Comprehensive energy system optimization operation method considering electricity market transaction

Abstract

The invention discloses a comprehensive energy system optimization operation method considering electricity market transaction. According to the method, a green certificate-carbon transaction interaction mechanism is comprehensively considered, P2G segmented operation is refined, and a heat-to-electricity ratio adjustable technology is adopted, so that an optimized operation target with minimum energy purchasing cost, carbon transaction cost, green certificate transaction cost and energy abandoning cost is constructed, segmented processing is performed on a traditional power-to-gas system, green hydrogen generated in the process is refined and utilized, and the energy utilization rate of the system is improved. Secondly, the heat-to-power ratio adjustable technology of combined heat and power generation and hydrogen fuel cell equipment is researched, the system flexibility is improved, and the energy abandoning cost is reduced; and finally, a green certificate-carbon transaction interaction mechanism is introduced, a linkage relationship between carbon emission transaction and green certificate transaction is established, and the new energy consumption rate and the renewable energy utilization rate are improved in a marketization form.

Description

Technical Field

[0001] The present invention belongs to the field of integrated energy system optimization and scheduling, and proposes a green hydrogen system optimization operation model that comprehensively considers the green certificate-carbon trading interaction mechanism, refines the P2G segmented operation, and the heat-to-electricity ratio adjustable technology. Background Art

[0002] With the growth of global energy demand and the increasing prominence of environmental problems, the supply of traditional fossil energy faces many challenges. Therefore, my country actively promotes the development and utilization of renewable energy, increases the proportion of renewable energy electricity, and reduces the consumption of traditional fossil energy. The power-to-gas (P2G) integrated energy system has established a multi-energy complementary architecture covering refrigeration, heating, power supply and gas, which can provide users in the system with diverse energy supply needs. During its operation, it involves the production and utilization of multiple energy sources, which is easy to cause energy cascade loss and low utilization rate. The diversity of energy supply demand also puts forward high requirements on the flexible absorption capacity of the P2G system.

[0003] In order to promote the system to actively save energy and reduce emissions and promote the marketization of renewable energy, it is required to implement the Carbon Emission Trading (CET) mechanism and the Green Certificate Trade (GCT) mechanism. At present, my country's exploration of the green certificate and carbon trading market is still in its early stages. The supply and demand relationship between market participants is difficult to balance, and the flexibility of cooperation between GCT and other power markets is relatively poor. Summary of the invention

[0004] In summary, when the existing technology uses P2G to promote wind power consumption, it ignores the potential benefits of its detailed segmented production, resulting in a large energy ladder loss; the advantages of adjustable heat-to-electricity ratio technology in the cogeneration link are rarely considered. At the same time, the interactive mechanism between green certificate trading and carbon trading needs to be studied urgently. In view of the shortcomings of the existing methods, the present invention comprehensively considers the green certificate-carbon trading interactive mechanism, refines the P2G segmented operation and the adjustable heat-to-electricity ratio technology, and constructs an optimized operation target with the minimum purchase energy cost, carbon trading cost, green certificate trading cost, and abandoned energy cost. A green certificate-carbon trading interactive optimization operation method for a comprehensive energy system considering adjustable heat-to-electricity ratio and P2G segmented operation is proposed. This method processes the traditional power-to-gas system in segments, refines the green hydrogen produced during the utilization process, and then studies the adjustable heat-to-electricity ratio technology of cogeneration and hydrogen fuel cell equipment to improve system flexibility and reduce abandoned energy costs; finally, the green certificate-carbon trading interactive mechanism is introduced to establish a linkage relationship between carbon emission trading and green certificate trading, so as to improve the new energy consumption rate and renewable energy utilization rate in a market-oriented manner.

[0005] In order to achieve the above invention objectives, a method for optimizing the operation of an integrated energy system considering power market transactions comprises the following steps:

[0006] Step 1: Build a P2G segmented and detailed operation architecture.

[0007] Step 2: Establish a combined heat and power unit model based on an adjustable heat-to-electricity ratio. Introduce the adjustable heat-to-electricity ratio technology based on the coordinated operation of gas combined heat and power equipment CHP and hydrogen fuel cell equipment HFC. Consider the P2G segmented and refined operation architecture of step 1, and comprehensively construct the IES optimization operation model for electric hydrogen production. Enable IES to adapt to the electric and thermal load demand in different time periods, flexibly adjust the output strategy according to the time-of-use electricity price, and improve the economic efficiency of system operation.

[0008] Step 3: Build a joint trading market framework for carbon trading CET and green certificate trading GCT based on the green certificate-carbon trading interaction mechanism.

[0009] Step 4: Based on the carbon trading CET and green certificate trading GCT joint trading market framework established above and the IES optimization operation model of hydrogen production by electricity, construct the objective function with the lowest total operating cost, and comprehensively consider the renewable energy output constraints, grid power interaction constraints, energy storage constraints, equipment operation constraints, power balance constraints and market trading constraints to construct an integrated energy system optimization operation model with embedded adjustable heat-to-electricity ratio and P2G segmented operation constraints under the carbon-green certificate trading mechanism. Solve the integrated energy system optimization operation model to achieve green certificate-carbon trading interaction optimization.

[0010] Furthermore, the specific method of step 1 is as follows:

[0011] The traditional power-to-gas (P2G) process is divided into two stages by using the combined operation of hydrogen fuel cells HFC, electrolyzers EL, and methane reactors MR. In the first stage, the input electrical energy is converted into hydrogen energy through EL, and the CO2 generated in the system is collected and stored through the CO2 collection device. In the second stage, part of the hydrogen energy is input into MR and CO2 to synthesize natural gas as an intermediate amount in the P2G process, and the other part is directly converted into electricity and heat energy by HFC, and the remaining hydrogen energy is stored in the hydrogen storage tank. The above equipment model is described as follows:

[0012] 1) EL device model:

[0013]

[0014] Where: P e,EL (t) is the electric energy input to EL during period t; is the hydrogen energy output by EL during period t; η EL is the energy conversion efficiency of EL; They are the upper and lower limits of the electric energy of the input EL respectively; They are the upper and lower limits of EL climbing respectively.

[0015] 2)MR device model:

[0016]

[0017] Where: P is the hydrogen energy of MR input during period t; MR,g (t) is the natural gas power output by MR during period t; η MR is the energy conversion efficiency of MR; are the upper and lower limits of hydrogen energy input to MR, respectively; They are the upper and lower limits of MR climbing respectively.

[0018] Furthermore, the specific method of step 2 is as follows:

[0019] The principle of the adjustable heat-to-electricity ratio technology is to adjust the power generation in real time by controlling the air intake of the generator set. At the same time, the supplementary combustion boiler adjusts the heat supply by controlling the supplementary combustion amount; thus, the CHP system can be flexibly adjusted according to actual needs to maximize energy utilization efficiency. Its working model is:

[0020]

[0021] Where: P g,CHP (t) is the natural gas power input to CHP during period t; P CHP,e (t), P CHP,h (t) are the electrical and thermal power output of CHP in period t, respectively; are the efficiency of natural gas conversion into electricity and heat energy, respectively; They are the upper and lower limits of natural gas power input to CHP respectively; They are the upper and lower limits of CHP power ramping respectively; They are the upper and lower limits of the thermal-to-electricity ratio of CHP respectively.

[0022] Similarly, HFC burns hydrogen to generate electricity and heat. By changing the cooling circulating water flow rate, the heat-to-electricity ratio can be adjusted according to the real-time electric and thermal load conditions. The working model is:

[0023]

[0024] Where: P is the hydrogen power input to HFC during period t; HFC,e (t), P HFC,h (t) are the electrical and thermal power output of HFC in period t; η HFC,e , η HFC,h are the efficiency of HFC conversion into electricity and heat, respectively; They are the upper and lower limits of hydrogen energy for input HFC respectively; They are the upper and lower limits of HFC climbing respectively; They are the upper and lower limits of the heat-to-electricity ratio of HFC respectively.

[0025] The above-established model is embedded into the P2G segmented and refined operation model in step one to obtain the IES optimized operation model of hydrogen production by electricity.

[0026] Furthermore, the specific method of step three is as follows:

[0027] 1) GCT mechanism. GCT can be used to verify and track the power generation and source of renewable energy. The GCT mechanism converts the actual consumption of renewable energy power generation into green certificates, referred to as green certificates. The consumption quota of renewable energy is carried out by relevant regulatory authorities. Enterprises that fail to meet the quota need to purchase green certificates from the market to meet the quota indicators. On the contrary, they can convert their own renewable energy power generation into green certificates for sale. This will constrain IES's consumption of renewable energy. The calculation method of green certificate transaction cost is:

[0028]

[0029] Where: C GCT is the transaction cost of green certificates; λ is the unit price of green certificates; ρ is the green certificate quota coefficient that IES needs to hold; δ is the quantitative coefficient of renewable energy power generation converted into green certificates; P PV (t), P WT (t) are the output power of distributed photovoltaic and wind power at time t; P e,Load (t) is the electrical load at time t; P HFC,e (t) is the electric power generated by the HFC unit consuming hydrogen at time t.

[0030] 2) CET mechanism. The carbon trading mechanism is a market mechanism based on carbon emission rights. Producers formulate reasonable production plans based on the carbon quotas issued by regulatory authorities. When the actual carbon emissions are higher than the carbon emission quotas they have, they need to purchase carbon emission rights in the carbon trading market. Otherwise, they can sell the remaining carbon emission quotas in the market. The calculation process of carbon emission costs can be expressed as:

[0031]

[0032] Where: C CET is the carbon emission transaction cost; σ is the unit carbon transaction price; k is the step length; γ is the unit price growth rate; B st The carbon emission trading amount.

[0033] The power purchased by the integrated energy system from the upper level is thermal power generation. According to the baseline method, the power purchase, CHP, and GB in the energy system are the sources of carbon emissions. The carbon emissions can be specifically expressed as:

[0034]

[0035] Where: P e,buy (t) is the amount of electricity purchased by the system from the power grid during period t; B stg is the carbon emissions generated; B s is the allocated carbon emissions; β1 is the carbon emissions generated per unit power; β2 is the carbon emissions allocated per unit power; B MR is the actual amount of CO2 absorbed by MR; ω is the CO2 absorption coefficient during the MR hydrogen-to-natural gas conversion process.

[0036] 3) GCT-CET interactive mechanism. Through the green certificate trading situation, we can obtain information on the generation and consumption of new energy in the system. Therefore, by comparing the carbon emissions of new energy and traditional thermal power generation, we can calculate the carbon emissions reduced by the green electricity used by the enterprise compared with traditional electricity. Through the establishment of the green certificate-carbon trading interactive mechanism, IES can convert part of the green certificate into carbon emission quotas while obtaining it. The specific conversion calculation method is:

[0037]

[0038] Where: B green is the carbon emission quota obtained by converting green certificates for renewable energy power generation; κ is the conversion coefficient.

[0039] In the normal trading mode of the green certificate market and the carbon trading market, the GCT-CET interaction mechanism is used to form a link between the two markets, thereby building a joint trading market framework for carbon trading CET and green certificate trading GCT.

[0040] Furthermore, the specific method of step 4 is as follows:

[0041] An optimized operation model of an integrated energy system with an embedded adjustable heat-to-electricity ratio and P2G segmented operation constraints under the carbon-green certificate trading mechanism is constructed, including two parts: objective function and operation constraints.

[0042] Based on the above CET and GCT joint trading market framework, the carbon trading cost and green certificate trading cost are obtained; based on the IES optimization operation model of hydrogen production by electricity, the IES energy purchase cost and energy abandonment cost are obtained. Comprehensive consideration of IES energy purchase cost Cost of curtailed energy Carbon trading costs C CET and green certificate transaction cost C GCT , the objective function to construct the lowest total operating cost F is as follows:

[0043]

[0044] in:

[0045] Energy purchase cost for:

[0046]

[0047] Where: is the interactive electricity price between the power grid and the upper grid at time t, P is the price of gas purchased from the upper gas network at time t. g,buy (t) is the gas purchase volume from the upper-level gas network during period t.

[0048] Cost of curtailed energy for

[0049]

[0050] Where: WT P is the penalty cost for unit wind curtailment; WT,cut (t) is the wind power abandoned during period t; δ PV P is the penalty cost for unit abandonment; PV,cut (t) is the abandoned optical power in period t.

[0051] By establishing various operating constraints as boundary conditions for solving the objective function, the proposed constraints include:

[0052] 1) Renewable energy output constraints:

[0053]

[0054] Where: P WT (t) is the wind power output power in period t; is the upper limit of wind power output power; P PV (t) is the photovoltaic output power during period t; is the upper limit of photovoltaic output power.

[0055] 2) Grid interaction power constraints:

[0056]

[0057] Where: P grid (t) is the power exchanged with the upper power grid at time t, It is the maximum power interacting with the upper grid at time t.

[0058] 3) Energy storage operation constraints:

[0059] Since the models of electric, thermal, gas and hydrogen energy storage devices are similar, the constraints of energy storage devices are modeled uniformly.

[0060]

[0061] Where: are the charging and discharging powers of the nth type of energy storage device during period t respectively; The maximum single charge and discharge power of the nth energy storage device; are binary variables, which are the charging and discharging state parameters of the nth energy storage device in period t, P ES,n (t) is the final output power of the nth energy storage device; are the charging and discharging efficiencies of the nth energy storage device; S n (t) is the real-time capacity of the nth energy storage device in period t; is the rated capacity of the nth type of energy storage device; They are respectively the upper and lower limits of the capacity of the nth type of energy storage device.

[0062] 4) Constraints on purchasing power:

[0063]

[0064] Where: These are the gas and electricity purchase limits for each time period.

[0065] 5) Electric power balance constraints:

[0066] P e,buy (t) = P e,Load (t)+P e,EL (t)+P ES,e (t)-P WT (t)-P HFC,e (t) (16)

[0067] Where: P ES,e (t) is the power input into the storage device during the period t.

[0068] 6) Gas power balance constraints:

[0069] P g,buy (t) = P g,Load (t)+P ES,g (t)+P g,CHP (t)+P g,GB (t)+P MR,g (t) (17)

[0070] Where: P g,Load (t) is the gas load in the period t; P ES,g (t) is the power input into the storage device during the period t.

[0071] 7) Thermal power balance constraints:

[0072] P HFC,h (t)+P CHP,h (t)+P GB,h (t) = P h,Load (t)+P ES,h (t)(18)

[0073] Where: P h,Load (t) is the heat load in the period t; P ES,h (t) is the power input into the thermal storage device during period t.

[0074] 8) Hydrogen balance constraints:

[0075]

[0076] Where: is the power input into the hydrogen storage device during period t.

[0077] 9) Carbon market constraints:

[0078]

[0079] Where: C CET,i and C CET,o are the total amount of carbon emission rights purchased and sold by IES to the external carbon market; and They are respectively the stock of carbon emission rights in the market and the upper limit of the shortfall.

[0080] 10) Green Certificate Market Constraints:

[0081]

[0082] Where: C GCT,i and C GCT,o The numbers of green certificates purchased and sold by IES from the green certificate market; and are the stock of green certificates in the market and the upper limit of the shortage; B tra B is the number of green certificates converted into carbon quotas; GCT The number of green certificates traded in the market.

[0083] The YALMIP toolbox and CPLEX solver are used on the MATLAB software platform to solve the optimal operation model of the integrated energy system.

[0084] The beneficial effects of the present invention are as follows:

[0085] The P2G segmented and refined operation architecture is used to reduce the cascade loss of hydrogen energy. Through the cogeneration of heat and power by regulating the flow rate of heat dissipation circulating water and the adjustable heat-to-electricity ratio technology of hydrogen fuel cell equipment, IES can adapt to the changes in electric and thermal load demand in different time periods. Secondly, the green certificate-carbon trading interaction mechanism improves the absorption capacity of renewable energy on the basis of constraining the system's carbon emissions. The conversion mechanism of green certificates and carbon emission rights increases the investment flexibility between the two markets and encourages the production and absorption of clean energy, thereby achieving more efficient resource allocation and more comprehensive environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 It is a time-of-use electricity and gas price chart;

[0087] Figure 2 Forecast output and load curves for renewable energy;

[0088] Figure 3 This is a system structure block diagram of an embodiment of the present invention;

[0089] Figure 4 This is a framework diagram of the operation of the green certificate-carbon trading interaction mechanism of an embodiment of the present invention;

[0090] Figure 5 It is the thermoelectric ratio curve of HFC and CHP;

[0091] Figure 6 This is an energy flow diagram. DETAILED DESCRIPTION

[0092] In combination with the accompanying drawings and embodiments, the present invention establishes an integrated energy system optimization operation method considering power market transactions, and the implementation process is as follows:

[0093] Step 1: Build a segmented and refined P2G operation architecture. The traditional P2G process converts input electrical energy into natural gas through EL and MR equipment, and a large amount of hydrogen is produced in the intermediate process. Hydrogen is a green, zero-carbon, flexible and efficient secondary energy source. Therefore, segmenting the power-to-gas process can make full use of the hydrogen energy in the process.

[0094] The traditional power-to-gas (P2G) process is divided into two stages by using the combined operation of hydrogen fuel cells HFC, electrolyzers EL, and methane reactors MR. In the first stage, the input electrical energy is converted into hydrogen energy through EL, and the CO2 generated in the system is collected and stored through a CO2 collection device. In the second stage, part of the hydrogen energy is input into MR as an intermediate amount of the P2G process to synthesize natural gas with CO2, and the other part is directly converted into electricity and heat energy by HFC, and the remaining hydrogen energy is stored in a hydrogen storage tank. Compared with synthesizing methane first and then burning it through GB and CHP, the direct conversion of hydrogen energy through HFC reduces the step-by-step loss of energy. In addition, the combustion efficiency of hydrogen is higher than that of natural gas, and no carbon emissions are generated. The above equipment model is described as follows:

[0095] 1) EL device model:

[0096]

[0097] Where: P e,EL (t) is the electric energy input to EL during period t; is the hydrogen energy output by EL during period t; η EL is the energy conversion efficiency of EL; They are the upper and lower limits of the electric energy of the input EL respectively; They are the upper and lower limits of EL climbing respectively.

[0098] 2)MR device model:

[0099]

[0100] Where: P is the hydrogen energy of MR input during period t; MR,g (t) is the natural gas power output by MR during period t; η MR is the energy conversion efficiency of MR; are the upper and lower limits of hydrogen energy input to MR, respectively; They are the upper and lower limits of MR climbing respectively.

[0101] Step 2: Establish a combined heat and power unit model based on an adjustable heat-to-electricity ratio. Introduce the adjustable heat-to-electricity ratio technology based on the coordinated operation of gas combined heat and power equipment CHP and hydrogen fuel cell equipment HFC. Consider the P2G segmented and refined operation architecture of step 1, and comprehensively construct the IES optimization operation model for electric hydrogen production. Enable IES to adapt to the electric and thermal load demand in different time periods, flexibly adjust the output strategy according to the time-of-use electricity price, and improve the economic efficiency of system operation.

[0102] The principle of the adjustable heat-to-electricity ratio technology is to adjust the power generation in real time by controlling the air intake of the generator set. At the same time, the supplementary combustion boiler adjusts the heat supply by controlling the supplementary combustion amount; thus, the CHP system can be flexibly adjusted according to actual needs to maximize energy utilization efficiency. Its working model is:

[0103]

[0104] Where: P g,CHP (t) is the natural gas power input to CHP during period t; P CHP,e (t), P CHP,h (t) are the electrical and thermal power output of CHP in period t, respectively; are the efficiency of natural gas conversion into electricity and heat energy, respectively; They are the upper and lower limits of natural gas power input to CHP respectively; They are the upper and lower limits of CHP power ramping respectively; They are the upper and lower limits of the thermal-to-electricity ratio of CHP respectively.

[0105] Similarly, HFC burns hydrogen to generate electricity and heat. The traditional model has a fixed heat-to-electricity ratio, and generally operates in the "heat determines electricity" or "electricity determines heat" mode, with poor operating flexibility. By changing the flow rate of the heat dissipation circulating water, the heat-to-electricity ratio can be adjusted according to the real-time electric and thermal load conditions. The working model is:

[0106]

[0107] Where: P is the hydrogen power input to HFC during period t; HFC,e (t), P HFC,h (t) are the electrical and thermal power output of HFC in period t; η HFC,e , η HFC,h are the efficiency of HFC conversion into electricity and heat, respectively; They are the upper and lower limits of hydrogen energy for input HFC respectively; They are the upper and lower limits of HFC climbing respectively; They are the upper and lower limits of the heat-to-electricity ratio of HFC respectively.

[0108] The above-established model is embedded into the P2G segmented and refined operation model in step one to obtain the IES optimized operation model of hydrogen production by electricity.

[0109] Step 3: Based on the green certificate-carbon trading interactive mechanism, a joint trading market framework for carbon trading CET and green certificate trading GCT is established. Information on new energy generation and consumption in the integrated energy system is obtained through green certificate trading. By comparing the carbon emissions of new energy and traditional thermal power generation, the carbon emissions reduced by the green electricity used by the enterprise compared with traditional electricity are calculated. Under the green certificate-carbon trading interactive mechanism, IES can convert the excess into carbon emission quotas while obtaining green certificates.

[0110] In order to improve the richness and flexibility of the power market, the present invention constructs a joint trading market framework of CET and GCT. The combined effect of the two markets can better penetrate the output of renewable energy into the system. The specific trading mechanism framework proposed in the present invention is as follows: Figure 4 shown.

[0111] 1) GCT mechanism. GCT can be used to verify and track the power generation and source of renewable energy. The GCT mechanism converts the actual consumption of renewable energy power generation into green certificates, referred to as green certificates. The consumption quota of renewable energy is carried out by relevant regulatory authorities. Enterprises that fail to meet the quota need to purchase green certificates from the market to meet the quota indicators. On the contrary, they can convert their own renewable energy power generation into green certificates for sale. This will constrain IES's consumption of renewable energy. The calculation method of green certificate transaction cost is:

[0112]

[0113] Where: C GCT is the transaction cost of green certificates; λ is the unit price of green certificates; ρ is the green certificate quota coefficient that IES needs to hold; δ is the quantitative coefficient of renewable energy power generation converted into green certificates; P PV (t), P WT (t) are the output power of distributed photovoltaic and wind power at time t; P e,Load (t) is the electrical load at time t; P HFC,e (t) is the electric power generated by the HFC unit consuming hydrogen at time t.

[0114] 2) CET mechanism. The carbon trading mechanism is a market mechanism based on carbon emission rights. Producers formulate reasonable production plans based on the carbon quotas issued by regulatory authorities. When the actual carbon emissions are higher than the carbon emission quotas they have, they need to purchase carbon emission rights in the carbon trading market. Otherwise, they can sell the remaining carbon emission quotas in the market. The calculation process of carbon emission costs can be expressed as:

[0115]

[0116] Where: C CET is the carbon emission transaction cost; σ is the unit carbon transaction price; k is the step length; γ is the unit price growth rate; Bst The carbon emission trading amount.

[0117] The power purchased by the integrated energy system from the upper level is thermal power generation. According to the baseline method, the power purchase, CHP, and GB in the energy system are the sources of carbon emissions. The carbon emissions can be specifically expressed as:

[0118]

[0119] Where: P e,buy (t) is the amount of electricity purchased by the system from the power grid during period t; B stg is the carbon emissions generated; B s is the allocated carbon emissions; β1 is the carbon emissions generated per unit power; β2 is the carbon emissions allocated per unit power; B MR is the actual amount of CO2 absorbed by MR; ω is the CO2 absorption coefficient during the MR hydrogen-to-natural gas conversion process.

[0120] 3) GCT-CET interactive mechanism. Through the green certificate trading situation, we can obtain information on the generation and consumption of new energy in the system. Therefore, by comparing the carbon emissions of new energy and traditional thermal power generation, we can calculate the carbon emissions reduced by the green electricity used by the enterprise compared with traditional electricity. Through the establishment of the green certificate-carbon trading interactive mechanism, IES can convert part of the green certificate into carbon emission quotas while obtaining it. The specific conversion calculation method is:

[0121]

[0122] Where: B green is the carbon emission quota obtained by converting green certificates for renewable energy power generation; κ is the conversion coefficient.

[0123] In the normal trading mode of the green certificate market and the carbon trading market, the GCT-CET interaction mechanism is used to form a link between the two markets, thereby building a joint trading market framework for carbon trading CET and green certificate trading GCT. Participants can plan their investment level within this market framework, greatly improving market flexibility.

[0124] Step 4: Based on the carbon trading CET and green certificate trading GCT joint trading market framework established above and the IES optimization operation model of hydrogen production by electricity, construct the objective function with the lowest total operating cost, and comprehensively consider the renewable energy output constraints, grid power interaction constraints, energy storage constraints, equipment operation constraints, power balance constraints and market transaction constraints to construct an integrated energy system optimization operation model with embedded adjustable heat-to-electricity ratio and P2G segmented operation constraints under the carbon-green certificate trading mechanism. Solve the optimization operation model of the integrated energy system to achieve interactive optimization of green certificate-carbon trading. The specific operations are as follows:

[0125] An optimized operation model of an integrated energy system with an embedded adjustable heat-to-electricity ratio and P2G segmented operation constraints under the carbon-green certificate trading mechanism is constructed, including two parts: objective function and operation constraints.

[0126] Based on the above CET and GCT joint trading market framework, the carbon trading cost and green certificate trading cost are obtained; based on the IES optimization operation model of hydrogen production by electricity, the IES energy purchase cost and energy abandonment cost are obtained. Comprehensive consideration of IES energy purchase cost Cost of curtailed energy Carbon trading costs C CET and green certificate transaction cost C GCT , the objective function to construct the lowest total operating cost F is as follows:

[0127]

[0128] in:

[0129] Energy purchase cost for:

[0130]

[0131] Where: is the interactive electricity price between the power grid and the upper grid at time t, P is the price of gas purchased from the upper gas network at time t. g,buy (t) is the gas purchase volume from the upper-level gas network during period t.

[0132] Cost of curtailed energy for

[0133]

[0134] Where: WT P is the penalty cost for unit wind curtailment; WT,cut (t) is the wind power abandoned during period t; δ PV P is the penalty cost for unit abandonment; PV,cut (t) is the abandoned optical power in period t.

[0135] By establishing various operation constraints as boundary conditions for solving the objective function, the constraints proposed in the present invention include:

[0136] 1) Renewable energy output constraints:

[0137]

[0138] Where: P WT (t) is the wind power output power in period t; is the upper limit of wind power output power; P PV (t) is the photovoltaic output power during period t; is the upper limit of photovoltaic output power.

[0139] 2) Grid interaction power constraints:

[0140]

[0141] Where: P grid (t) is the power exchanged with the upper power grid at time t, It is the maximum power interacting with the upper grid at time t.

[0142] 3) Energy storage operation constraints:

[0143] Since the models of electric, thermal, gas and hydrogen energy storage devices are similar, the constraints of energy storage devices are modeled uniformly.

[0144]

[0145] Where: are the charging and discharging powers of the nth type of energy storage device during period t respectively; The maximum single charge and discharge power of the nth energy storage device; are binary variables, which are the charging and discharging state parameters of the nth energy storage device in period t, P ES,n (t) is the final output power of the nth energy storage device; are the charging and discharging efficiencies of the nth energy storage device; S n (t) is the real-time capacity of the nth energy storage device in period t; is the rated capacity of the nth type of energy storage device; They are respectively the upper and lower limits of the capacity of the nth type of energy storage device.

[0146] 4) Constraints on purchasing power:

[0147]

[0148] Where: These are the gas and electricity purchase limits for each time period.

[0149] 5) Electric power balance constraints:

[0150] P e,buy (t) = P e,Load (t)+P e,EL (t)+P ES,e (t)-P WT (t)-P HFC,e (t) (16)

[0151] Where: P ES,e (t) is the power input into the storage device during the period t.

[0152] 6) Gas power balance constraints:

[0153] P g,buy (t) = P g,Load (t)+P ES,g (t)+P g,CHP (t)+P g,GB (t)-P MR,g (t) (17)

[0154] Where: P g,Load (t) is the gas load in the period t; P ES,g (t) is the power input into the storage device during the period t.

[0155] 7) Thermal power balance constraints:

[0156] P HFC,h (t)+P CHP,h (t)+P GB,h (t) = P h,Load (t)+P ES,h (t) (18)

[0157] Where: P h,Load (t) is the heat load in the period t; P ES,h (t) is the power input into the thermal storage device during period t.

[0158] 8) Hydrogen balance constraints:

[0159]

[0160] Where: is the power input into the hydrogen storage device during period t.

[0161] 9) Carbon market constraints:

[0162]

[0163] Where: C CET,i and C CET,o are the total amount of carbon emission rights purchased and sold by IES to the external carbon market; and They are respectively the stock of carbon emission rights in the market and the upper limit of the shortfall.

[0164] 10) Green Certificate Market Constraints:

[0165]

[0166] Where: C GCT,i and C GCT,o The numbers of green certificates purchased and sold by IES from the green certificate market; and are the stock of green certificates in the market and the upper limit of the shortage; Btra B is the number of green certificates converted into carbon quotas; GCT The number of green certificates traded in the market.

[0167] The models established in the present invention are all mixed integer linear programming models. The YALMIP toolbox and CPLEX solver are used on the MATLAB software platform to solve the optimization operation model of the integrated energy system and realize the interactive optimization of green certificate-carbon trading.

[0168] Step 5: By setting up an experimental group and conducting comparative analysis with the green certificate-carbon trading interactive optimization operation scheme of the integrated energy system proposed in the present invention that takes into account the adjustable heat-to-electricity ratio and P2G segmented operation, the green and low-carbon nature and economic feasibility of the proposed model are verified.

[0169] The specific energy flow diagram of IES that integrates multiple energy sources in the present invention is as follows: Figure 6 As shown in the figure, a P2G segmented operation architecture based on an adjustable heat-to-electricity ratio is constructed. Figure 3 As shown in the figure, through the joint trading model of carbon trading and green certificate trading, renewable energy output can be better integrated into the system. The specific green certificate-carbon trading interactive mechanism operation framework is as follows Figure 4 Finally, in order to verify the coordinated optimization effect of the proposed model on the economic operation of the system and low-carbon green development, an IES in a park in Northwest China was selected as an example for verification. The scheduling cycle is 24 hours a day. The main parameters of the energy conversion equipment in the IES are shown in Table 1, and the parameters of each energy storage device are shown in Table 2.

[0170] Table 1 Energy conversion equipment parameters

[0171] equipment Capacity / kW Energy conversion efficiency / % Climbing constraint / kW EL 500 87 100 MR 250 60 50 HFC 250 95 50 GB 800 95 160 CHP 600 92 120

[0172] Table 2 Energy storage device parameters

[0173] equipment Capacity / kW Upper and lower capacity constraints / % Climbing constraint / kW Electricity Storage 450 90、10 90 Heat storage 500 90、10 100 Gas Storage 150 90、10 30 Hydrogen Storage 200 90、10 40

[0174] In order to reflect the flexible dispatching capability of the model, time-of-use electricity prices are adopted. The specific prices are as follows: Figure 1 As shown in the figure, the various loads and renewable energy output curves in the region are as follows: Figure 2 The scheduling models established in the present invention are all mixed integer linear programming models, and the IES optimization operation model is solved using the YALMIP toolbox and the CPLEX solver on the MATLAB software platform.

[0175] 2. Analysis of the interaction mechanism between green certificates and carbon trading

[0176] In order to verify the effectiveness of the green certificate-carbon trading interaction mechanism proposed in this invention, three operation schemes are set to compare and analyze the optimization results. Scheme 1: IES operation without considering the green certificate-carbon trading interaction mechanism; Scheme 2: IES operation with only carbon trading mechanism involved; Scheme 3: IES operation with green certificate-carbon trading interaction mechanism involved. The optimization comparison results of the three schemes are shown in Table 3.

[0177] Table 3 Comparison of benefits before and after considering the green certificate-carbon trading interaction mechanism

[0178]

[0179] 3. Energy efficiency analysis of P2G segmented operation with adjustable power-to-heat ratio

[0180] In order to verify the effectiveness of the P2G segmented refinement operation model proposed in this invention under the green certificate-carbon trading interaction mechanism, two other schemes are set up for comparative analysis with Scheme 3. Scheme 4: Use traditional P2G equipment to generate electricity in the system; Scheme 5: Replace traditional P2G equipment with a combination of EL, MR, and HFC equipment for segmented joint operation. The operation results under the two schemes are shown in Table 4. Among them, the specific system heat-to-electricity ratio adjustment is as follows Figure 5 shown.

[0181] Table 4 Comparison of benefits before and after P2G segmented operation

[0182]

[0183] The above contents are further detailed descriptions of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can also make several substitutions or modifications to these described embodiments without departing from the concept of the present invention, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention.

[0184] Parts of the present invention that are not described in detail belong to the well-known technologies of those skilled in the art.

Claims

1. A method for optimizing the operation of an integrated energy system considering power market transactions, characterized in that: The following steps are involved: Step 1: Build a P2G segmented and detailed operation architecture; Step 2: Establish a combined heat and power unit model based on adjustable heat-to-electricity ratio, introduce adjustable heat-to-electricity ratio technology based on the coordinated operation of gas combined heat and power equipment CHP and hydrogen fuel cell equipment HFC, consider the P2G segmented and refined operation architecture of step 1, and comprehensively construct an IES optimized operation model for electric hydrogen production, so that IES can adapt to the electric and thermal load demand in different time periods, flexibly adjust the output strategy according to the time-of-use electricity price, and improve the economic efficiency of system operation; Step 3: Construct a joint trading market framework for carbon trading CET and green certificate trading GCT based on the green certificate-carbon trading interaction mechanism; Step 4: Based on the carbon trading CET and green certificate trading GCT joint trading market framework established above and the IES optimization operation model of hydrogen production by electricity, construct the objective function of minimizing the total operating cost, and comprehensively consider the renewable energy output constraints, grid power interaction constraints, energy storage constraints, equipment operation constraints, power balance constraints and market transaction constraints to construct an integrated energy system optimization operation model with embedded adjustable heat-to-electricity ratio and P2G segmented operation constraints under the carbon-green certificate trading mechanism; solve the integrated energy system optimization operation model to realize the interactive optimization of green certificate-carbon trading.

2. A method for optimizing operation of an integrated energy system considering power market transactions according to claim 1, characterized in that: Step 1: The traditional power-to-gas (P2G) process is divided into two stages by using the combined operation of hydrogen fuel cells (HFC), electrolyzers (EL), and methane reactors (MR). In the first stage, the input electrical energy is converted into hydrogen energy through EL, and the CO2 generated in the system is collected and stored through a CO2 collection device. In the second stage, part of the hydrogen energy is input into MR as an intermediate amount in the P2G process to synthesize natural gas with CO2, and the other part is directly converted into electricity and heat energy by HFC, and the remaining hydrogen energy is stored in a hydrogen storage tank. The above equipment model is described as follows: 1) EL device model: Where: P e,EL (t) is the electric energy input to EL during period t; is the hydrogen energy output by EL during period t; η EL is the energy conversion efficiency of EL; They are the upper and lower limits of the electric energy of the input EL respectively; They are the upper and lower limits of EL climbing respectively; 2)MR device model: Where: P is the hydrogen energy of MR input during period t; MR,g (t) is the natural gas power output by MR during period t; η MR is the energy conversion efficiency of MR; are the upper and lower limits of hydrogen energy input to MR, respectively; They are the upper and lower limits of MR climbing respectively.

3. A method for optimizing operation of an integrated energy system considering power market transactions according to claim 2, characterized in that: The specific method of step 2 is as follows: The principle of the adjustable heat-to-power ratio technology is: by controlling the air intake of the generator set, the power generation is adjusted in real time; at the same time, the supplementary combustion boiler adjusts the heat supply by controlling the supplementary combustion process; thus, the CHP system can be flexibly adjusted according to actual needs to maximize energy utilization efficiency; Its working model is: Where: P g,CHP (t) is the natural gas power input to CHP during period t; P CHP,e (t), P CHP,h (t) are the electrical and thermal power output of CHP in period t, respectively; are the efficiency of natural gas conversion into electricity and heat energy, respectively; They are the upper and lower limits of natural gas power input to CHP respectively; They are the upper and lower limits of CHP power ramping respectively; They are the upper and lower limits of the thermal-to-electricity ratio of CHP, respectively; Similarly, HFC burns hydrogen to generate electricity and heat. By changing the cooling circulating water flow rate, the heat-to-electricity ratio can be adjusted according to the real-time electric and thermal load conditions. The working model is: Where: P is the hydrogen power input to HFC during period t; HFC,e (t), P HFC,h (t) are the electrical and thermal power output of HFC in period t, respectively; η HFC,e , η HFC,h are the efficiency of HFC conversion into electricity and heat, respectively; They are the upper and lower limits of hydrogen energy for input HFC respectively; They are the upper and lower limits of HFC climbing respectively; They are the upper and lower limits of the heat-to-power ratio of HFC respectively; The above-established model is embedded into the P2G segmented and refined operation model in step one to obtain the IES optimized operation model of hydrogen production by electricity.

4. A method for optimizing operation of an integrated energy system considering power market transactions according to claim 3, characterized in that: The specific method of step three is as follows: 1) GCT mechanism; GCT can be used to verify and track the power generation and source of renewable energy. The GCT mechanism converts the actual consumption of renewable energy power generation into green certificates, referred to as green certificates. The consumption quota of renewable energy is carried out by relevant regulatory authorities. Enterprises that fail to meet the quota need to purchase green certificates from the market to meet the quota indicators. On the contrary, they can convert their own renewable energy power generation into green certificates for sale; thereby constraining IES's consumption of renewable energy; the calculation method of green certificate transaction cost is: Where: C GCT is the transaction cost of green certificates; λ is the unit price of green certificates; ρ is the green certificate quota coefficient that IES needs to hold; δ is the quantitative coefficient of renewable energy power generation converted into green certificates; P PV (t), P WT (t) are the output power of distributed photovoltaic and wind power at time t; P e,Load (t) is the electrical load at time t; P HFC,e (t) is the electric power generated by the HFC device consuming hydrogen at time t; 2) CET mechanism; The carbon trading mechanism is a market mechanism based on carbon emission rights. Producers formulate reasonable production plans based on the carbon quotas issued by regulatory authorities. When the actual carbon emissions are higher than the carbon emission quotas they have, they need to purchase carbon emission rights in the carbon trading market. Otherwise, they can sell the remaining carbon emission quotas in the market. The calculation process of carbon emission costs can be expressed as: Where: C CET is the carbon emission transaction cost; σ is the unit carbon transaction price; k is the step length; γ is the unit price growth rate; B st is the carbon emission trading amount; The power purchased by the integrated energy system from the upper level is thermal power generation. According to the baseline method, the power purchase, CHP, and GB in the energy system are the sources of carbon emissions; the carbon emissions can be specifically expressed as: Where: P e,buy (t) is the amount of electricity purchased by the system from the power grid during period t; B stg is the carbon emissions generated; B s is the allocated carbon emissions; β1 is the carbon emissions generated per unit power; β2 is the carbon emissions allocated per unit power; B MR is the actual amount of CO2 absorbed by MR; ω is the CO2 absorption coefficient during the MR hydrogen-to-natural gas conversion process; 3) GCT-CET interactive mechanism: Through the green certificate trading situation, the information on the generation and consumption of new energy in the system can be obtained. Therefore, by comparing the carbon emissions of new energy and traditional thermal power generation, the carbon emissions reduced by the green electricity used by the enterprise compared with traditional electricity can be calculated. Through the established green certificate-carbon trading interactive mechanism, IES can convert part of the green certificate into carbon emission quotas at the same time as obtaining it. The specific conversion calculation method is as follows: Where: B green The carbon emission quota obtained by converting green certificates for renewable energy power generation; k is the conversion coefficient; In the normal trading mode of the green certificate market and the carbon trading market, the GCT-CET interaction mechanism is used to form a link between the two markets, thereby building a joint trading market framework for carbon trading CET and green certificate trading GCT.

5. A method for optimizing operation of an integrated energy system considering power market transactions according to claim 4, characterized in that: The specific method of step 4 is as follows: Construct an integrated energy system optimization operation model with an embedded adjustable heat-to-electricity ratio and P2G segmented operation constraints under the carbon-green certificate trading mechanism, including two parts: objective function and operation constraints; Based on the above CET and GCT joint trading market framework, the carbon trading cost and green certificate trading cost are obtained; based on the IES optimization operation model of hydrogen production by electricity, the IES energy purchase cost and energy abandonment cost are obtained; considering the IES energy purchase cost comprehensively Cost of curtailed energy Carbon trading costs C CET and green certificate transaction cost C GCT , the objective function to construct the lowest total operating cost F is as follows: in: Energy purchase cost for: Where: is the interactive electricity price between the power grid and the upper grid at time t, P is the price of gas purchased from the upper gas network at time t; g,buy (t) is the gas purchase volume from the upper gas grid during period t; Cost of curtailed energy for Where: WT P is the penalty cost for unit wind curtailment; WT,cut (t) is the wind power abandoned during period t; δ PV P is the penalty cost for unit abandonment; PV,cut (t) is the abandoned optical power in period t; By establishing various operating constraints as boundary conditions for solving the objective function, the proposed constraints include: 1) Renewable energy output constraints: Where: P WT (t) is the wind power output power in period t; is the upper limit of wind power output power; P PV (t) is the photovoltaic output power during period t; is the upper limit of photovoltaic output power; 2) Grid interaction power constraints: Where: P grid (t) is the power exchanged with the upper power grid at time t, is the maximum power interacting with the upper grid at time t; 3) Energy storage operation constraints: Since the models of electric, thermal, gas, and hydrogen energy storage devices are similar, the energy storage device constraints are modeled uniformly; Where: are the charging and discharging powers of the nth type of energy storage device during period t respectively; The maximum single charge and discharge power of the nth energy storage device; are binary variables, which are the charging and discharging state parameters of the nth energy storage device in period t, P ES,n (t) is the final output power of the nth energy storage device; are the charging and discharging efficiencies of the nth energy storage device; S n (t) is the real-time capacity of the nth energy storage device in period t; is the rated capacity of the nth type of energy storage device; are the upper and lower limits of the capacity of the nth type of energy storage device, respectively; 4) Constraints on purchasing power: Where: They are the gas and electricity purchase limits for each time period; 5) Electric power balance constraints: P e,buy (t)=P e,Load (t)+P e,EL (t)+P ES,e (t)-P WT (t)-P HFC,e (t) (16) Where: P ES,e (t) is the power input into the electric storage device during the period t; 6) Gas power balance constraints: P g,buy (t)=P g,Load (t)+P ES,g (t)+P g,CHP (t)+P g,GB (t)-P MR,g (t) (17) Where: P g,Load (t) is the gas load in the period t; P ES,g (t) is the power input into the electric storage device during the period t; 7) Thermal power balance constraints: P HFC,h (t)+P CHP,h (t)+P GB,h (t)=P h,Load (t)+P ES,h (t) (18) Where: P h,Load (t) is the heat load in the period t; P ES,h (t) is the power input into the heat storage device during the period t; 8) Hydrogen balance constraints: Where: is the power input to the hydrogen storage device during period t; 9) Carbon market constraints: Where: C CET,i and C CET,o are the total amount of carbon emission rights purchased and sold by IES to the external carbon market; and are the stock of carbon emission rights in the market and the upper limit of the shortfall; 10) Green Certificate Market Constraints: Where: C GCT,i and C GCT,o The numbers of green certificates purchased and sold by IES from the green certificate market; and are the stock of green certificates in the market and the upper limit of the shortage; B tra B is the number of green certificates converted into carbon quotas; GCT The number of green certificates traded in the market; The YALMIP toolbox and CPLEX solver are used on the MATLAB software platform to solve the optimal operation model of the integrated energy system.

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