Optimization design method for multi-energy-flow integrated energy system in low-carbon industrial park

Abstract

The invention belongs to the field of process energy integration in the chemical industry, and relates to an optimal design method for a multi-energy-flow comprehensive energy system in a low-carbon industrial park. According to the two-stage design method disclosed by the invention, configurations of energy consumption units with different time scales are respectively optimized by constructing MINLP and MILP models. In the first stage, from the park level, configuration of an inter-plant heat exchanger network, a waste heat recovery system and a public engineering system is optimized on the long-time scale; and in the second stage, on the premise of fixing the configuration in the first stage, the hydrogen electricity energy storage equipment is scheduled from a short time scale, and optimal parameters of a photovoltaic panel, an electrolytic bath, a hydrogen storage tank and a battery are optimized, so that the cold, hot and electrical requirements of the park are more effectively met. According to the method, a two-stage design method is provided according to the characteristics of the energy consumption unit under different time scales, and efficient distribution of multiple energy flows is achieved from long-time-scale equipment capacity configuration optimization to short-time-scale hydrogen-electricity dual-storage scheduling optimization.

Description

Technical Field

[0001] The present invention belongs to the field of process energy integration in the chemical industry, involving the conversion, storage, utilization and distribution of various energies in industrial parks. It mainly includes an inter-plant heat exchanger network, a waste heat recovery system, a utility system and a hydrogen supply system, and an optimization design method for a multi-energy flow integrated energy system in a low-carbon industrial park that integrates the four. Specifically, it is an optimization design method for a multi-energy flow integrated energy system in a low-carbon industrial park. Background Art

[0002] As a primary vehicle for industrial clustering and energy consumption, industrial parks face increasing complexity in energy management. Establishing integrated energy systems within industrial parks can convert incoming energy into different forms to meet the specific cooling, heating, electricity, and gas needs within the park. Inter-plant heat exchanger networks, waste heat recovery systems, and utility systems are common energy conversion and distribution technologies within integrated park energy systems. Coupling these three technologies for synergistic optimization can effectively improve the park's economic benefits and energy efficiency, thereby achieving efficient energy management.

[0003] In recent years, with the continued advancement of low-carbon development policies, the energy structure of industrial parks has undergone a significant transformation, and the integration of renewable energy into industrial parks has permeated every sector. Hydrogen, with its high calorific value, easy storage, and zero emissions, has become an effective vehicle for integrating most renewable energy sources. By building a hydrogen-based integrated energy system, waste heat from processes and electricity generated by renewable energy can be used to convert electricity into hydrogen. This excess electricity can be stored while meeting the hydrogen needs of industrial park processes, effectively reducing the carbon emissions and transportation costs of purchased "grey hydrogen."

[0004] literature( BJ, LF, PONCE-ORTEGA JM, et al. Multiobjective design of interplant trigeneration systems[J]. AIChE Journal, 2014, 60(1): 213-236.) proposed a trigeneration system consisting of a steam Rankine cycle, an organic Rankine cycle and an absorption refrigeration cycle, and optimized it synchronously with the in-plant heat exchanger network.

[0005] The literature (LIU L, SHENG Y, ZHUANG Y, et al. Multi-objective Optimization of Interplant Heat Exchanger Networks Considering Utility Steam Supply and Various Locations of Interplant Steam Generation / Utilization[J]. Industrial&Engineering Chemistry Research, 2020, 59(32): 14433-14446.) uses three grades of steam as the heat transfer medium to achieve the coordinated allocation of waste heat recovery and utility steam.

[0006] The literature (GU X, JI F, LIU L, et al. Global Energy Integration for IndustrialParks Incorporating Centralized Trigeneration and Interplant HEN[J]. Industrial&Engineering Chemistry Research, 2023, 62(43): 17805-17823.) established a superstructure-based MINLP model to achieve the generation, conversion, distribution and reuse of energy in industrial parks by coupling inter-plant waste heat recovery and multi-energy cogeneration.

[0007] The literature (HUO Q, LIU Q, DENG H, et al. Research on dual-layer optimization strategy of photovoltaic-storage-hydrogen system in coal chemical industry park [J]. Renewable Energy, 2024, 230: 120813.) used renewable energy to produce hydrogen to transform the coal chemical park, established a photovoltaic-storage-hydrogen system, and improved the park's ability to absorb renewable energy through dual hydrogen and electricity storage.

[0008] However, the current hydrogen-based integrated energy system relies too much on external energy input to meet the cooling, heating, electricity and gas needs of industrial parks, and fails to fully recover and utilize process waste heat; secondly, the system usually optimizes capacity configuration under the premise of a fixed equipment structure, and does not consider the overall optimization of the system structure at the park level; finally, research on the multi-time scale integrated optimization of hydrogen supply systems and integrated energy systems is still not in-depth enough. Summary of the Invention

[0009] In order to solve the above problems, the present invention proposes a two-stage method to design a hydrogen-based integrated energy system for an industrial park, using hydrogen energy as a renewable energy carrier to participate in the energy conversion, storage, utilization and distribution process within the park, and to meet the park's various energy needs such as cooling, heating, and electricity through the coordination of multiple energy flows. The present invention first uses steam of different grades to carry out inter-plant heat integration, and at the same time uses three waste heat recovery technologies, namely organic Rankine cycle (ORC), absorption refrigeration cycle (ARC), and electric compression refrigeration cycle (ECR), and natural gas boilers to perform trigeneration of cooling, heating, and electricity, and optimizes the centralized or distributed configuration of the waste heat recovery system at the park level. On this basis, photovoltaic power generation units are integrated, and the electricity they generate is incorporated into the park microgrid. The surplus electricity is converted into hydrogen energy through a water electrolysis device for industrial production or natural gas hydrogen-blended combustion.

[0010] The two-stage design approach proposed in this paper optimizes the configuration of energy-consuming units at different timescales by constructing MINLP and MILP models. In the first stage, starting from the park level, the configuration of the inter-plant heat exchanger network, waste heat recovery system, and utility system is optimized on a long-term scale. In the second stage, while maintaining the configuration of the first stage, the hydrogen-electric energy storage equipment is dispatched on a short-term scale, optimizing the optimal parameters of photovoltaic panels, electrolyzers, hydrogen storage tanks, and batteries to more effectively meet the park's heating, cooling, and electrical needs.

[0011] The present invention is achieved through the following technical solutions:

[0012] The optimization design method of the multi-energy flow integrated energy system of the low-carbon industrial park includes the following steps:

[0013] Phase 1:

[0014] To facilitate model description, the subscripts p, rr, i, j, k, n, and o are used to denote plant (p), plant (rr), hot stream (i), cold stream (j), stage number (k), steam grade (n), and ORC working fluid type (o), respectively. The model also defines the following sets: P represents the plant set, HPS represents the hot stream set, CPS represents the cold stream set, ST represents the stage set, NSP represents the steam grade set, and OR represents the ORC working fluid type set, with p and rr ∈ P, i ∈ HPS, j ∈ CPS, k ∈ ST, n ∈ NSP, and o ∈ OR.

[0015] (1) Construct an inter-plant heat exchanger network model: Use high, medium, and low pressure steam as intermediate media for inter-plant heat exchange. The steam generated by high-grade waste heat sources can be incorporated into the park steam network and exchange heat with the steam generated by the public engineering system. By constructing a hierarchical superstructure, the inter-plant heat exchanger network structure is optimized.

[0016] The model of the inter-plant heat exchanger network includes energy balance, mass balance, temperature constraints, and logical constraints on the existence of heat exchangers. The specific mathematical description is as follows:

[0017] The energy balance of waste heat source in the inter-plant heat exchanger network is shown in equations (1)-(2), fh p,i represents the heat capacity flow rate of the residual heat flow, Represents the inlet and outlet temperatures. The steam is generated by heat exchange with condensate of different grades of steam, and is integrated with the steam generated by the utility system for indirect heat integration between plants. Low-grade waste heat can be used to drive ORC to generate electricity. and ARC Refrigeration The remaining unused waste heat can be used through the cold utility project Low-temperature cooling water generated by ARC and ECR-generated low-temperature frozen brine Allow to cool. Represents the total amount of steam generated by waste heat.

[0018] The energy distribution balance constraint of the heat sink (steam heat demand) is given by equations (3)-(8). Representing heat sinks from different plants, Represents high, medium and low pressure steam that can be used to heat low-level heat sinks. Represents high and medium pressure steam that can be used to heat intermediate heat sinks. Represents high-pressure steam that can be used to heat advanced heat sinks. Represents the sum of steam requirements for heating heat sinks of different levels.

[0019]

[0020] The energy balance and mass balance of the branch stream in each level of superstructure are shown in Equations (9)-(18), fh1 p,i,k,n and fh2 p,i,k Represents the flow rate of different branch streams, fh1 p,i,k,n Heat exchange with steam condensate to generate steam, fh2 p,i,k Does not participate in heat exchange; p,i,k represents the temperature at the series position k in the superstructure, th1 p,i,k,n Represents the outlet temperature of the branch stream. p,i,o represents the flow rate of the branch stream and the heat exchange with different ORC systems, tho p,i Represents the temperature of the stream after heat exchange with the ORC generator, th2 p,i Represents the temperature after heat exchange between the stream and the ARC generator, th3 p,i Represents the temperature after heat exchange between the stream and the cold utility, th4 p,i Represents the temperature of the stream after heat exchange with the ARC evaporator.

[0021]

[0022] Formulas (20)-(29) are temperature constraints and logic constraints at different locations. Formulas (20)-(23) can ensure that the temperature decreases step by step according to the direction. p,i,k,n Indicates whether the process hot stream is matched with the steam generator for heat exchange: 1 means yes, 0 means no. They represent whether the process hot stream has heat exchange matching with the ORC generator, ARC generator, cold utility, low-temperature cooling water of ARC evaporator, and low-temperature frozen brine of ECR.

[0023]

[0024] th p,i,k-1 ≥th p,i,k (k≠1),p∈P,i∈HPS,k∈ST (21)th1 p,i,k,n ≥th1 p,i,k+1,n (k≠ST),p∈P,i∈HPS,k∈ST,n∈NSP (22)

[0025]

[0026] zh1 p,i,k,n ×δ≥fh1 p,i,k,n ,p∈P,i∈HPS,k∈ST,n∈NSP (24)

[0027]

[0028] The heat transfer area of ​​each process hot stream in the heat exchanger is given by formulas (30)-(33). tht1 and tht2 represent the inlet and outlet temperatures of the matching hot stream, tct1 and tct2 represent the inlet and outlet temperatures of the matching cold stream, and Δt1 and Δt2 represent the heat transfer temperature difference at both ends of the heat exchanger. The model gives the minimum allowable heat transfer temperature difference (Δt min ), h represents the heat transfer coefficient. A binary variable z is introduced to indicate whether a matching relationship exists. δ is a maximum value, and Area represents the heat transfer area. The heat transfer area calculation formula for ORC, ARC, ECR, and heating and cooling utilities is the same.

[0029] Δt min ≤Δt1≤tht1-tct1+δ×(1-z) (30)Δt min ≤Δt2≤tht2-tct2+δ×(1-z)(31)

[0030]

[0031] q=Area×h×Δt (33)

[0032] (2) Constructing a waste heat recovery system model: The waste heat recovery system consists of an organic Rankine cycle, an absorption refrigeration cycle, and an electric compression refrigeration cycle. The ORC system converts heat energy into electrical energy by recovering low-grade waste heat, and provides two working media (R245fa and n-Hexane) to cope with different waste heat recovery scenarios. The ARC system converts low-grade waste heat into low-temperature cooling water, which can be used to cool process hot streams or meet the cooling needs of park offices. The ECR system is driven by electricity distributed by the park microgrid and can produce low-temperature frozen brine to meet the cooling needs of process hot streams at lower temperatures. In addition, the ORC, ARC, and ECR systems are considered to be centralized or distributed respectively. The centralized layout can save equipment costs, but will result in higher pipeline transportation costs. The distributed layout can save pipeline transportation costs, but will result in higher equipment costs. The optimal waste heat recovery system configuration can be obtained through optimization.

[0033] The ORC system consists of a generator, a condenser, a pump, and a turbine. cen and dis represent centralized and distributed arrangements, respectively. Since the energy balance relationship is the same in both cases and only the calculation method of the generator energy is different, only the energy balance relationship of the internal cycle of the distributed ORC system is given here. The specific mathematical description is shown in Equations (34)-(39). Represent the heat recovered by distributed and centralized ORC generators, Represent the low-pressure steam used to drive the distributed and centralized ORCs, respectively. Represents the total amount of low-pressure steam used to drive the ORC. Indicates the waste heat recovered by ORC in a single plant, On behalf of ORC, waste heat is recovered from the entire park. represents the electrical energy generated by ORC, represents the pump work required by ORC, Indicates the heat generated by the ORC condenser. represents the efficiency factor of the ORC system, Represents the efficiency coefficient of the pump in the ORC cycle. Binary variable Used to determine whether a single plant has one of the two preset ORC working fluid configurations, binary variable zh orc,dis Used to determine whether ORC adopts distributed layout, binary variable zh orc,cen Used to determine whether ORC adopts centralized layout.

[0034]

[0035] The ARC system consists of a generator, evaporator, condenser, absorber, and pump. To improve the sharing and utilization efficiency of waste heat resources, a cold sharing mechanism is established for distributed ARC. Some of the cold energy generated by waste heat-rich plants is transported via pipelines to plants with insufficient cold energy. Similar to the ORC system, only the energy balance relationship within the distributed ARC system is presented here. The specific mathematical description is shown in Equations (41)-(50). q arc_generator,cen Represent the heat recovered by distributed and centralized ARC generators, Represents the low-pressure steam used to drive the distributed and centralized ARCs, Represents the total amount of low pressure steam used to drive the ARC. Indicates the waste heat recovered by ARC in a single plant, Represents ARC to recover waste heat from the entire park. COP arc is the efficiency factor of the ARC system, represents the efficiency coefficient of the absorber inside the ARC system, Represents the efficiency coefficient of the pump inside the ARC system, a binary variable Used to determine whether a single factory has ARC configuration, binary variable zh arc,dis Used to determine whether ARC adopts distributed layout, binary variable zh arc,cen Used to determine whether ARC adopts centralized layout. Represents the energy absorbed by the ARC evaporator, represents the energy generated by the ARC absorber, represents the pumping work required by the ARC, Represents the energy generated by the condenser. Indicates the cooling demand of factory offices. Refers to the cold energy transported by factory p to other factories, Refers to the cold energy supplied to factory p by other factories. A factory is not allowed to receive and transport cold energy at the same time.

[0036]

[0037]

[0038] The ECR system consists of a compressor, an evaporator, a condenser, and a throttle valve. Similar to the ORC system, only the energy balance relationship of the internal cycle of the distributed ECR system is given here. The specific mathematical description is shown in Equations (51)-(56). q ecr _eva,cen Represent the heat absorbed by the distributed and centralized ECR evaporators, Represents the work done by the ECR compressor, Represents the electrical energy consumed by the ECR compressor, Represents the heat released by the ECR condenser. is the efficiency factor of the ECR system, is the efficiency coefficient of the ECR internal evaporator, a binary variable Used to determine whether a single factory has an ECR system configuration, binary variable zh ecr,dis Used to determine whether ECR adopts distributed layout, binary variable zh ecr,cen Used to determine whether ECR adopts centralized layout.

[0039]

[0040] (3) Constructing a utility system model: The park purchases natural gas from outside, converts it into ultra-high-pressure steam using gas boilers, and extracts it through turbines to generate three levels of steam and electricity. The steam generated is used together with the steam generated by the waste heat steam generator for inter-plant heat exchange. The low-pressure steam can also be used to drive ORC power generation or ARC cooling; the electric boiler is used as a way to compensate for the low-pressure steam. The generated electricity, the electricity converted by the ORC, and the electricity purchased from the external power grid are all integrated into the park microgrid to meet the electricity needs of the office, electric boiler, and ECR system. Excess electricity can be sold to the outside world.

[0041] The energy balance of gas boiler, electric boiler and microgrid is as shown in equations (57)-(63). represents the steam extracted by the turbine, Represents the steam generated by the waste heat steam generator, represents a heat sink, Indicates the quality of steam generated by gas boiler, r n Indicates the enthalpy of steam. wt total represents the electrical energy generated by the turbine, It represents the specific enthalpy of different grades of saturated steam entering and leaving the turbine, represents turbine efficiency, heatcap represents the calorific value of natural gas combustion, boilerpreheat n It represents the heat required to generate superheated steam in the boiler, and ahour represents the working hours in a year. represents the efficiency of the boiler, q fuel represents the amount of natural gas used, and Dt represents the time factor. Represents the low-pressure steam generated by the electric boiler, ele eb Indicates the electric energy consumed by the electric boiler. Represents the efficiency of the electric boiler, the binary variable z eb Used to determine whether there is an electric boiler. buy 、ele sale Indicates the electric energy purchased or sold from the external power grid. represents the electric energy generated by the centralized ORC, ele ecr,cen Indicates the power consumed by the centralized ECR.

[0042]

[0043] (4) Objective function: In order to obtain the best multi-energy flow configuration of the park in the first stage, the optimization is carried out with the minimum total annual cost (TAC) as the goal. The objective function is shown in Equation (64). It mainly includes the inter-plant heat exchanger network cost COST HEN , Waste heat recovery system cost COST WHRC and utility costs COST UTILITY .

[0044] TAC=COST HEN +COST WHRC +COST UTILITY (64)

[0045] The inter-plant heat exchanger network cost is given by formula (65), which is mainly composed of fixed cost FIC and area cost AC, where area represents the area of ​​the heat exchanger and α represents the factor for calculating the area cost.

[0046] COST HEN =FIC+AC×area α (65)

[0047] The mathematical expression of the waste heat recovery system cost is shown in formulas (66)-(74), COST EQrepresents the cost of equipment, COST TRANS represents the cost of equipment, COST pump represents the cost of equipment, COST tur-orc represents the cost of equipment, COST comp represents the cost of equipment, COST pipe represents the cost of equipment, COST pump represents the cost of equipment, COST p,i represents the cost of equipment, COST pump represents the cost of equipment, COST pump represents the cost of equipment, COST pump represents the cost of equipment, COST pump represents the cost of equipment, COST tur-orc represents the cost of equipment, COST tur-orc represents the cost of equipment, COST comp represents the cost of equipment, COST comp represents the cost of equipment, COST pipe1 represents the cost of equipment, COST pipe2 represents the cost of equipment, COST pipe3 represents the cost of equipment, COST pump1 represents the cost of equipment, COST pump2 represents the cost of equipment, COST pump3 represents the cost of equipment, COST is used to determine if there is a pipeline transportation for the plant.

[0048] represents the cost of equipment, COST WHRC represents the cost of equipment, COST EQ represents the cost of equipment, COST TRANS (66)

[0049]

[0050]

[0051] represents the cost of equipment, COST GB represents the cost of equipment, COST EBrepresents the cost of the electric boiler, COST CU represents the cost of the cold utility, COST ELE represents the cost of the electricity. COST fuel represents the cost of the fuel. COST turbine represents the cost of the turbine, COST boiler represents the cost of the boiler, ratio n represents the ratio factor of the steam quality, price fuel represents the cost of the fuel price. CPCOST turbine represents the fixed cost of the turbine, OPCOST turbine represents the cost factor of the operation of the turbine; CPCOST boiler represents the fixed cost of the gas boiler, OPCOST boiler represents the cost factor of the operation of the gas boiler. COST ebcap represents the equipment cost of the electric boiler, COST ebom represents the running cost of the electric boiler, rate represents the exchange rate, CPCOST eb represents the equipment cost factor of the electric boiler, OPCOST eb represents the cost factor of the operation of the electric boiler. qc represents the total consumption of the cold utility, price cu represents the price of the cold utility, price buy-ele , price sale-ele buy and sell electricity prices.

[0052] COST UTILITY = COST GB + COST EB + COST CU + COST ELE (75)

[0053] COST GB = COST fuel + COST turbine + COST boiler (76)

[0054] COST turbine = CPCOST turbine + OPCOST turbine x wt total (77)

[0055]

[0056] COST fuel = q fuel x price fuel (79)

[0057] COST EB =COST ebcap +COST ebom (80)

[0058]

[0059] COST ebom =OPCOST eb ×ele eb ×rate×ahour (82)

[0060] COST CU =qc×price cu (83)

[0061]

[0062] Phase 2:

[0063] In the second stage, the hydrogen supply system is optimized. After solving the first-stage model, the optimal configuration of the inter-plant heat exchanger network, waste heat recovery system, and utility system can be obtained. The relevant configuration parameters optimized in the first stage are fixed, and the hydrogen supply system is optimized from a shorter time scale. Compared with the first-stage model, the second-stage model adds relevant mathematical constraints for photovoltaic power generation, water electrolysis hydrogen production, hydrogen storage, and electricity storage. The constraint equations for the inter-plant heat exchanger network, waste heat recovery system, and utility system are the same as those in the first stage. Only the time index is added, so they will not be repeated. In the model, the subscript m∈M represents 24 hours in a day.

[0064] (1) Constructing a photovoltaic power generation model: The relevant equipment parameters of the solar panels are given. The electricity generated by the solar panels is integrated with the electricity generated by the ORC system and the turbine into the park microgrid to meet the various power needs of the park. The related energy balance constraints are shown in Equations (86)-(89). represents the electrical energy generated by the photovoltaic panel at time m, IC PV Indicates the number of photovoltaic panels, A PV Represents the area of ​​each photovoltaic panel, represents the efficiency of the photovoltaic panel at time m, G m represents the radiation intensity at time m, η inverter represents the efficiency of the photovoltaic inverter, Indicates the efficiency of photovoltaic panels under standard conditions, β PV represents the temperature coefficient, Indicates the temperature of the photovoltaic panel, T ref Indicates the temperature of photovoltaic panels under standard working conditions. Indicates the ambient temperature of the photovoltaic panel, Tnoct Indicates the temperature of the photovoltaic panel under normal working conditions, G ref Indicates the radiation intensity of photovoltaic panels under standard conditions, EPV max Indicates the maximum output power of the photovoltaic system.

[0065]

[0066]

[0067] (2) Constructing a battery model: The power balance relationship of the park and the battery charge and discharge constraints are shown in formulas (90)-(95). represents the electrical energy generated by the ORC system at time m, represents the electrical energy generated by the steam extracted by the turbine at time m, represents the electric energy purchased from the external power grid at time m, represents the electrical energy released by the battery at time m, represents the electrical energy generated by the photovoltaic panels at time m, represents the energy stored in the battery at time m, represents the electric energy consumed by the electric boiler at time m, represents the power consumed by the ECR system at time m, represents the office electricity demand of the park at time m, Indicates the electric energy consumed by the electrolytic cell at time m. es m represents the energy storage capacity of the battery at time m, η ch ,η dis Representing the charging and discharging efficiency, using binary variables To judge the state of charge and discharge, only one of them can exist. ch,max 、ele dis,max Indicates the maximum power of charging and discharging.

[0068]

[0069] (3) Constructing an electrolyzer model: The park microgrid prioritizes meeting the power needs of the ECR system, electric boiler, and office. The remaining electricity is converted into hydrogen through the electrolyzer device. The energy and mass balance equations are shown in Equations (96)-(97). represents the electrical energy converted by the electrolytic cell at time m, η p_h2 Indicates the working efficiency of the electrolytic cell, represents the amount of hydrogen converted at time m, H h2 Indicates the calorific value of hydrogen.

[0070]

[0071]

[0072] (4) Constructing a hydrogen storage tank model: The hydrogen produced by the electrolyzer can be used to meet the hydrogen demand of process production. On the other hand, it can be mixed with natural gas for combustion, and the remaining hydrogen is stored in the hydrogen storage tank. Since the second stage considers the combustion of natural gas mixed with hydrogen based on the first stage, the energy balance relationship of the gas boiler needs to be changed to formula (104), and the hydrogen mixing ratio needs to be constrained to be less than or equal to 0.2.

[0073] The mathematical model of the entire hydrogen storage part is shown in formulas (98)-(106). Indicates the amount of hydrogen released and stored in the hydrogen storage tank at time m, represents the process hydrogen demand at time m, Indicates the amount of hydrogen used to mix with natural gas at time m. HST m Represents the capacity of the hydrogen storage tank at time m, a binary variable They are used to judge the status of releasing and storing hydrogen respectively. represents the mass of natural gas consumed by the boiler at time m, represents the volume flow rate of natural gas at time m, ω m Indicates the hydrogen blending ratio of natural gas at time m.

[0074]

[0075] 0≤ω m ≤0.2,m∈M (106)

[0076] (5) Objective function: In order to obtain the optimal parameters of photovoltaic panels, electrolyzers, hydrogen storage tanks and batteries, and to achieve the scheduling results of hydrogen and electricity dual storage, the objective function of the second stage only includes photovoltaic panels (COST PV ), electrolytic cell (COST PH2 ), hydrogen storage tank (COST HST )、Batteries(COST BAT ) and other equipment costs, as well as fuel (COST FUEL ), Cold Utilities (COST CU ), purchased electricity (COST ELE ) operating costs, and in order to achieve low-carbon operation of the entire system, carbon emissions are converted into carbon taxes (COST ACE ) is added to the objective function. The specific mathematical expression is shown in formula (107).

[0077]

[0078] The calculation formulas for carbon emissions and carbon tax are shown in (108)-(109). The sources of carbon emissions are mainly composed of carbon dioxide generated by fuel combustion and purchased electricity. ACE represents the total carbon emissions, GE represents the total carbon emissions, and ngCarbon emission factor of fuel combustion, GE ele Carbon emission factor of purchased electricity, days represents working days, and cct represents carbon price, Natural gas consumption at m time.

[0079]

[0080] The calculation formula of equipment cost of photovoltaic panels, electrolytic cells, hydrogen storage tanks, batteries and the like is shown as (110)-(113), CPCOST PV , OPCOST PV CPCOST PH2 , OPCOST PH2 CPCOST ph2max CPCOST HST CPCOST max CPCOST BAT CPCOST max CPCOST

[0081]

[0082] CPCOST HST CPCOST max CPCOST HST CPCOST

[0083] CPCOST BAT CPCOST max CPCOST BAT CPCOST

[0084] In summary, the optimal configuration of each energy-using unit in the park can be obtained by the two-stage design method, so that the cascade utilization of energy and high proportion of renewable energy consumption can be realized.

[0085] Compared with the prior art, the present application has the following beneficial effects:

[0086] (1) Compared with the traditional integrated energy system, the present application pays more attention to the waste heat recovery and utilization in the industrial park and renewable energy consumption, so as to meet the cold, heat, electricity and gas demand of the industrial park and reduce the dependence on external primary energy.

[0087] (2) The model structure is rich, various energy conversion units are considered, and the centralized or distributed layout of the energy using unit is optimized according to the characteristics of the energy demand and waste heat resources of different factory areas, so that the waste heat resources between different factories are shared, and the energy utilization efficiency is effectively improved.

[0088] (3) The present application proposes a two-stage design method according to the characteristics of the energy using unit under different time scales, from the long-time scale device capacity configuration optimization to the short-time scale hydrogen and electricity dual storage scheduling optimization, and realizes efficient distribution of multi-energy flow. BRIEF DESCRIPTION OF DRAWINGS

[0089] Figure 1 It is an integrated structure of a multi-energy flow comprehensive energy system.

[0090] Figure 2 It is a schematic diagram of the low-carbon industrial park multi-energy flow comprehensive energy system optimization design method.

[0091] Figure 3 It is a cold and electricity demand and radiation intensity data diagram of an industrial park.

[0092] Figure 4 It is the optimal inter-plant heat exchanger network, waste heat recovery system and utility system configuration after the first stage optimization of the embodiment.

[0093] Figure 5 It is a hydrogen storage tank scheduling schematic diagram under different times in the second stage of the embodiment.

[0094] Figure 6 It is an electricity balance schematic diagram under different times in the second stage of the embodiment.

[0095] Figure 7 It is a waste heat utilization schematic diagram under different times in the second stage of the embodiment.

[0096] Figure 8 It is a steam balance schematic diagram under different times in the second stage of the embodiment. DETAILED DESCRIPTION

[0097] The specific implementation mode of the present application will be further illustrated below in combination with the above steps, technical solutions, the structure shown in Figure 1 and the flow shown in Figure 2 , taking a chemical park containing six factories as the research object.

[0098] The process heat flow and steam demand data of the park are shown in Table 1, the cold and electricity demand and radiation data are shown in Figure 3 , and the annual hydrogen process demand of the whole park is 6640000m 3. The temperatures of low-pressure, medium-pressure and high-pressure steam (LPS / MPS / HPS) are 170.4℃, 198.3℃ and 263.9℃ respectively, and the pressures of low-pressure, medium-pressure and high-pressure steam are 0.8MPa, 1.5MPa and 5.0MPa respectively. The inlet and outlet temperatures of cooling water are 20℃ and 30℃. The price of natural gas is 0.227$ / kg, the price of cold utility is 10$ / kW / yr, the minimum heat transfer temperature difference between the waste heat stream and the steam generator and cooling water is 10℃, and the minimum heat transfer temperature difference between the waste heat stream and the ARC evaporator and ECR evaporator is 5℃; in distributed waste heat recovery, the minimum heat transfer temperature difference between the ARC generator and ORC generator and the waste heat stream in the plant is 10℃; in centralized waste heat recovery, the minimum heat transfer temperature difference between the ARC generator and ORC generator and the waste heat stream in the plant is 20℃. The heat transfer coefficient with phase change is 1kW / m 2 / K, the heat transfer coefficient without phase change is 0.5kW / m 2 / K. The equipment has a service life of 5 years and a capital rate of 12%. The area of ​​each photovoltaic panel is 1.6m 2 The efficiency of the photovoltaic inverter is 0.9, the efficiency of the photovoltaic panel under standard conditions is 0.18, and its temperature coefficient is 0.005. The temperature and radiation intensity under standard working conditions of the photovoltaic panel are 25℃ and 800W / m 2 The working efficiency of the electrolyzer is 0.95, and the calorific value of hydrogen is 12750kJ / m 3 .

[0099] Table 1 Stream data of the embodiment

[0100]

[0101]

[0102] Through the first stage optimization solution, the optimal configuration of the inter-plant heat exchanger network, waste heat recovery system and utility system can be obtained. The specific structure is as follows: Figure 4 As shown. For the waste heat recovery system, ORC chose a centralized configuration, using n-Hexane as the working medium. ARC chose a distributed configuration, deployed in Plants 1, 2, and 5. Excess cooling energy generated within the plants was piped to Plants 3, 4, and 6 through cooling sharing. ECR chose centralized cooling using electricity distributed by the campus microgrid, which was then piped to Plants 1 and 6. In the inter-plant heat exchanger network, Plants 2 and 5 generated 7,974 kW of LPS, which, along with the 356 kW of LPS, 813 kW of MPS, and 1,431 kW of HPS generated by the gas-fired boilers, met the steam heat needs of the other plants.

[0103] Through the second stage solution, the maximum capacity configuration of PV, BAT, EL and HST, as well as the scheduling of hydrogen energy, electricity, waste heat and steam within 24 hours a day can be obtained. Figure 5 It can be found that, affected by solar radiation, the hydrogen production rate and hydrogen storage rate are roughly the same, and basically occur in the range of 8-18 hours. The excess electricity in the system will be converted into hydrogen and stored first, but due to the maximum capacity configuration of the electrolyzer, when the excess electricity in a certain hour exceeds the maximum power of the electrolyzer, this part of the electricity will be stored in the battery and will be released in time according to the electricity situation in the system. The specific battery charging and discharging conditions are as follows: Figure 6 In addition, when the load in the system fluctuates, the waste heat resources will be adjusted accordingly to cope with the fluctuation. Figure 7 It can be seen that during the hours of 8-19 hours, the cooling demand of the park is high, and the waste heat in the system will flow more to ARC for cooling. When the cooling demand of the park decreases during the hours of 1-7 hours and 20-24 hours, the waste heat in the system will flow more to ORC for power generation to obtain electricity benefits. Figure 8 It can be seen that at 11, 14, 15, 16, and 17 hours, since the waste heat of the park cannot meet the cooling needs of ARC, the gas boiler will generate an additional 153kW, 260kW, 48kW, 35kW, and 285kW of low-pressure steam to drive ARC.

Claims

1. The optimization design method of multi-energy flow integrated energy system in low-carbon industrial park is characterized by: The process includes the following steps: Phase 1: Subscripts p, rr, i, j, k, n, and o are used to represent plant p, plant rr, hot stream i, cold stream j, stage k, steam level n, and type o of ORC working fluid, respectively; corresponding sets are defined: P represents the plant set, HPS represents the hot stream set, CPS represents the cold stream set, ST represents the stage set, NSP represents the steam level set, and OR represents the type set of ORC working fluid, with p and rr∈P, i∈HPS, j∈CPS, k∈ST, n∈NSP, and o∈OR; (1) Construct an inter-plant heat exchanger network model: Use high, medium, and low pressure steam as the intermediate medium for inter-plant heat exchange. The steam generated by high-grade waste heat sources can be incorporated into the park steam network and exchange heat with the steam generated by the utility system. By constructing a hierarchical superstructure, the inter-plant heat exchanger network structure is optimized. The model of the inter-plant heat exchanger network includes energy balance, mass balance, temperature constraints, and logical constraints on the existence of heat exchangers. The specific mathematical description is as follows: The energy balance of waste heat source in the inter-plant heat exchanger network is shown in equations (1)-(2), fh p,i represents the heat capacity flow rate of the residual heat flow, Represents the inlet and outlet temperatures; high-grade waste heat Steam is generated by heat exchange with condensate of different grades of steam, and is integrated with steam generated by the utility system for indirect inter-plant heat integration; low-grade waste heat is used to drive ORC to generate electricity and ARC Refrigeration The remaining unused waste heat is used by the cold utility project Low-temperature cooling water generated by ARC and ECR-generated low-temperature frozen brine Cooling Represents the total amount of steam generated by waste heat; The energy distribution balance constraint of the heat sink is given by equations (3)-(8); Representing heat sinks from different plants, Represents the high, medium and low pressure steam used to heat the low-level heat sink, Represents the high and medium pressure steam used to heat the intermediate heat sink, Represents the high-pressure steam used to heat the advanced heat sink, It represents the sum of steam requirements for heating heat sinks of different levels; The energy balance and mass balance of the branch stream in each level of superstructure are shown in Equations (9)-(18), fh1 p,i,k,n and fh2 p,i,k Represents the flow rate of different branch streams, fh1 p,i,k,n Heat exchange with steam condensate to generate steam, fh2 p,i,k Does not participate in heat exchange; p,i,k represents the temperature at the series position k in the superstructure, th1 p,i,k,n represents the outlet temperature of the branch stream; fho p,i,o represents the flow rate of the branch stream and the heat exchange with different ORC systems, tho p,i Represents the temperature of the stream after heat exchange with the ORC generator, th2 p,i Represents the temperature after heat exchange between the stream and the ARC generator, th3 p,i Represents the temperature after heat exchange between the stream and the cold utility, th4 p,i represents the temperature of the stream after heat exchange with the ARC evaporator; Formulas (20)-(29) are temperature constraints and logic constraints at different locations; Formulas (20)-(23) can ensure that the temperature decreases step by step according to the direction; the binary variable zh1 p,i,k,n Indicates whether the process hot stream is matched with the steam generator for heat exchange: 1 means yes, 0 means no; They represent whether the process hot stream has heat exchange matching with the ORC generator, ARC generator, cold utility, low-temperature cooling water of ARC evaporator, and low-temperature refrigerated brine of ECR; th p,i,k-1 ≥th p,i,k (k≠1),p∈P,i∈HPS,k∈ST (21) th1 p,i,k,n ≥th1 p,i,k+1,n (k≠ST),p∈P,i∈HPS,k∈ST,n∈NSP (22) zh1 p,i,k,n ×δ≥fh1 p,i,k,n ,p∈P,i∈HPS,k∈ST,n∈NSP (24) The heat transfer area of ​​each process hot stream in the heat exchanger is given by formulas (30)-(33); tht1 and tht2 represent the inlet and outlet temperatures of the matching hot stream, tct1 and tct2 represent the inlet and outlet temperatures of the matching cold stream, and Δt1 and Δt2 represent the heat transfer temperature difference at both ends of the heat exchanger. The model gives the minimum allowable heat transfer temperature difference Δt min , h represents the heat transfer coefficient; A binary variable z is introduced to indicate whether a matching relationship exists, δ is a maximum value, and Area represents the heat exchange area. The heat exchange area calculation method for ORC, ARC, ECR, and hot and cold utility projects is the same. Δt min ≤Δt1≤tht1-tct1+δ×(1-z) (30) Δt min ≤Δt2≤tht2-tct2+δ×(1-z) (31) q=Area×h×Δt (33) (2) Constructing a waste heat recovery system model: The waste heat recovery system consists of an organic Rankine cycle (ORC), an absorption refrigeration cycle (ARC), and an electric compression refrigeration cycle (ECR); The ORC system consists of a generator, a condenser, a pump, and a turbine. cen and dis represent centralized and distributed arrangements, respectively. The energy balance relationship of the internal cycle of the distributed ORC system is mathematically described as shown in Equations (34)-(39); Represent the heat recovered by distributed and centralized ORC generators, Represent the low-pressure steam used to drive the distributed and centralized ORCs, respectively. represents the total amount of low-pressure steam used to drive the ORC; Indicates the waste heat recovered by ORC in a single plant, Recover waste heat from the entire park on behalf of ORC; represents the electrical energy generated by ORC, represents the pump work required by ORC, Indicates the heat generated by the ORC condenser; represents the efficiency factor of the ORC system, Represents the efficiency coefficient of the pump in the ORC cycle; binary variable Used to determine whether a single plant has one of the two preset ORC working fluid configurations, binary variable zh orc,dis Used to determine whether ORC adopts distributed layout, binary variable zh orc,cen Used to determine whether ORC adopts centralized layout; The energy balance relationship of the internal cycle of the distributed ARC system is described mathematically as shown in Equations (41)-(50); q arc_generator,cen Represent the heat recovered by distributed and centralized ARC generators, Represents the low-pressure steam used to drive the distributed and centralized ARCs, represents the total amount of low-pressure steam used to drive the ARC; Indicates the waste heat recovered by ARC in a single plant, Represents ARC to recover waste heat from the entire park; COP arc is the efficiency factor of the ARC system, represents the efficiency coefficient of the absorber inside the ARC system, Represents the efficiency coefficient of the pump inside the ARC system, a binary variable Used to determine whether a single factory has ARC configuration, binary variable zh arc,dis Used to determine whether ARC adopts distributed layout, binary variable zh arc,cen Used to determine whether ARC adopts centralized layout; Represents the energy absorbed by the ARC evaporator, represents the energy generated by the ARC absorber, represents the pumping work required by the ARC, represents the energy generated by the condenser; Indicates the cooling demand of factory offices. Refers to the cold energy transported by factory p to other factories, Refers to the cold energy delivered to factory p by other factories. A factory is not allowed to receive and deliver cold energy at the same time. The energy balance relationship of the internal cycle of the distributed ECR system is described mathematically as shown in Equations (51)-(56); q ecr_eva,cen Represent the heat absorbed by the distributed and centralized ECR evaporators, Represents the work done by the ECR compressor, Represents the electrical energy consumed by the ECR compressor. Represents the heat released by the ECR condenser; is the efficiency factor of the ECR system, is the efficiency coefficient of the ECR internal evaporator, a binary variable Used to determine whether a single factory has an ECR system configuration, binary variable zh ecr,dis Used to determine whether ECR adopts distributed layout, binary variable zh ecr,cen Used to determine whether ECR adopts centralized layout; (3) Constructing a utility system model: The park purchases natural gas from outside, converts it into ultra-high-pressure steam using gas boilers, and extracts it through turbines to generate three levels of steam and electricity. The steam generated is used together with the steam generated by the waste heat steam generator for inter-plant heat exchange. The low-pressure steam can also be used to drive ORC power generation or ARC refrigeration; the electric boiler is a way to compensate for the low-pressure steam; the generated electricity, the electricity converted by ORC, and the electricity purchased from the external power grid are all integrated into the park microgrid to meet the electricity needs of the office, electric boiler, and ECR system. The excess electricity can be sold to the outside world; The energy balance of gas boiler, electric boiler and microgrid is as shown in equations (57)-(63). represents the steam extracted by the turbine, Represents the steam generated by the waste heat steam generator, represents a heat sink, Indicates the quality of steam generated by gas boiler, r n Indicates the enthalpy of steam; wt total represents the electrical energy generated by the turbine, It represents the specific enthalpy of different grades of saturated steam entering and leaving the turbine, represents turbine efficiency, heatcap represents the calorific value of natural gas combustion, boilerpreheat n It represents the heat required to generate superheated steam in the boiler, and ahour represents the working hours in a year. represents the efficiency of the boiler, q fuel represents the amount of natural gas used, and Dt represents the time factor; Represents the low-pressure steam generated by the electric boiler, ele eb Indicates the electric energy consumed by the electric boiler. Represents the efficiency of the electric boiler, the binary variable z eb Used to determine whether there is an electric boiler;ele buy 、ele sale Indicates the electric energy purchased or sold from the external power grid. represents the electric energy generated by the centralized ORC, ele ecr,cen It represents the electric energy consumed by the centralized ECR; (4) Objective function: In order to obtain the optimal multi-energy flow configuration of the park in the first stage, the optimization is carried out with the minimum annual total cost TAC as the goal. The objective function is shown in Equation (64); it mainly includes the inter-plant heat exchanger network cost COST HEN , Waste heat recovery system cost COST WHRC and utility costs COST UTILITY ; TAC=COST HEN +COST WHRC +COST UTILITY (64) The inter-plant heat exchanger network cost is given by formula (65), which is mainly composed of fixed cost FIC and area cost AC, where area represents the area of ​​the heat exchanger and α represents the factor for calculating the area cost; COST HEN =FIC+AC×area α (65) The mathematical expression of the waste heat recovery system cost is as shown in formulas (66)-(74), COST EQ Indicates equipment cost, COST TRANS represents the cold energy transportation cost, C represents the cost conversion factor, CRF represents the capital recovery rate, x represents the capital rate, and y represents the service life of the equipment; COST pump Indicates the equipment cost of the pump in the ARC system, COST tur-orc represents the cost of the turbine in the ORC system, COST comp Indicates the cost of the compressor in the ECR system; cost pipe Indicates pipeline cost, cost pump represents the transportation cost, f p,i Indicates flow rate; W pump represents the work done by the pump inside the ARC system, η pump represents the efficiency coefficient of the pump in the ARC system, β pump Indicates the empirical adjustment coefficient of the pump in the ARC system, CPCOST pump represents the economic cost coefficient of the pump in the ARC system, α1 represents the cost factor of the pump in the ARC system; W tur-orc Indicates the work done by the turbine in the ORC system, CPCOST tur-orc represents the economic cost coefficient of the turbine in the ORC system, α2 represents the cost factor of the turbine in the ORC system; W comp Indicates the work done by the compressor in the ECR system, CPCOST comp represents the economic cost coefficient of the compressor in the ECR system, α3 represents the cost factor of the turbine in the ORC system; CPCOST pipe1 、CPCOST pipe2 、CPCOST pipe3 Different economic cost coefficients representing pipeline costs, CPCOST pump1 、CPCOST pump2 、CPCOST pump3 Different economic cost coefficients representing pump transportation costs, binary variables Used to determine whether there is pipeline transportation in the factory; COST WHRC =COST EQ +COST TRANS (66) The mathematical expressions of the utility system costs are shown in Equations (75)-(85), COST GB Indicates the cost of gas boiler, COST EB Indicates the cost of the electric boiler, COST CU Indicates the cost of cooling utilities, COST ELE Indicates electricity cost; COST fuel Indicates fuel cost, COST turbine represents the turbine cost, COST boiler Indicates boiler cost, ratio n A proportional factor representing steam quality, price fuel Indicates fuel price; CPCOST turbine represents the fixed cost of the turbine, OPCOST turbine CPCOST represents the operating cost factor of the turbine; boiler Indicates the fixed cost of gas boiler, OPCOST boiler Indicates the operating cost factor of the gas boiler; COST ebcap Indicates the equipment cost of the electric boiler, COST ebom represents the operating cost of the electric boiler, rate represents the exchange rate, CPCOST eb Indicates the equipment cost factor of the electric boiler, OPCOST eb represents the operating cost factor of the electric boiler; qc represents the total consumption of cold utilities, price cu Indicates the price of cold utility engineering, price buy-ele 、price sale-ele electricity purchase and sale prices; COST UTILITY =COST GB +COST EB +COST CU +COST ELE (75)COST GB =COST fuel +COST turbine +COST boiler (76)COST turbine =CPCOST turbine +OPCOST turbine ×wt total (77) COST fuel =q fuel ×price fuel (79)COST EB =COST ebcap +COST ebom (80) COST ebom =OPCOST eb ×ele eb ×rate×ahour(82)COST CU =qc×price cu (83) COST ELE =(ele buy ×price buy-ele -ele sale ×price sale-ele )×ahour(85)Second stage: In the second phase, the hydrogen supply system is optimized. The relevant configuration parameters optimized in the first phase are fixed, and the hydrogen supply system is optimized on a shorter time scale. Compared to the first-phase model, the second-phase model adds mathematical constraints related to photovoltaic power generation, water electrolysis hydrogen production, hydrogen storage, and electricity storage. The constraint equations for the inter-plant heat exchanger network, waste heat recovery system, and utility system are the same as in the first phase, with only a time index added. In the model, the subscript m∈M represents 24 hours in a day. (1) Constructing a photovoltaic power generation model: The electricity generated by the solar panels, the ORC system, and the turbines are integrated into the park microgrid to meet the various power needs of the park. The energy balance constraints associated with this are shown in equations (86)-(89). represents the electrical energy generated by the photovoltaic panel at time m, IC PV Indicates the number of photovoltaic panels, A PV Represents the area of ​​each photovoltaic panel, represents the efficiency of the photovoltaic panel at time m, G m represents the radiation intensity at time m, η inverter represents the efficiency of the photovoltaic inverter, Indicates the efficiency of photovoltaic panels under standard conditions, β PV represents the temperature coefficient, Indicates the temperature of the photovoltaic panel, T ref Indicates the temperature of photovoltaic panels under standard working conditions. Indicates the ambient temperature of the photovoltaic panel, T noct Indicates the temperature of the photovoltaic panel under normal working conditions, G ref Indicates the radiation intensity of photovoltaic panels under standard conditions, EPV max Indicates the maximum output power of the photovoltaic system; (2) Constructing a battery model: The power balance relationship of the park and the battery charge and discharge constraints are shown in formulas (90)-(95); represents the electrical energy generated by the ORC system at time m, represents the electrical energy generated by the steam extracted by the turbine at time m, represents the electric energy purchased from the external power grid at time m, represents the electric energy released by the battery at time m, represents the electrical energy generated by the photovoltaic panels at time m, represents the electrical energy stored in the battery at time m, represents the electric energy consumed by the electric boiler at time m, represents the power consumed by the ECR system at time m, represents the office electricity demand of the park at time m, represents the electric energy consumed by the electrolytic cell at time m; es m represents the energy storage capacity of the battery at time m, η ch ,η dis Representing the charging and discharging efficiency, using binary variables To judge the state of charge and discharge, only one of them can exist. ch,max 、ele dis,max Indicates the maximum power of charging and discharging; (3) Constructing an electrolyzer model: The park microgrid prioritizes meeting the electricity needs of the ECR system, electric boiler, and office. The remaining electricity is converted into hydrogen through the electrolyzer device. The energy and mass balance equations are shown in Equations (96)-(97); represents the electrical energy converted by the electrolytic cell at time m, η p_h2 Indicates the working efficiency of the electrolytic cell, represents the amount of hydrogen converted at time m, H h2 Indicates the calorific value of hydrogen; (4) Constructing a hydrogen storage tank model: The hydrogen produced by the electrolyzer is used to meet the hydrogen demand of process production on the one hand, and can be mixed with natural gas for combustion on the other hand, and the remaining hydrogen is stored in the hydrogen storage tank; since the second stage considers the combustion of natural gas mixed with hydrogen on the basis of the first stage, the energy balance relationship of the gas boiler needs to be changed to formula (104), and the hydrogen mixing ratio needs to be constrained to be less than or equal to 0.2; The mathematical model of the entire hydrogen storage part is shown in formulas (98)-(106). Indicates the amount of hydrogen released and stored in the hydrogen storage tank at time m, represents the process hydrogen demand at time m, Indicates the amount of hydrogen used to mix with natural gas at time m; HST m Represents the capacity of the hydrogen storage tank at time m, a binary variable Used to judge the status of releasing and storing hydrogen respectively; represents the mass of natural gas consumed by the boiler at time m, represents the volume flow rate of natural gas at time m, ω m Indicates the hydrogen blending ratio of natural gas at time m; 0≤ω m ≤0.2,m∈M (106) (5) Objective function: including the cost of photovoltaic panel equipment COST PV , electrolytic cell equipment cost COST PH2 , Hydrogen storage tank equipment cost COST HST , Battery equipment cost COST BAT , and fuel operating costs COST FUEL , cooling utility operation cost COST CU , operating costs of purchased electricity COST ELE , and in order to achieve low-carbon operation of the entire system, carbon emissions are converted into carbon tax COST ACE Add to the objective function; The specific mathematical expression is shown in formula (107); The calculation formulas for carbon emissions and carbon tax are shown in (108)-(109). The sources of carbon emissions are mainly composed of carbon dioxide generated by fuel combustion and purchased electricity. ACE represents the total carbon emissions, GE represents the total carbon emissions, and ng Indicates the carbon emission factor of fuel combustion, GE ele represents the carbon emission factor of purchased electricity, days represents the number of working days, cct represents the carbon price, represents the amount of natural gas consumed at time m; COST ACE =ACE×cct(109) The calculation formulas for the equipment costs of photovoltaic panels, electrolyzers, hydrogen storage tanks, and batteries are shown in (110)-(113), CPCOST PV 、OPCOST PV The factor representing the equipment cost and operating cost of photovoltaic panels, CPCOST PH2 、OPCOST PH2 Represents the equipment cost and operating cost factor of the electrolytic cell, ele ph2max Indicates the capacity configuration of the electrolytic cell, CPCOST HST Indicates the equipment cost factor of the hydrogen storage tank, HST max Indicates the capacity configuration of the hydrogen storage tank, CPCOST BAT Represents the equipment cost factor of the battery, es max Indicates the capacity configuration of the battery; COST HST =HST max ×CPCOST HST ×CRF(112)COST BAT =es max ×CPCOST BAT ×CRF(113)。

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