Energy efficiency-carbon-flexibility collaborative analysis method for integrated energy system containing Carnot cell

Abstract

The invention provides an energy efficiency-carbon-flexibility collaborative analysis method for a comprehensive energy system containing a Carnot battery, and the method can evaluate the gain / attenuation condition of an energy efficiency-carbon-flexibility index in a multi-working-condition scene, and can recognize an operation mode which can bring significant gain or attenuation of the energy efficiency-carbon-flexibility index. According to the method, energy efficiency, carbon emission and comprehensive flexibility indexes of a comprehensive energy system are constructed, an energy efficiency-carbon-flexibility collaborative index system is formed, a Lagrangian function is constructed, a KKT condition is established, the optimization problem of an equation related to processing of the Lagrangian function is popularized to an inequality, an inequality equation set containing a Lagrangian multiplier is obtained, and the energy efficiency, carbon emission and comprehensive flexibility indexes of the comprehensive energy system are obtained. And analyzing the influence of the unit change of any index on other indexes by using an inequality equation set containing a Lagrange multiplier, and guiding the multi-energy complementary operation optimization of the integrated energy system.

Description

Technical Field

[0001] The present invention relates to an integrated energy system based on a Carnot battery, and mainly relates to an "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing a Carnot battery. Background Art

[0002] In the context of large demand for renewable energy consumption, high requirements for dynamic balance between supply and demand, and difficulty in flexible operation of the system, energy storage equipment has gradually become an indispensable part of the integrated energy system. From the perspective of the integrated energy system, the Carnot battery can not only provide abundant energy storage resources for the integrated energy system, but also give the system a high degree of flexibility through energy storage and release and multi-energy complementarity. It is the core equipment for the integrated energy system to achieve multi-directional dynamic matching of energy quality and flexible operation between various energy flows. One of the keys to the further development of the Carnot battery is to integrate the integrated energy system and its flexible control technology to achieve efficient storage and utilization of multiple energies.

[0003] The multi-energy complementarity of the integrated energy system based on Carnot batteries is mainly driven by the changes in the storage and release conditions of the Carnot batteries. The multi-energy complementarity operation of this new integrated energy system requires comprehensive consideration of energy quality factors. How to further understand the "energy efficiency-carbon-flexibility" collaborative operation mechanism at the theoretical level is the key to the flexible optimization and scheduling of energy and carbon in the integrated energy system based on Carnot batteries. Existing research on the characterization of the source and composition of flexibility mainly focuses on load-side energy consumption. There is insufficient research on the characterization methods of flexible operation dimensions, and the understanding of the "energy efficiency-carbon-flexibility" collaborative mechanism is not clear enough. The dynamic operation and energy storage and release process of the integrated energy system based on Carnot batteries involves not only energy efficiency (including efficiency) and carbon, but also involves the flexibility of the three levels of "equipment-energy flow-system". New methods are needed to build new flexibility quantitative theoretical models to analyze and deconstruct the optimization and scheduling of integrated energy systems in energy efficiency (including efficiency), carbon, and flexibility. Summary of the invention

[0004] The purpose of the present invention is to provide a "energy efficiency-carbon-flexibility" synergistic analysis method for an integrated energy system containing a Carnot battery. The method can reveal the synergistic mechanism of "energy efficiency-carbon-flexibility", solve the unclear gain / attenuation problem of the "energy efficiency-carbon-flexibility" indicators in the integrated energy system, and contribute to the multi-energy complementarity and energy-carbon synergistic operation of the integrated energy.

[0005] The present invention is implemented by the following technical solutions:

[0006] A "energy efficiency-carbon-flexibility" collaborative analysis method for an integrated energy system containing a Carnot battery comprises the following steps:

[0007] Step S1, calculate the energy efficiency of the integrated energy system (including efficiency).

[0008] Determine the carbon accounting boundary of the system, that is, all energy inputs, outputs and conversion equipment involved in the system. Typical boundaries include different forms of energy inputs and outputs such as electricity, steam, compressed air, and heat.

[0009] Collect multi-energy input data and record all energy inputs received by the system within a unit time period, including input electric energy E in,electric , Steam E in,steam , compressed air E in,air wait.

[0010] Collect the output data of multiple energy sources and record all energy outputs generated by the system within a unit time period, including the output electric energy E out,electric , Steam E out,steam , compressed air E out,air wait.

[0011] Calculate the energy Values ​​are used to represent the quality of different energy types, thereby calculating the energy efficiency of the comprehensive energy system. The specific calculation method is as follows:

[0012] Step S11, electrical energy is used as secondary energy. The value is equal to its energy value, that is, Ex electric =E electric .

[0013] Step S12, steam ValueEx steam The temperature needs to be considered, which can be calculated using the thermodynamic formula:

[0014] Ex steam =hT 0 s

[0015] Where h is the specific enthalpy, T 0 is the ambient temperature and s is the specific entropy.

[0016] Step S13, compressed air ValueEx air The pressure and temperature also need to be considered, and the calculation formula is as follows:

[0017]

[0018] Where R is the gas constant, P is the air pressure, P 0 is the ambient pressure, and k is the specific heat ratio.

[0019] Step S14: All input and output energy The total system input is obtained by summing the values. Value and system output total value:

[0020] Ex in,total =∑Ex in =E in,electric +E in,steam +E in,air

[0021] Ex out,total =∑Ex out =E out,electric +E out,steam +E out,air

[0022] Step S15, the system energy efficiency is the total output Value and input total The ratio of the values ​​reflects the efficiency of energy conversion and utilization of the system under specific carbon accounting boundary conditions, and takes into account the quality of input and output energy. The calculation method is as follows:

[0023]

[0024] Step S2, determine the types of activities that should be included in the carbon accounting (determined according to actual conditions), select carbon emission factors based on industry standards within the carbon accounting boundary, and calculate the carbon emissions of the integrated energy system.

[0025] For each fossil fuel, direct carbon emissions are calculated based on its consumption and carbon emission factor. The calculation formula is:

[0026]

[0027] Where E fuel is the total carbon emissions from fuel combustion, is the consumption of the i-th energy source, is the carbon emission factor of the i-th energy source, in kgCO 2 e / kg.

[0028] The carbon emissions calculation method is as follows:

[0029] E GHG =E en +E tran +E mat +E dir +E dis -R

[0030] E en =E fuel +E ele +E heat

[0031] Where E GHG is the total emission, E en Carbon emissions from energy consumption, E tran is the carbon emissions from transportation, E mat is the carbon emission of consumed materials, E dir For direct CO 2 Form of emission; E dis is the emission from the waste treatment process, R is CO 2 Recovery amount, E ele E is the emissions from purchased net electricity; heat Emissions from net purchased heat.

[0032] Step S3, calculating the comprehensive flexibility index of "equipment-energy flow-system".

[0033] The flexibility of the comprehensive energy system containing Carnot batteries includes five indicators: response speed, load tracking capability, energy scheduling flexibility, energy storage conversion efficiency and energy storage capacity utilization.

[0034] Step S31, define the system response time constant (τ), which represents the time required for the system to adjust from the current state to the target state. The response speed is expressed as the inverse of the time constant:

[0035]

[0036] Step S32, load tracking error (∈ tracking ) is used to measure the load tracking capability of the system within a certain period of time, which can characterize the multi-energy complementary flexibility of the system and is calculated by the difference between the system output power and the load demand power:

[0037]

[0038] Where P output is the system output power, P demand The power demanded by the load.

[0039] The load following capability of the integrated energy system is defined as the inverse of the load following error:

[0040]

[0041] Step S33, using energy conversion efficiency (η conversion ) and conversion time (t conversion ) is used to measure the flexibility of energy scheduling. Conversion time refers to the time required for the system to complete the conversion of energy form from receiving the conversion instruction. The energy conversion efficiency is calculated as follows:

[0042]

[0043] Among them, E out is the output energy, E in For input energy.

[0044] Energy dispatch flexibility can be expressed as:

[0045]

[0046] Step S34, the energy storage conversion efficiency η of the Carnot battery storage That is the energy storage conversion efficiency index:

[0047] F storage =η storage

[0048]

[0049] Among them, Q released is the heat energy released from the heat storage medium by the Carnot battery, Q stored is the thermal energy initially stored in the Carnot battery.

[0050] Step S35, actual utilization rate U of the Carnot battery energy storage capacity capacity That is the energy storage capacity utilization index F capacity :

[0051] F capacity =U capacity

[0052]

[0053] Step S36: A comprehensive flexibility score is obtained by weighted averaging the five indicators of response speed, load tracking capability, energy dispatch flexibility, energy storage conversion efficiency, and energy storage capacity utilization. The weights can be adjusted according to specific application scenarios and requirements:

[0054] F total =ω 1 ·F response +ω 2 ·F tracking +ω 3 ·F scheduling +ω 4 ·F storage +ω 5 ·F capacity

[0055] Among them, ω 1 ,ω 2 ,ω 3 ,ω 4 ,ω 5They are response speed, load tracking capability, energy scheduling flexibility, energy storage conversion efficiency and energy storage capacity utilization weight coefficient, satisfying ω 1 +ω 2 +ω 3 +ω 4 +ω 5 =1.

[0056] Step S4, establish an optimization problem for the three indicators of comprehensive energy system energy efficiency, carbon emissions and comprehensive flexibility index established in the previous step, specifically, Efficiency), carbon emissions, and flexibility are used as the objective function, and the remaining indicators are included in the constraints.

[0057] Step S41: The total carbon emissions E GHG As an example of the objective function, the system energy efficiency η ex and comprehensive flexibility index F total As constraints, the optimization problem is established:

[0058] min E GHG

[0059] Subject to: ex ≥η ex,min , F total ≥F total,min

[0060] Among them, η ex,min is the lower limit of system energy efficiency, F total,min is the lower limit of the comprehensive flexibility index;

[0061] Step S42: Set the system energy efficiency η ex As the objective function, the total carbon emissions E GHG and comprehensive flexibility index F total As constraints, the optimization problem is established:

[0062] maxη ex

[0063] Subject to:E GHG ≤E GHG,max , F total ≥F total,min

[0064] Among them, E GHG,max is the upper limit of total carbon emissions;

[0065] Step S43: The comprehensive flexibility index F total As the objective function, the total carbon emissions E GHG and system energy efficiency η ex As constraints, the optimization problem is established:

[0066] maxF total

[0067] Subject to:E GHG ≤E GHG,max , η ex ≥η ex,min

[0068] Step S5, constructing a Lagrangian function, specifically by adding the constraint conditions to the objective function through Lagrangian multipliers.

[0069] Step S51: The total carbon emissions E GHG As the objective function, construct the Lagrangian function:

[0070] L(E GHG ,η ex ,F total ,λ 1 ,λ 2 )=E GHG +λ 1 (η ex,min -η ex )+λ 2 (F total,min -F total ) where λ 1 and λ 2 is the Lagrange multiplier;

[0071] Step S52: Set the system energy efficiency η ex As the objective function, construct the Lagrangian function:

[0072] L(E GHG ,η ex ,F total ,λ 1 ,λ 2 ) = η ex -λ 1 (E GHG -E GHG,max )-λ 2 (F total,min -F total )

[0073] Step S53: The comprehensive flexibility F total As the objective function, construct the Lagrangian function:

[0074] L(E GHG ,v ex ,F total ,λ 1 ,λ 2 )=F total -λ 1 (EGHG -E GHG,max )-λ 2 (η ex,min -η ex )

[0075] Step S6, establishing Karush-Kuhn-Tucker (KKT) conditions, generalizing the optimization problem involving equations handled by the Lagrangian function to inequalities, and obtaining a system of inequality equations containing Lagrangian multipliers.

[0076] The total carbon emissions E GHG As the objective function, the specific process is:

[0077] Step S61, the gradient of the Lagrangian function is zero (i.e., a first-order necessary condition):

[0078]

[0079] Step S62, original constraint condition is satisfied:

[0080] η ex ≥η ex ,min (4)

[0081] F total ≥F total ,min (5)

[0082] Step S63, non-negativity condition of Lagrange multiplier:

[0083] λ 1 ≥0 (6)

[0084] λ 2 ≥0 (7)

[0085] Step S64, complementary relaxation condition:

[0086] λ 1 (η ex,min -η ex )=0 (8)

[0087] λ 2 (F total,min -F total )=0 (9)

[0088] Based on system energy efficiency η ex As the objective function, the specific process is:

[0089] Step S65, the gradient of the Lagrangian function is zero (i.e., a first-order necessary condition):

[0090]

[0091] Step S66, original constraint condition is satisfied:

[0092] E GHG ≤E GHG ,max (13)

[0093] F total ≥F total ,min (14)

[0094] Step S67, non-negativity condition of Lagrange multiplier:

[0095] λ 1 ≥0 (15)

[0096] λ 2 ≥0 (16)

[0097] Step S68, complementary relaxation condition:

[0098] λ 1 (E GHG -E GHG,max )=0 (17)

[0099] λ 2 (F total,min -F total )=0 (18)

[0100] The comprehensive flexibility index F total As the objective function, the specific process is:

[0101] Step S69, the gradient of the Lagrangian function is zero (i.e., a first-order necessary condition):

[0102]

[0103] Step S610, original constraint condition is satisfied:

[0104] E GHG ≤E GHG,max (twenty two)

[0105] η ex ≥η ex,min (twenty three)

[0106] Step S611, non-negativity condition of Lagrange multipliers:

[0107] λ 1 ≥0 (24)

[0108] λ 2 ≥0 (25)

[0109] Step S612, complementary relaxation condition:

[0110] λ 1 (E GHG -E GGG,max )=0 (26)

[0111] λ 2 (η ex,min -η ex )=0 (27)

[0112] Analyze the inequality equations containing Lagrange multipliers obtained in step (6):

[0113] The total carbon emissions E GHG When used as the objective function, the specific analysis process is:

[0114] From formula (1), we can get: It shows that the objective function is GHG The partial derivative of is 1.

[0115] From (2), we can get 1 =0, indicating that when the system energy efficiency reaches its minimum value, λ 1 =0.

[0116] From formula (3), we can get 2 =0, indicating that when the comprehensive flexibility reaches its minimum value, λ 2 =0.

[0117] From equations (4) and (5), it can be concluded that the system energy efficiency and comprehensive flexibility must meet their lower limit constraints.

[0118] From equations (8) to (9) (complementary relaxation conditions), we can obtain that when η ex When λ is equal to its lower limit, 1 can be non-zero; when η ex When λ is greater than its lower limit, 1 = 0. Similarly, when F total When λ is equal to its lower limit, 2 can be non-zero; when F total When λ is greater than its lower limit, 2 =0.

[0119] Based on system energy efficiency η ex When used as the objective function, the specific analysis process is:

[0120] From formula (10), we can get: It shows that the objective function is ex The partial derivative of is 1.

[0121] From (11), we can get 1 = 0, indicating that when the total carbon emissions reach their maximum value, λ 1 =0.

[0122] From (12), we can get 2 =0, indicating that when the comprehensive flexibility reaches its minimum value, λ 2 =0.

[0123] From equations (13) and (14), we can conclude that total carbon emissions must meet its upper limit constraint, and comprehensive flexibility must meet its lower limit constraint.

[0124] From equations (17) to (18) (complementary relaxation conditions), we can obtain that when E GHG When λ is equal to its upper limit, 1 can be non-zero; otherwise, λ 1 = 0. When F total When λ is equal to its lower limit, 2 can be nonzero; otherwise, λ 2 =0.

[0125] With comprehensive flexibility total When used as the objective function, the specific analysis process is:

[0126] From formula (19), we can get: It shows that the objective function is F total The partial derivative of is 1.

[0127] From (20), we can get 1 = 0, indicating that when the total carbon emissions reach their maximum value, λ 1 =0.

[0128] From equation (21), we can get 2 =0, indicating that when the system energy efficiency reaches its minimum value, λ 2 =0.

[0129] From equations (22) and (14), we can conclude that the total carbon emissions must meet its upper limit constraint, and the system energy efficiency must meet its lower limit constraint.

[0130] From equations (26) to (27) (complementary relaxation conditions), we can obtain that when E GHG When λ is equal to its upper limit, 1 can be nonzero; otherwise, λ 1 = 0. When η ex When λ is equal to its lower limit, 2 can be nonzero; otherwise, λ 2 =0.

[0131] S7, based on the inequality equations containing Lagrange multipliers, analyze the impact of a unit change in any indicator on other indicators;

[0132] The total carbon emissions E GHG As the objective function:

[0133] S71, Lagrange multiplier λ 1 represents the marginal impact of changes in system energy efficiency on total carbon emissions. Specifically, λ 1 The value of represents the change in total carbon emissions caused by a one-unit improvement in system energy efficiency. 1 >0, improving unit system energy efficiency will reduce total carbon emissions by λ 1 ; if λ 1 <0, improving unit system energy efficiency will increase total carbon emissions by λ 1 .

[0134] S72, Lagrange multiplier λ 2 represents the marginal impact of changes in the comprehensive flexibility index on total carbon emissions. Specifically, λ 2 The value of represents the change in total carbon emissions caused by a one-unit increase in the comprehensive flexibility index. 2 >0, increasing the unit comprehensive flexibility index will reduce the total carbon emissions by λ 2 ; if λ 2 <0, increasing the unit comprehensive flexibility index will increase the total carbon emissions by λ 2 .

[0135] Based on system energy efficiency η ex As the objective function, the specific process is:

[0136] S73, Lagrange multiplier λ 1 represents the marginal impact of changes in total carbon emissions on system energy efficiency. Specifically, λ 1 The value of represents the change in total carbon emissions caused by a one-unit improvement in system energy efficiency. 1 >0, increasing total carbon emissions will reduce system energy efficiency λ 1 ; if λ 1 <0, increasing total carbon emissions will increase system energy efficiency λ 1 .

[0137] S74, Lagrange multiplier λ 2 represents the marginal impact of changes in the comprehensive flexibility index on system energy efficiency. Specifically, λ 2 The value of represents the change in total carbon emissions caused by a one-unit increase in the comprehensive flexibility index. 2 >0, increasing the unit comprehensive flexibility index will reduce the system energy efficiency λ 2 , the system has to sacrifice some energy efficiency in order to meet the flexibility requirements; if λ 2 <0, improving the unit comprehensive flexibility index will increase the system energy efficiency by λ 2 .

[0138] The comprehensive flexibility index Ftotal As the objective function, the specific process is:

[0139] S75, Lagrange multiplier λ 1 represents the marginal impact of changes in the total carbon emissions constraint on system energy efficiency. Specifically, λ 1 The value of represents the change in total carbon emissions caused by a one-unit improvement in system energy efficiency. 1 >0, increasing total carbon emissions will reduce system energy efficiency λ 1 ; if λ 1 <0, increasing total carbon emissions will increase system energy efficiency λ 1 .

[0140] S76, Lagrange multiplier λ 2 represents the marginal impact of changes in system energy efficiency constraints on system energy efficiency. Specifically, λ 2 The value of represents the change in total carbon emissions caused by a one-unit improvement in system energy efficiency. 2 >0, improving system energy efficiency will reduce system energy efficiency λ 2 , the system has to sacrifice some flexibility in order to meet energy efficiency requirements; if λ 2 <0, improving the unit system energy efficiency will increase the comprehensive flexibility index by λ 2 .

[0141] The focus of this method is to reveal the synergistic relationship among the three indicators of "energy efficiency-carbon-flexibility" through the definition of the indicators and analysis of the synergistic mechanism of "energy efficiency-carbon-flexibility", which will help guide the dynamic storage-release switching strategy of Carnot batteries and the multi-energy complementary operation optimization of integrated energy systems.

[0142] The present invention has the following beneficial effects:

[0143] (1) Existing research has not been sufficient in describing the dimension of flexible operation and indices calculation methods, and the understanding of the synergistic mechanism of "energy efficiency-carbon-flexibility" is not clear enough. This invention establishes the "energy efficiency-carbon-flexibility" index, and clarifies the flexibility of energy storage and release, multi-energy complementarity and energy flow transport of the integrated energy system based on Carnot batteries.

[0144] (2) Based on the “energy efficiency-carbon-flexibility” index, the present invention uses Lagrange multipliers and KKT conditions to explore the “energy efficiency-carbon-flexibility” synergistic mechanism, and can identify the operating mode with significant gain or attenuation of the “energy efficiency-carbon-flexibility” index. In particular, the method of the present invention can obtain the maximum energy efficiency (including Optimization strategies to improve efficiency, minimize carbon emissions, and enhance system flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0145] Figure 1Shown is a flow chart of the "energy efficiency-carbon-flexibility" collaborative analysis method of the present invention. DETAILED DESCRIPTION

[0146] The specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. It should be pointed out that the embodiments are only specific explanations of the invention and should not be regarded as limitations of the invention. The purpose of the embodiments is to enable those skilled in the art to better understand and reproduce the technical solutions of the present invention. The protection scope of the present invention shall still be based on the scope defined by the claims.

[0147] like Figure 1 As shown, this embodiment provides a "energy efficiency-carbon-flexibility" collaborative analysis method for an integrated energy system containing a Carnot battery, and the method is:

[0148] S1, calculate the energy efficiency of the comprehensive energy system (including efficiency);

[0149] The specific process is:

[0150] S11, electricity as a secondary energy source, ValueEx electric Equal to its energy value E electric , that is, Ex electric =E electric .

[0151] S12, Steam ValueEx steam The temperature needs to be considered and calculated using the thermodynamic formula:

[0152] Ex steam =hT 0 s

[0153] Where h is the specific enthalpy, T 0 is the ambient temperature and s is the specific entropy.

[0154] S13, compressed air ValueEx air The pressure and temperature need to be considered:

[0155]

[0156] Where R is the gas constant, P is the air pressure, P 0 is the ambient pressure, and k is the specific heat ratio.

[0157] S14, all input and output energy The total system input is obtained by summing the values. Value and system output total value;

[0158] S15, system energy efficiency is the total output Value and input total The ratio of the values ​​reflects the efficiency of energy conversion and utilization of the system under specific boundary conditions, and takes into account the quality of input and output energy. The calculation method is as follows:

[0159]

[0160] S2, determine the types of activities that should be included in carbon accounting (determined according to specific circumstances), and select carbon emission factors based on industry standards within the carbon accounting boundary to calculate the system's carbon emissions;

[0161] The specific process is:

[0162] For each fossil fuel, direct carbon emissions are calculated based on its consumption and carbon emission factor. The calculation method is:

[0163]

[0164] Among them, E fuel is the total carbon emissions from fuel combustion, is the consumption of the i-th energy source, is the carbon emission factor of the i-th energy source, in kgCO 2 e / kg.

[0165] The carbon emissions calculation method is as follows:

[0166] E GHG =E en +E tran +E mat +E dir +E dis -R

[0167] E en =E fuel +E ele +E heat

[0168] Among them, E GHG is the total emission, E en Carbon emissions from energy consumption, E tran is the carbon emissions from transportation, E mat is the carbon emission of consumed materials, E dir For direct CO 2 Form of emission; E dis is the emission from the waste treatment process, R is CO 2 Recovery amount, E ele E is the emissions from purchased net electricity; heat Emissions from net purchased heat.

[0169] According to the production characteristics of the integrated energy system, the types of activities for carbon emission accounting can be changed according to actual conditions (see Table 1 for details).

[0170] Table 1

[0171]

[0172] S3, calculate the flexibility index of “equipment-energy flow-system”;

[0173] The specific process of establishing the flexibility quantitative model and calculating the indicators is as follows:

[0174] S31, define the system response time constant (τ), the response speed is expressed by the inverse of the time constant:

[0175]

[0176] S32, load tracking error (∈ tracking ) is used to measure the load tracking capability of the system within a certain period of time, and is calculated by the difference between the system output power and the load demand power:

[0177]

[0178] Where P output is the system output power, P demand The power demanded by the load.

[0179] Load following capability of integrated energy systems F tracking Defined as the inverse of the load following error:

[0180]

[0181] S33, define energy conversion efficiency (η conversion ) and conversion time (t conversion ) is used to measure the flexibility of energy scheduling. The energy conversion efficiency calculation method is:

[0182]

[0183] Among them, E out is the output energy, E in For input energy.

[0184] Energy dispatch flexibility index F scheduling It can be expressed as:

[0185]

[0186] S34, Carnot battery energy storage conversion efficiency η storage That is the energy storage conversion efficiency index Fstorage :

[0187] F storage =η storage

[0188]

[0189] Among them, Q released is the heat energy released from the heat storage medium by the Carnot battery, Q stored is the thermal energy initially stored in the Carnot battery.

[0190] S35, actual utilization rate of Carnot battery energy storage capacity U capacity That is the energy storage capacity utilization index F capacity :

[0191] F capacity =U capacity

[0192]

[0193] S36, by taking a weighted average of five indicators, namely, response speed, load tracking capability, energy dispatch flexibility, energy storage conversion efficiency and energy storage capacity utilization, obtains a comprehensive flexibility score. The weights can be adjusted according to specific application scenarios and needs:

[0194] F total =ω 1 ·F response +ω 2 ·F tracking +ω 3 ·F scheduling +ω 4 ·F storage +ω 5 ·F capacity

[0195] Among them, ω 1 ,ω 2 ,ω 3 ,ω 4 ,ω 5 are the weight coefficients of response speed, load tracking capability, energy scheduling flexibility, energy storage conversion efficiency and energy storage capacity utilization, satisfying ω 1 +ω 2 +ω 3 +ω 4 +ω 5 =1.

[0196] S4, establish an optimization problem for the three indicators established in the previous steps. efficiency), carbon emissions, and flexibility as the objective function, and incorporate the remaining indicators into the constraint equation;

[0197] The specific process is:

[0198] S41, in this example, the total carbon emissions E GHG As an example of the objective function, the system energy efficiency η ex and comprehensive flexibility F total As constraints, the optimization problem is established as follows:

[0199] minE GHG

[0200] Subject to: ex ≥η ex,min , F total ≥F total,min

[0201] Among them, η ex,min is the lower limit of system energy efficiency, F total,min is the lower limit of comprehensive flexibility;

[0202] S42, the system energy efficiency η ex As the objective function, the total carbon emissions E GHG and comprehensive flexibility F total As a constraint, establish the system energy efficiency η ex The optimization problem is as follows:

[0203] The system energy efficiency η ex As the objective function, the total carbon emissions E GHG and comprehensive flexibility F total As constraints, the optimization problem is established as follows:

[0204] maxη ex

[0205] Subject to:E GHG ≤E GHG,max , F total ≥F total,min

[0206] Among them, E GHG,max is the upper limit of total carbon emissions;

[0207] S43, the integrated flexibility F total As the objective function, the total carbon emissions E GHG and system energy efficiency η ex As constraints, the optimization problem is established as follows:

[0208] maxF total

[0209] Subject to:E GHG ≤EGHG,max , η ex ≥η ex,min

[0210] S5, constructing the Lagrangian function, specifically adding the constraint conditions to the objective function through the Lagrangian multiplier;

[0211] The specific process is:

[0212] S51, the total carbon emissions E GHG As the objective function, construct the Lagrangian function:

[0213] L(E GHG ,η ex ,F total ,λ 1 ,λ 2 )=E GHG +λ 1 (η ex,min -η ex )+λ 2 (F total,min -F total )

[0214] S52, the system energy efficiency η ex As the objective function, construct the Lagrangian function:

[0215] L(E GHG ,η ex ,F total ,λ 1 ,λ 2 ) = η ex -λ 1 (E GHG -E GHG,max )-λ 2 (F total,min -F total )

[0216] S53, will integrate the flexibility of F total As the objective function, construct the Lagrangian function:

[0217] L(E GHG ,η ex ,F total ,λ 1 ,λ 2 )=F total -λ 1 (E GHG -E GHG,max )-λ 2 (η ex,min -η ex )

[0218] S6, establish the Karush-Kuhn-Tucker (KKT) condition, generalize the optimization problem involving equations handled by the Lagrange multiplication function to inequalities, and obtain a system of inequality equations containing Lagrange multipliers;

[0219] The total carbon emissions E GHG Taking the objective function as an example, the specific process is:

[0220] S61, the gradient of the Lagrangian function is zero (i.e. a first-order necessary condition):

[0221]

[0222] S62, the original constraint condition is established:

[0223] η ex ≥η ex,min (4)

[0224] F total ≥F total,min (5)

[0225] S63, non-negativity conditions for Lagrange multipliers:

[0226] λ 1 ≥0 (6)

[0227] λ 2 ≥0 (7)

[0228] S64, complementary relaxation condition:

[0229] λ 1 (η ex,min -η ex )=0 (8)

[0230] λ 2 (F total,min -F total )=0 (9)

[0231] The inequality equations containing Lagrange multipliers obtained in step S6 are analyzed:

[0232] From formula (1), we can get: It shows that the objective function is GHG The partial derivative of is 1.

[0233] From (2), we can get 1 =0, indicating that when the system energy efficiency reaches its minimum value, λ 1 =0.

[0234] From formula (3), we can get 2 =0, indicating that when the comprehensive flexibility reaches its minimum value, λ 2=0.

[0235] From equations (4) and (5), it can be concluded that the system energy efficiency and comprehensive flexibility must meet their lower limit constraints.

[0236] From equations (8) to (9) (complementary relaxation conditions), we can obtain that when η ex When λ is equal to its lower limit, 1 can be non-zero; when η ex When λ is greater than its lower limit, 1 = 0. Similarly, when F total When λ is equal to its lower limit, 2 can be non-zero; when F total When λ is greater than its lower limit, 2 =0.

[0237] S7, analyzing the influence of a unit change of any indicator on other indicators based on the inequality equation group containing Lagrange multipliers obtained in step S6;

[0238] The total carbon emissions E GHG As the objective function:

[0239] S71, Lagrange multiplier λ 1 represents the marginal impact of changes in system energy efficiency on total carbon emissions. Specifically, λ 1 The value of represents the change in total carbon emissions caused by a one-unit improvement in system energy efficiency. 1 >0, improving unit system energy efficiency will reduce total carbon emissions by λ 1 ; if λ 1 <0, improving unit system energy efficiency will increase total carbon emissions by λ 1 .

[0240] S72, Lagrange multiplier λ 2 represents the marginal impact of changes in the comprehensive flexibility index on total carbon emissions. Specifically, λ 2 The value of represents the change in total carbon emissions caused by a one-unit increase in the comprehensive flexibility index. 2 >0, increasing the unit comprehensive flexibility index will reduce the total carbon emissions by λ 2 ; if λ 2 <0, increasing the unit comprehensive flexibility index will increase the total carbon emissions by λ 2 .

[0241] Through the above analysis, the trade-offs and synergies between flexibility, carbon emissions and energy efficiency in the system can be determined, providing guidance for the optimization of the integrated energy system.

Claims

1. A "energy efficiency-carbon-flexibility" collaborative analysis method for an integrated energy system containing Carnot batteries, characterized in that: The method steps are: (1) Calculate the energy efficiency of the integrated energy system by the quality of multiple energy input and output values ​​within a given carbon accounting boundary; (2) Determine the types of activities that should be included in carbon accounting, select carbon emission factors based on industry standards within the carbon accounting boundaries, and calculate the carbon emissions of the integrated energy system; (3) Calculate the comprehensive flexibility index of "equipment-energy flow-system"; (4) Establishing an optimization problem for the three indicators of energy efficiency, carbon emissions and comprehensive flexibility index of the integrated energy system, specifically, taking energy efficiency, carbon emissions and any flexibility index as the objective function and incorporating the remaining indicators into constraints; (5) Constructing the Lagrangian function, specifically by adding the constraint conditions to the objective function through the Lagrangian multiplier; (6) Establish the KKT condition and generalize the optimization problem involving equations handled by the Lagrangian function to inequalities, thus obtaining a system of inequality equations containing Lagrangian multipliers; (7) Analyze the impact of a unit change in any indicator on other indicators based on a set of inequality equations containing Lagrange multipliers.

2. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 1 is characterized in that: In step (1), the calculation method of the energy efficiency of the integrated energy system is specifically as follows: (1.1) Electricity is a secondary energy source. ValueEx electric Equal to its energy value E electric , that is, Ex electric =E electric ; (1.2) Calculate the steam using thermodynamic formulas ValueEx steam : From steam =h-T0s Among them, h is specific enthalpy, T0 is ambient temperature, and s is specific entropy; (1.3) Calculate the compressed air ValueEx air , its pressure and temperature need to be considered: Where R is the gas constant, P is the air pressure, P0 is the ambient pressure, and k is the specific heat ratio; (1.4) All input and output energy The total system input is obtained by summing the values. ValueEx in,total and system output ValueEx out,total ; (1.5) Calculation system energy efficiency:

3. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 1 is characterized in that: In step (2), the carbon emission accounting method of the integrated energy system is: For each fossil fuel, direct carbon emissions are calculated based on its consumption and carbon emission factor, as follows: Among them, E fuel is the total carbon emissions from fuel combustion, is the consumption of the i-th energy source, is the carbon emission factor of the i-th energy source, in kgCO2e / kg; The carbon emissions of the integrated energy system are calculated as follows: AND GHG =And en +E tran +E mat +E dir +E dis -R AND en =And fuel +E ele +E heat Among them, E GHG is the total emission, E en Carbon emissions from energy consumption, E tran is the carbon emissions from transportation, E mat is the carbon emission of consumed materials, E dir E is the direct CO2 emission; dis is the emission from the waste treatment process, R is the CO2 recovery, E ele E is the emissions from purchased net electricity; heat Emissions from net purchased heat.

4. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 1 is characterized in that: The specific process of step (3) is as follows: (3.1) Define the system response time constant τ, and use the inverse of the time constant to express the response speed: (3.2) Define the load following capability F of the integrated energy system tracking is the load tracking error ∈ tracking The reciprocal of: Through the system output power P output and load demand power P demand The load tracking error is calculated by the difference between Wherein, T represents time; (3.3) Utilization of energy conversion efficiency η conversion and conversion time t conversion To calculate the energy dispatch flexibility F scheduling : Among them, E out is the output energy, E in is the input energy; (3.4) Energy storage conversion efficiency η of Carnot battery storage The energy storage conversion efficiency F storage : F storage =the storage (3.5) Actual utilization rate of Carnot battery energy storage capacity U capacity The energy storage capacity utilization rate F capacity : F capacity =U capacity (3.6) The comprehensive flexibility index F is obtained by taking the weighted average of the five indicators of response speed, load tracking capability, energy dispatch flexibility, energy storage conversion efficiency and energy storage capacity utilization. total : F total =ω1·F response +ω2·F tracking +ω3·F scheduling +ω4·F storage +ω5·F capacity Among them, ω1, ω2, ω3, ω4, and ω5 are weight coefficients of response speed, load tracking capability, energy scheduling flexibility, energy storage conversion efficiency, and energy storage capacity utilization, respectively, and ω1+ω2+ω3+ω4+ω5=1.

5. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 1 is characterized in that: The step (4) specifically comprises: (4.1) The total carbon emissions E GHG As the objective function, the system energy efficiency η ex and comprehensive flexibility index F total As constraints, the optimization problem is established: minE GHG Subject to:η ex ≥η ex,min ,F total ≥F total,min Among them, η ex,min is the lower limit of system energy efficiency, F total,min is the lower limit of the comprehensive flexibility index; (4.2) The system energy efficiency η ex As the objective function, the total carbon emissions E GHG and comprehensive flexibility index F total As constraints, the optimization problem is established: maxi ex Subject to:E GHG ≤E GHG,max ,F total ≥F total,min Among them, E GHG,max is the upper limit of total carbon emissions; (4.3) The comprehensive flexibility index F total As the objective function, the total carbon emissions E GHG and system energy efficiency η ex As constraints, the optimization problem is established: maxF total Subject to:E GHG ≤E GHG,max ,η ex ≥η ex,min 。 6. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 1 is characterized in that: The step (5) is specifically as follows: (5.1) The total carbon emissions E GHG As the objective function, list the Lagrangian function and add the constraints to the objective function through the Lagrangian multiplier: L(E GHG ,or ex ,F total ,λ1,λ2)=E GHG +λ1(η ex,min -or ex )+λ2)F total,min -F total ) among them, λ1 and λ2 are Lagrange multipliers; (5.2) The system energy efficiency η ex As the objective function, list the Lagrangian function and add the constraints to the objective function through the Lagrangian multiplier: L(E GHG ,or ex ,F total ,λ1,λ2)=η ex -λ1(E GHG -E GHG,max )-λ2(F total,min -F total ) (5.3) The comprehensive flexibility F total As the objective function, list the Lagrangian function and add the constraints to the objective function through the Lagrangian multiplier: L(E GHG ,or ex ,F total ,λ1,λ2)=F total -λ1(E GHG -E GHG,max )-λ2(η ex,min -or ex )。 7. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 1 is characterized in that: The step (6) is specifically as follows: The total carbon emissions E GHG When the objective function is used, the KKT condition is established to generalize the optimization problem involving equations handled by the Lagrangian function to inequalities, and obtain an inequality equation system containing Lagrangian multipliers, which specifically includes the following steps: (6.1) List the first-order necessary conditions for the gradient L of the Lagrangian function to be zero: (6.2) List the conditions under which the original constraints are satisfied: or ex ≥η ex,min (4) F total ≥F total,min (5) (6.3) List the non-negativity conditions of the Lagrange multiplier: λ1≥0 (6) λ2≥0 (7) (6.4) List the complementary relaxation conditions: λ1(η ex,min -or ex )=0 (8) λ2(F total,min -F total )=0 (9) Based on system energy efficiency η ex When the objective function is used, the KKT condition is established to generalize the optimization problem involving equations handled by the Lagrangian function to inequalities, and obtain an inequality equation system containing Lagrangian multipliers, which specifically includes the following steps: (6.5), we can list the first-order necessary conditions for the gradient L of the Lagrangian function to be zero: (6.6), the original constraint condition is satisfied: AND GHG ≤E GHG,max (13) F total ≥F total,min (14) (6.7), the non-negativity condition of the Lagrange multiplier: λ1≥0 (15) λ2≥0 (16) (6.8), complementary relaxation condition: λ1(E GHG -E GHG,max )=0 (17) λ2(F total,min -F total )=0 (18) The comprehensive flexibility index F total When the KKT condition is used as the objective function, the optimization problem involving equations handled by the Lagrangian function is extended to inequalities, and the method of obtaining the inequality equations containing Lagrangian multipliers is similar to the method of using the system energy efficiency η ex The method is similar when used as the objective function.

8. The "energy efficiency-carbon-flexibility" collaborative analysis method of an integrated energy system containing Carnot batteries according to claim 7 is characterized in that: The step (7) is specifically: The total carbon emissions E GHG When used as the objective function, the inequality equations based on Lagrange multipliers analyze the impact of a unit change of any indicator on other indicators, as follows: (7.1) The Lagrange multiplier λ1 represents the marginal effect of changes in system energy efficiency on total carbon emissions; specifically, the value of λ1 represents the change in total carbon emissions caused by a one-unit increase in system energy efficiency; If λ1>0, improving the unit system energy efficiency will reduce the total carbon emissions by λ1; if λ1<0, improving the unit system energy efficiency will increase the total carbon emissions by λ1; (7.2) The Lagrange multiplier λ2 represents the marginal impact of the change in the comprehensive flexibility index on the total carbon emissions; specifically, the value of λ2 represents the change in total carbon emissions caused by a one-unit increase in the comprehensive flexibility index; If λ2>0, increasing the unit comprehensive flexibility index will reduce the total carbon emissions by λ2; if λ2<0, increasing the unit comprehensive flexibility index will increase the total carbon emissions by λ2; Based on system energy efficiency η ex When used as the objective function, the inequality equations based on Lagrange multipliers analyze the impact of a unit change of any indicator on other indicators, as follows: (7.3) The Lagrange multiplier λ1 represents the marginal effect of the change in total carbon emissions on the system energy efficiency. Specifically, the value of λ1 represents the change in total carbon emissions caused by a one-unit increase in system energy efficiency. If λ1>0, increasing total carbon emissions will reduce the system energy efficiency by λ1. If λ1<0, increasing total carbon emissions will increase the system energy efficiency by λ1. (7.4) The Lagrange multiplier λ2 represents the marginal impact of the change in the comprehensive flexibility index on the system energy efficiency. Specifically, the value of λ2 represents the change in total carbon emissions caused by a one-unit increase in comprehensive flexibility. If λ2>0, increasing the comprehensive flexibility index per unit will reduce the system energy efficiency by λ2. In order to meet the flexibility demand, the system has to sacrifice some energy efficiency. If λ2<0, increasing the comprehensive flexibility index per unit will increase the system energy efficiency by λ2. The comprehensive flexibility index F total When used as the objective function, the inequality equations based on Lagrange multipliers analyze the impact of a unit change of any indicator on other indicators, as follows: (7.5) The Lagrange multiplier λ1 represents the marginal impact of the change in the total carbon emission constraint on the system energy efficiency; Specifically, the value of λ1 represents the change in total carbon emissions caused by a one-unit increase in system energy efficiency; if λ1>0, increasing total carbon emissions will reduce system energy efficiency by λ1; if λ1<0, increasing total carbon emissions will increase system energy efficiency by λ1; (7.6) The Lagrange multiplier λ2 represents the marginal impact of the change of the system energy efficiency constraint on the system energy efficiency; Specifically, the value of λ2 represents the change in total carbon emissions brought about by a one-unit increase in system energy efficiency; if λ2>0, improving system energy efficiency will reduce the system energy efficiency by λ2, and the system will have to sacrifice some flexibility in order to meet energy efficiency requirements; if λ2<0, improving unit system energy efficiency will increase the comprehensive flexibility index by λ2.

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