, the two-stage power-to-gas process, and a combined heat and power plant with an adjustable heat-to-power ratio, and ultimately achieving the purpose of reducing the operating cost and carbon emissions of the system by reducing wind curtailment, the gradient loss of energy, and the impact caused by the uncertainty of new energy output.

[0005] To achieve the above purpose, the technical solution of the present invention is: a new integrated energy system considering the carbon trading market and two-stage power-to-gas, including a superior energy supply unit, a coupling equipment unit, an energy storage equipment unit, a terminal energy consumption unit, and further including a carbon trading market unit, introducing the carbon trading market, and using a stepped carbon trading mechanism to guide the carbon emissions of the new integrated energy system. At the same time, the two-stage operation process of power-to-gas is refined, and a thermoelectric conversion device and a combined heat and power plant are added to the new integrated energy system.

[0006] In an embodiment of the present invention, the superior energy supply unit is composed of a gas network, a power grid, and a wind power system; the coupling equipment unit is composed of a boiler GB, a methane reactor MR, and an electrolyzer EL, and a thermoelectric conversion device HFC and a combined heat and power plant CHP are added; the energy storage equipment unit is composed of devices capable of storing electric energy, thermal energy, and natural gas respectively, and a hydrogen storage tank is added; the terminal energy consumption unit is composed of several users.

[0007] In an embodiment of the present invention, the system optimization scheduling method is specifically as follows:

[0008] Step S1: Construct the initial framework of the integrated energy system model, including the superior energy supply unit, the coupling equipment unit, the energy storage equipment unit, and the terminal energy consumption unit. Among them, the superior energy supply unit consists of a gas network, a power grid, and a wind power system; the coupling equipment unit consists of a boiler GB, a methane reactor MR, and an electrolyzer EL; the energy storage equipment unit consists of devices that can store electric energy, thermal energy, and natural gas respectively; the terminal energy consumption unit consists of several users; introduce a carbon trading market unit under the integrated energy system framework to construct a new integrated energy system;

[0009] Step S2: Introduce two-stage power-to-gas, add a thermoelectric conversion device HFC to the coupling equipment unit, and add a hydrogen storage tank to the energy storage equipment unit to improve the conversion efficiency of hydrogen energy and reduce the gradient loss of energy;

[0010] Step S3: Add a combined heat and power generation device CHP to the coupling equipment unit so that the heat-to-power ratio can be continuously adjusted over time;

[0011] Step S4: Construct the objective function and constraint conditions of the new integrated energy system, and establish a mixed-integer nonlinear model;

[0012] Step S5: Linearize the mixed-integer nonlinear model constructed in Step S4, and convert the mixed-integer nonlinear model into a mixed-integer linear model through a commercial solver;

[0013] Step S6: Obtain the optimal load model of the new integrated energy system by solving.

[0014] In an embodiment of the present invention, the specific implementation method of introducing a carbon trading market and adopting a stepped carbon trading mechanism to guide the carbon emissions of the new integrated energy system is as follows:

[0015] Introduce a carbon trading market, and at the same time adopt a stepped pricing mechanism to adjust the carbon trading cost under different carbon emissions, which is divided into multiple intervals. The following formula is the trading volume of the carbon trading cost in different intervals:

[0016]

[0017] In the formula: is the stepped carbon trading cost; λ is the basic carbon trading price; l_thermal is the interval length of carbon emissions; α_electric is the price growth rate, and E IES,t is the carbon emission trading volume of the IES.

[0018] In an embodiment of the present invention, the mixed-integer nonlinear model is an IES low-carbon economic scheduling model considering power-to-hydrogen and adjustable heat-to-power ratio, which is a mixed-integer nonlinear model.

[0019] In an embodiment of the present invention, the mixed-integer non-linear model is converted into a mixed-integer linear model by using Yalmip to call the CPLEX commercial solver.

[0020] In an embodiment of the present invention, the mixed-integer non-linear model is converted into a mixed-integer linear model by using Yalmip to call the CPLEX commercial solver, and the solution process is as follows:

[0021] According to the required accuracy, take Q + 1 segmentation points [r 1 , r 2 , …, r Q+1 to divide the original function into Q intervals, and add Q + 1 continuous auxiliary variables [w 1 , w 2 , …, w Q+1 and Q binary-type auxiliary variables [z 1 , z 2 , …, z Q to satisfy the following formula:

[0022]

[0023] Replace the non-linear function with a linear expression as follows:

[0024]

[0025] In the formula: P e,buy is the electricity purchase quantity from the superior, and E e,buy,a is the actual carbon emission of the electricity purchased from the superior.

[0026] In an embodiment of the present invention, the working mode of the combined heat and power generation is as follows:

[0027]

[0028] In the formula: P g,CHP (t) is the natural gas power input to the combined heat and power generation device at time t; are the efficiencies of converting the combined heat and power generation device into electric energy and heat energy respectively; P CHP,e (t), P CHP,h (t) are the electric energy and heat energy output by the combined heat and power generation device at time t respectively; are the upper and lower limits of the natural gas power input to the combined heat and power generation device respectively; are the upper and lower limits of the ramp of the combined heat and power generation device respectively.

[0029] In an embodiment of the present invention, the objective function of the new integrated energy system is to construct an objective function with the total cost of the new integrated energy system, including the energy purchase cost, the stepped carbon trading cost, and the wind abandonment cost.

[0030] In an embodiment of the present invention, the constraint conditions of the new integrated energy system include wind power output constraint, operation constraints of each system, electro-thermal power balance constraint, natural gas balance constraint, and hydrogen balance constraint.

[0031] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a new integrated energy system considering the carbon trading market and two-stage power-to-gas. By introducing the carbon trading market, the two-stage power-to-gas process, and a combined heat and power generation device with adjustable heat-to-power ratio, the impact caused by reducing wind curtailment, gradient loss of energy, and reducing the uncertainty of new energy output is reduced, and finally the purpose of reducing the operating cost and carbon emissions of the system is achieved. Description of the Drawings

[0032] Figure 1 is the method flow chart in an embodiment of the present invention;

[0033] Figure 2 is the overall system structure schematic diagram in an embodiment of the present invention;

[0034] Figure 3 is the two-stage power-to-gas operation schematic diagram in an embodiment of the present invention;

[0035] Figure 4 is the 24-hour regulation ratio schematic diagram of the heat-to-power ratio adjustable device in an embodiment of the present invention;

[0036] Figure 5 is the optimal scheduling schematic diagram of the system in an embodiment of the present invention. Detailed Embodiment

[0037] Next, in conjunction with the drawings, the technical solutions of the present invention will be specifically described.

[0038] The present invention provides a new integrated energy system considering the carbon trading market and two-stage power-to-gas, including a superior energy supply unit, a coupling device unit, an energy storage device unit, a terminal energy consumption unit, and also including a carbon trading market unit. The carbon trading market is introduced, and a stepped carbon trading mechanism is adopted to guide the carbon emissions of the new integrated energy system. At the same time, the two-stage operation process of power-to-gas is refined, and a thermoelectric conversion device and a combined heat and power generation device are added to the new integrated energy system. The superior energy supply unit is composed of a gas network, a power grid, and a wind power system; the coupling device unit is composed of a boiler GB, a methane reactor MR, and an electrolyzer EL, and a thermoelectric conversion device HFC and a combined heat and power generation device CHP are added; the energy storage device unit is composed of devices that can store electric energy, heat energy, and natural gas respectively, and a hydrogen storage tank is added; the terminal energy consumption unit is composed of several users.

[0039] The following is the specific implementation process of the present invention.

[0040] Please refer toFigure 1 , this example provides a new integrated energy system considering the carbon trading market and two-stage power-to-gas, and its optimal scheduling method includes the following steps:

[0041] Step S1, as Figure 2 shown, construct the initial framework of the common integrated energy system model, including four main components: the superior energy supply unit, the coupling equipment unit, the energy storage equipment unit, and the terminal energy consumption unit;

[0042] Step S2, after building the preliminary framework of the system, add equipment under different unit frameworks to ensure the normal operation of the system;

[0043] Among them, the superior energy supply unit consists of a gas network, a power grid, and a wind power system; the coupling equipment unit consists of a boiler GB, a methane reactor MR, and an electrolyzer EL; the energy storage equipment unit consists of devices that can store electric energy, thermal energy, and natural gas respectively; the terminal energy consumption unit consists of several users;

[0044] Step S3, introduce the carbon trading market unit under the above integrated energy system framework, and consider the role of the carbon trading market;

[0045] Step S4, introduce two-stage power-to-gas, add a heat-electric conversion device HFC in the coupling equipment unit, and add a hydrogen storage tank in the energy storage equipment unit to improve the conversion efficiency of hydrogen energy and reduce the gradient loss of energy;

[0046] Step S5, add a combined heat and power device CHP in the coupling equipment unit, so that the heat-electric ratio can be continuously adjusted with time, further improve the energy utilization efficiency, and at the same time complete the establishment of the system model;

[0047] Step S6, construct the objective function and constraint conditions, and establish the mathematical model for system verification;

[0048] Step S7, perform linearization processing on the model, and convert the original mixed-integer non-linear model into a mixed-integer linear model through a commercial solver;

[0049] Step S8, obtain the optimal load model of the integrated energy system by solving.

[0050] In this example, by obtaining the carbon emission right quota and the actual carbon emissions of the IES, the carbon emission right trading volume actually participating in the carbon trading market can be obtained.

[0051] E IES,t = E IES,a - E IES

[0052] In the formula: E IES,t is the carbon emission right trading volume of the IES at time t, EIES,a is the actual carbon emission of the IES, E IES is the carbon emission trading volume of the IES.

[0053] Compared with the traditional carbon trading pricing mechanism, in order to further limit carbon emissions, the present invention adopts a stepped pricing mechanism. The stepped pricing mechanism divides multiple purchase intervals. As the quota of carbon emission rights to be purchased is more, the purchase price of the corresponding interval is higher. The stepped carbon trading cost is:

[0054]

[0055] In the formula: is the stepped carbon trading cost; λ is the basic carbon trading price; l_thermal is the interval length of carbon emissions; α_electricity is the price growth rate.

[0056] Figure 3 is the schematic diagram of the two-stage power-to-gas operation in an embodiment of the present invention. EL first converts electric energy into hydrogen energy. Part of the hydrogen energy is input into MR and combined with CO to synthesize natural gas, which is supplied to the gas load. The part of GB and CHP is directly transported to HFC to be converted into electric and thermal energy. Another part is stored via the hydrogen storage tank. The direct conversion of hydrogen energy into electric and thermal energy via HFC reduces an energy conversion link compared with first converting it into natural gas and then burning it via GB or CHP for supply, which can reduce the cascading loss of energy. In addition, the energy efficiency of hydrogen energy is higher than that of natural gas and it does not produce CO. It can be seen that directly supplying hydrogen energy to HFC has multiple benefits.

[0057] In this example, CHP generates electricity by burning natural gas and supplies the waste heat generated during the power generation process to the heat load. The CHP with adjustable thermoelectric ratio can adjust the electric and heat output according to the real-time electric and heat energy demands, further optimizing the operation benefits. Figure 4 Shown is the schematic diagram of the 24-hour adjustment ratio of the device with adjustable thermoelectric ratio in an embodiment of the present invention.

[0058] Figure 5 is the schematic diagram of the optimal scheduling of the system in an embodiment of the present invention. By comparing the final result with most existing energy systems, it can be found that the system described in this patent is significantly superior to most existing energy systems in reducing the operating cost and carbon emissions of the system.

[0059] The above are the preferred embodiments of the present invention. All changes made according to the technical solution of the present invention and whose functional effects do not exceed the scope of the technical solution of the present invention belong to the protection scope of the present invention.

Claims

1. A new integrated energy system considering carbon trading market and two-stage power-to-gas, characterized in that: It includes superior energy supply units, coupling equipment units, energy storage equipment units, terminal energy consumption units, and carbon trading market units. It introduces a carbon trading market and adopts a step-by-step carbon trading mechanism to guide the carbon emissions of the new integrated energy system. At the same time, it refines the two-stage operation process of electricity to gas, and adds heat and power conversion devices and cogeneration devices to the new integrated energy system.

2. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 1, characterized in that: The upper-level energy supply unit is composed of the gas grid, the power grid and the wind power system; the coupling equipment unit is composed of the boiler GB, the methane reactor MR and the electrolyzer EL, and is supplemented with the thermoelectric conversion device HFC and the cogeneration device CHP; the energy storage equipment unit is composed of devices that can store electrical energy, thermal energy and natural gas respectively, and is supplemented with hydrogen storage tanks; the terminal energy consumption unit is composed of several users.

3. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 2, characterized in that: The optimization scheduling method of the system is as follows: Step S1, construct the initial framework of the integrated energy system model, including the upper energy supply unit, the coupling device unit, the energy storage device unit, and the terminal energy unit, wherein the upper energy supply unit is composed of the gas grid, the power grid and the wind power system; the coupling device unit is composed of the boiler GB, the methane reactor MR and the electrolyzer EL; the energy storage device unit is composed of devices that can store electrical energy, thermal energy and natural gas respectively; the terminal energy unit is composed of several users; the carbon trading market unit is introduced under the framework of the integrated energy system to construct a new integrated energy system; Step S2, introducing a two-stage power-to-gas conversion, adding a thermoelectric converter HFC in the coupling device unit, and adding a hydrogen storage tank in the energy storage device unit, so as to improve the conversion efficiency of hydrogen energy and reduce the gradient loss of energy; Step S3, adding a combined heat and power device CHP to the coupling device unit, so that the hot spot ratio can be continuously adjusted with time; Step S4, constructing the objective function and constraint conditions of the new integrated energy system and establishing a mixed integer nonlinear model; Step S5, linearizing the mixed integer nonlinear model constructed in step S4, and converting the mixed integer nonlinear model into a mixed integer linear model through a commercial solver; Step S6: Obtain the optimal load model of the new integrated energy system by solving.

4. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 1 or 3, characterized in that: The specific implementation methods of introducing a carbon trading market and adopting a tiered carbon trading mechanism to guide the carbon emissions of the new integrated energy system are: The carbon trading market is introduced, and a tiered pricing mechanism is adopted to adjust the carbon trading costs under different carbon emissions, which are divided into multiple intervals. The following formula is the trading volume of carbon trading costs under different intervals: Where: is the step-by-step carbon trading cost; λ is the basic price of carbon trading; l is the interval length of carbon emissions; α is the price growth rate, E IES,t is the carbon emission rights trading amount of IES.

5. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 3, characterized in that: The IES low-carbon economic dispatch model that considers electric hydrogen production and adjustable heat-to-electricity ratio is a mixed integer nonlinear model.

6. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 5, characterized in that: The mixed integer nonlinear model is converted into a mixed integer linear model by calling the CPLEX commercial solver using Yalmip.

7. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 6, characterized in that: The mixed integer nonlinear model is converted into a mixed integer linear model by calling the CPLEX commercial solver using Yalmip. The solution process is as follows: According to the required accuracy, select Q+1 segmentation points [r1, r2, …, r Q+1 ] Divide the original function into Q intervals and add Q+1 continuous auxiliary variables [w1,w2,…,w Q+1 ] and Q binary auxiliary variables [z1,z2,…,z Q ], satisfying the following formula: Replace the nonlinear function with a linear expression as follows: Where: P e,buy E is the amount of electricity purchased from the superior. e,buy,a The actual carbon emissions from purchasing electricity from the upper level.

8. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 1 or 3, characterized in that: The working mode of cogeneration is as follows: Where: P g,CHP (t) is the natural gas power input to the cogeneration unit at time t; are the conversion efficiencies of the cogeneration device into electrical energy and thermal energy respectively; P CHP,e (t), P CHP,h (t) are the electrical energy and thermal energy output by the cogeneration device at time t, respectively; are the upper and lower limits of the natural gas power input into the cogeneration unit, respectively; They are the upper and lower limits of the ramping of the cogeneration unit respectively.

9. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 3, characterized in that: The objective function of the new integrated energy system is constructed based on the total cost of the new integrated energy system, including energy purchase cost, tiered carbon trading cost and wind curtailment cost.

10. A new integrated energy system considering carbon trading market and two-stage power-to-gas according to claim 3, characterized in that: The constraints of the new integrated energy system include wind power output constraints, operation constraints of each system, electric and thermal power balance constraints, natural gas balance constraints, and hydrogen balance constraints.

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