Low-carbon economic operation method and system for comprehensive energy system

Abstract

The invention relates to the technical field of comprehensive energy system operation optimization, in particular to a comprehensive energy system low-carbon economic operation method and system.The method comprises the following steps that system total cost minimization serves as a target function, and a stepped carbon transaction mechanism and a Carnot battery are introduced on the basis of a comprehensive energy system energy supply structure; establishing an electric heating integrated energy system optimization scheduling model considering low-carbon economic operation and demand response; and solving the optimal scheduling model of the electric heating comprehensive energy system to obtain a low-carbon economic operation scheme of the electric heating comprehensive energy system. By introducing the Carnot cell and the demand response strategy, the flexibility of electricity-heat supply of the system is improved, effective consumption of new energy such as wind power and photovoltaic energy is promoted, the energy purchase cost of the system is effectively reduced by optimizing the energy purchase strategy, the carbon emission is reduced, and the low-carbon economic operation effect of the system is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated energy system operation optimization, and in particular to a low-carbon economic operation method and system for an integrated energy system. Background Art

[0002] In the context of carbon neutrality, building a low-carbon, clean, and efficient multi-energy complementary energy system has become the key to the development of my country's energy industry. The integrated energy system is widely regarded as an effective solution to promote the transformation of the energy system because it can achieve the coupling and efficient management of multiple energy forms.

[0003] However, there are still some limitations in the operation mode of the existing integrated energy system, especially the cogeneration units are usually subject to the operation mode of "heat-based electricity", which limits the comprehensive utilization efficiency of energy; for example, Wei Zhenbo, Ma Xinru, Guo Yi and others proposed an optimized operation model of an integrated energy system considering demand response under a carbon trading mechanism. Although this model effectively coordinates the economy and low-carbon nature of the system by reasonably allocating the heat production ratio of CHP, since the heat load is mainly provided by CHP, the "heat-based electricity" operation under the condition of meeting the rigid constraints of user heat load in winter leads to excessive CHP power generation, which in turn squeezes out the access to the grid of wind power and photovoltaic clean energy, resulting in a waste of resources of "abandoning wind and abandoning light", and at the same time leads to higher carbon emissions.

[0004] At the same time, the volatility of renewable energy generation such as wind and solar energy has also brought challenges to the stable operation of the power grid, resulting in frequent "wind and solar abandonment" and difficulties in peak load regulation of the power grid. Large-scale energy storage technology is an important support for the current energy system transformation and the realization of dual carbon goals. Large-scale energy storage systems can effectively smooth out the output fluctuations of renewable energy such as wind power and photovoltaics, improve the quality of electricity, and enhance the stability and security of the power grid. However, large-scale energy storage technology also has its limitations, such as the dependence of pumped storage on geographical conditions, the maintenance cost of batteries, and the heat loss during high-temperature molten salt storage, which also restricts the further development of the integrated energy system and the wider consumption of new energy.

[0005] Based on this, how to achieve low-carbon economic operation of the integrated energy system is an issue that needs to be addressed urgently. Summary of the invention

[0006] The purpose of the present invention is to provide a low-carbon economic operation method and system for an integrated energy system, which realizes the low-carbon economic operation of the integrated energy system by introducing a ladder carbon trading mechanism and Carnot batteries on the basis of the integrated energy system and utilizing a demand response strategy.

[0007] The embodiment of the present invention is implemented by the following technical solution: A low-carbon economic operation method of an integrated energy system comprises the following steps:

[0008] Taking the minimization of the total system cost as the objective function, a step-by-step carbon trading mechanism and Carnot batteries are introduced on the basis of the energy supply structure of the integrated energy system to establish an optimal dispatch model for the electric-thermal integrated energy system that takes into account low-carbon economic operation and demand response;

[0009] The optimization dispatching model of the electric-thermal integrated energy system is solved to obtain a low-carbon economic operation plan for the electric-thermal integrated energy system.

[0010] According to a preferred embodiment, the expression of the objective function is as follows:

[0011] minf=C om +C buy +C carbon_trade +C adb

[0012] In the above formula, C om represents the total operation and maintenance cost, C buy represents the cost of purchased energy, C carbon_trade represents the tiered carbon trading cost, C adb Represents the cost of abandoned energy.

[0013] According to a preferred embodiment, the expression of the operation and maintenance cost is as follows:

[0014]

[0015] In the above formula, T represents the operation cycle, Ω represents the device set, ω i represents the operation and maintenance coefficient of equipment i, P i,t represents the output of device i at time t;

[0016] The expression of the purchased energy cost is as follows:

[0017]

[0018] In the above formula, Indicates the power purchased from the upper power grid at time t, represents the electricity purchase price at time t, Q b,t represents the amount of fuel purchased at time t, κ g represents the fuel purchase price at time t;

[0019] The expression of the tiered carbon trading cost is as follows:

[0020]

[0021] In the above formula, E p represents the carbon emissions under the quota carbon emission mechanism, E out represents the actual carbon emissions, α represents the carbon trading base price, E vIndicates the carbon emissions in each interval, E out It is divided into 5 sections, each section is 2000Kg long, and v represents the step section. represents the carbon emission coefficient of equipment i under its operating state, Carbon emission coefficient of equipment i in production and transportation status, P i Indicates the output of device i;

[0022] The expression of the abandoned energy cost is as follows:

[0023]

[0024] In the above formula, C w represents the unit energy abandonment cost, Indicates the amount of abandoned light at time t, Indicates the amount of wind abandoned at time t.

[0025] According to a preferred embodiment, the energy supply structure of the integrated energy system is composed of a power supply path, a heat supply path, a superior gas grid, a cogeneration unit, photovoltaics, a wind turbine unit, an superior power grid, a battery, a Carnot battery, and a first heat pump;

[0026] The cogeneration unit has an input end of the upper gas grid and an output end of the power supply path and the heat supply path, and is an energy supply device that outputs electrical energy and thermal energy in the form of thermoelectric coupling to bear the electrical load and thermal load;

[0027] The output end of the photovoltaic and wind turbine generator sets is a power supply path, serving as an energy supply device that outputs electrical energy and bears electrical loads;

[0028] The output end of the upper power grid is a power supply path, and the output electric energy bears the electric load as a supplementary power supply;

[0029] The battery input and output terminals are both power supply paths, serving as energy storage devices that store electrical energy when set conditions are met;

[0030] The input end of the Carnot battery is a power supply path, and the output end is a power supply path and a heat supply path, and it is an energy storage device that stores electrical energy in the form of heat and outputs electrical energy and heat energy to bear electrical load and heat load when the set conditions are met;

[0031] The first heat pump has an input end that is a power supply path and an output end that is a heat supply path, serving as a supplementary heat source for generating heat energy by consuming electrical energy.

[0032] According to a preferred embodiment, the Carnot battery is composed of a second heat pump, an organic Rankine cycle low-temperature power generation device, a thermal energy storage device, and a solar heat collection tank;

[0033] Among them, the second heat pump power input end is connected to the power supply path, the solar collector heat output end and the second heat pump heat output end are connected to the heat input end of the thermal energy storage device, the first heat output end of the thermal energy storage device is connected to the heat supply path, the second heat output end of the thermal energy storage device is connected to the heat input end of the organic Rankine cycle low-temperature power generation device, and the power output end of the organic Rankine cycle low-temperature power generation device is connected to the power supply path.

[0034] According to a preferred embodiment, the second heat pump is configured to convert surplus electricity into thermal energy and store it in the thermal energy storage device when the electrical load demand of the integrated energy system is lower than a set value;

[0035] The thermal energy storage device is configured to provide thermal energy to the heating path when the thermal load demand of the integrated energy system is higher than a set value, and to provide thermal energy to the organic Rankine cycle low-temperature power generation device when the electrical load demand of the integrated energy system is higher than a set value, and to convert thermal energy into electrical energy through the organic Rankine cycle low-temperature power generation device and provide electrical energy to the power supply path.

[0036] According to a preferred embodiment, the energy loads participating in the demand response on the load side are classified into curtailable electric loads, transferable electric loads, curtailable thermal loads and transferable thermal loads;

[0037] The total change in the load side's participation in the demand response of the load that can be reduced and the load that can be transferred at time t The calculation expression is as follows:

[0038]

[0039] In the above formula, represents the initial electrical load at time t, ρ j represents the electricity price at time j, represents the initial electricity price at time j, E EL(t,j) The electricity price elasticity matrix represents the change in electricity price at time t to time j;

[0040] The total change in the load side's participation in the demand response for heat load that can be reduced and heat load that can be transferred at time t The calculation expression is as follows:

[0041]

[0042] In the above formula, represents the initial heat load at time t, Hp j represents the hot price at time j, represents the initial heat price at time j, E Hl(t,j) The heat price elasticity matrix represents the change in heat price at time t to time j.

[0043] According to a preferred embodiment, the optimization scheduling model of the electric-thermal integrated energy system includes load balance constraints, output upper and lower limit constraints, and energy storage device constraints.

[0044] According to a preferred embodiment, the expression of the load balancing constraint is as follows:

[0045]

[0046] In the above formula, P 发,t represents the system input power at time t, P 耗,t represents the system power consumption at time t, P wp,t represents the photovoltaic power generation power at time t, P pv,t represents the power generated by the wind turbine at time t, represents the electric power of the cogeneration unit at time t, η CHP,P Indicates the electricity conversion efficiency of the cogeneration unit, F t CHP represents the amount of fuel consumed by the cogeneration unit at time t, η discharge Indicates the battery discharge efficiency, P discharge,t Represents the battery discharge power at time t, P e,t represents the external discharge power of the Carnot battery at time t, P HP,t represents the power consumption of the first heat pump at time t, P H,t represents the power consumption of the second heat pump at time t, η eharge Indicates the battery charging efficiency, P charge,t represents the battery charging power at time t, represents the thermal power of the cogeneration unit at time t, η CHP,Q Indicates the thermal conversion efficiency of the combined heat and power unit, COP HP represents the first heat pump refrigeration coefficient, P h,t It represents the heat release power of the Carnot battery at time t;

[0047] The expressions of the output upper and lower limits are as follows:

[0048]

[0049] In the above formula, P wp,F represents the predicted value of photovoltaic resources, P pv,F represents the predicted value of wind power resources, represents the lower limit of the electric power of the cogeneration unit at time t, represents the upper limit of the electric power of the cogeneration unit at time t, represents the lower limit of thermal power of the cogeneration unit at time t, represents the upper limit of the thermal power of the cogeneration unit at time t, P H,min represents the lower limit of the power consumption of the second heat pump at time t, PH,max represents the upper limit of the power consumption of the second heat pump at time t, P e,min represents the lower limit of the external discharge power of the Carnot battery at time t, P e,max represents the upper limit of the external discharge power of the Carnot battery at time t, P h,min P represents the lower limit of the external heat release power of the Carnot battery at time t. h,max P represents the upper limit of the heat release power of the Carnot battery at time t. HP,min represents the lower limit of the power consumption of the first heat pump at time t, P HP,max Indicates the upper limit of the power consumption of the first heat pump at time t;

[0050] The energy storage device constraints include battery constraints and Carnot battery constraints, and the expressions are as follows:

[0051]

[0052] In the above formula, E min Indicates the lower limit of battery capacity, E t represents the battery capacity at time t, E max represents the upper limit of battery capacity, δ represents the self-loss coefficient of the battery, E t-1 Represents the battery capacity at time t-1, H t,min Represents the lower limit of thermal energy storage equipment capacity, H t Represents the capacity of thermal energy storage equipment, H t,max Represents the upper limit of thermal energy storage equipment capacity, H T,t represents the total amount of heat stored in the thermal energy storage device at time t, δ T Represents the self-loss coefficient of thermal energy storage equipment, H T,t-1 Indicates the total amount of heat stored in the thermal energy storage device at time t-1, COP H Indicates the cooling coefficient, P H,t represents the electric energy consumed by the second heat pump at time t, H s,t represents the heat energy collected by the solar collector at time t, P h,t represents the heat release power of the Carnot battery at time t, P O,t P represents the thermal power consumed by the discharge of the organic Rankine cycle low-temperature power generation device at time t, e,t represents the external discharge power of the Carnot battery at time t, η ORC Indicates the power generation efficiency of the organic Rankine cycle low-temperature power generation device.

[0053] The present invention also provides a low-carbon economic operation system for an integrated energy system, which is applied to the method described above, and comprises:

[0054] The model building module is used to take the minimization of the total system cost as the objective function, introduce the ladder carbon trading mechanism and the Carnot battery with solar thermal auxiliary heating on the basis of the energy supply structure of the integrated energy system, and establish an optimization scheduling model for the electric-thermal integrated energy system taking into account low-carbon economic operation and demand response;

[0055] The solution module is used to solve the optimization scheduling model of the electric-thermal integrated energy system to obtain a low-carbon economic operation plan for the electric-thermal integrated energy system.

[0056] The technical solution of a low-carbon economic operation method and system for an integrated energy system provided by an embodiment of the present invention has at least the following advantages and beneficial effects: (1) By introducing Carnot batteries to participate in the operation of the integrated energy system, the flexibility of the electricity-heat supply of the integrated energy system is significantly improved; based on the characteristics of the Carnot battery, wind power is stored during the period of abundant wind resources at night and converted into thermal energy, effectively meeting the higher heat load demand at night, while reducing the wind abandonment rate, and discharging during the peak period of electricity load during the day, helping the integrated energy system to smoothly pass the peak period, thereby enhancing the peak-shaving capacity of the integrated energy system; (2) The introduction of the Carnot battery promotes the consumption of new energy such as wind power and photovoltaics, and reduces the clean energy grid connection caused by the operation of cogeneration units. This change not only reduces carbon emissions, but also reduces the energy purchase and operation costs of the integrated energy system by optimizing the operation strategy of the cogeneration unit, bringing both economic and environmental benefits to the integrated energy system; (3) By constructing a demand response strategy that includes transferable loads and reducible loads, the integrated energy system can achieve peak shaving and valley filling on the load side and smooth the load curve; based on the demand response strategy, the integrated energy system adjusts the energy consumption strategy according to the electricity price in different time periods, optimizes the electricity purchase time, and reduces the energy purchase cost; in addition, the integrated energy system can choose a more economical and less carbon-emitting operation mode in different load periods, further enhancing the low-carbon economic operation effect of the integrated energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic diagram of a process for a low-carbon economic operation method of an integrated energy system provided in Example 1 of the present invention;

[0058] Figure 2 A schematic diagram of the structure of an electric and thermal integrated energy system provided in Example 1 of the present invention;

[0059] Figure 3 The electric and thermal load and predicted resource power curves provided in Example 1 of the present invention;

[0060] Figure 4 The electric power balance diagram of comparative example 2 provided by embodiment 1 of the present invention;

[0061] Figure 5The thermal power balance diagram of comparative example 2 provided in Example 1 of the present invention;

[0062] Figure 6 A comparison curve of power generation and power purchase of the cogeneration units of Comparative Example 1 and Comparative Example 2 provided in Example 1 of the present invention;

[0063] Figure 7 The electric power balance diagram provided by Embodiment 1 of the present invention;

[0064] Figure 8 The comparison curves before and after the electric load demand response provided in Example 1 of the present invention;

[0065] Fig. 9 The heat load demand response before and after comparison curve provided in Example 1 of the present invention;

[0066] Icons: 1. Superior gas grid; 2. Cogeneration unit; 3. Photovoltaic; 4. Wind turbine; 5. Superior power grid; 6. Battery; 7. First heat pump; 8. Second heat pump; 9. Thermal energy storage equipment; 10. Solar collector trough; 11. Organic Rankine cycle low-temperature power generation device. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0068] Example 1

[0069] Figure 1 This is a flow chart of a low-carbon economic operation method of an integrated energy system according to an embodiment of the present invention. Figure 1 As shown, the low-carbon economic operation method of the integrated energy system includes the following steps:

[0070] Step 1: Taking the minimization of the total system cost as the objective function, a step-by-step carbon trading mechanism and Carnot batteries are introduced on the basis of the energy supply structure of the integrated energy system to establish an optimal dispatching model for the electric-thermal integrated energy system that takes into account low-carbon economic operation and demand response;

[0071] Step 2: Use commercial optimization software to solve the optimization scheduling model of the electric-thermal integrated energy system and obtain a low-carbon economic operation plan for the electric-thermal integrated energy system.

[0072] The following is a further explanation of step one:

[0073] Regarding step 1, this embodiment takes the minimum sum of the operation and maintenance cost, energy purchase cost, carbon trading cost, and energy abandonment cost of the integrated energy system as the objective function, and the expression is as follows:

[0074] minf=C om +C buy +C carbon_trade +C adb

[0075] In the above formula, C om represents the total operation and maintenance cost, C buy represents the cost of purchased energy, C carbon_trade represents the tiered carbon trading cost, C adb Represents the cost of abandoned energy.

[0076] The expression of operation and maintenance cost is as follows:

[0077]

[0078] In the above formula, T represents the operating cycle, T = 24, ω i represents the operation and maintenance coefficient of equipment i, P i,t represents the output of device i at time t, Ω represents a device set, and the device set includes a wind turbine 4, a photovoltaic 3, a cogeneration unit 2, a battery 6, a Carnot battery and a first heat pump 7, which will be described in detail later and will not be repeated here.

[0079] The expression of purchased energy cost is as follows:

[0080]

[0081] In the above formula, Indicates the power purchased from the upper grid 5 at time t, represents the electricity purchase price at time t, Q b,t represents the amount of fuel purchased at time t, κ g Represents the fuel purchase price at time t.

[0082] Regarding tiered carbon trading, when the carbon emissions of energy supply equipment are within the given quota, the excess quota can be sold in the carbon trading market to obtain income; when the actual carbon emissions exceed the quota, additional carbon emission quotas must be purchased at a tiered price. The expression of the tiered carbon trading cost is as follows:

[0083]

[0084] In the above formula, E p represents the carbon emissions under the quota carbon emission mechanism, E out represents the actual carbon emissions, α represents the carbon trading base price, E v Indicates the carbon emissions in each interval, Eout It is divided into 5 sections, each section is 2000Kg long, υ represents the step section, represents the carbon emission coefficient of equipment i under its operating state, Carbon emission coefficient of equipment i in production and transportation status, P i Indicates the device output.

[0085] The expression of energy abandonment cost is as follows:

[0086]

[0087] In the above formula, C w represents the unit energy abandonment cost, Indicates the amount of abandoned light at time t, Indicates the amount of wind abandoned at time t.

[0088] More specifically, see Figure 2 As shown, the energy supply structure of the integrated energy system is composed of a power supply path, a heat supply path, an upper gas grid 1, a cogeneration unit 2, a photovoltaic 3, a wind turbine 4, an upper grid 5, a storage battery 6, a Carnot battery and a first heat pump 7;

[0089] Among them, the input end of the cogeneration unit 2 is the upper gas grid 1, and the output end is the power supply path and the heat supply path, which is used as an energy supply device that outputs electric energy and thermal energy in the form of thermoelectric coupling to bear the electric load and thermal load; the output ends of the photovoltaic 3 and wind turbine 4 are power supply paths, which are used as energy supply devices that output electric energy to bear the electric load; the output end of the upper power grid 5 is the power supply path, which outputs electric energy to bear the electric load as a supplementary power supply; the input and output ends of the battery 6 are both power supply paths, which is used as an energy storage device that stores electric energy when the set conditions are met;

[0090] The input end of the Carnot battery is a power supply path, and the output end is a power supply path and a heat supply path, and it is an energy storage device that stores electrical energy in the form of heat and outputs electrical energy and heat energy to bear electrical load and heat load when the set conditions are met;

[0091] It should be noted that, as an energy storage device, the Carnot battery stores electrical energy in the form of heat and then discharges the heat energy through the Carnot cycle. Compared with the battery 6, the battery 6 can be both charged and discharged; and the charging process of the Carnot battery is that the heat pump consumes electrical energy to absorb heat from a low-temperature heat source (generally waste heat) and converts it into a high-temperature heat source and stores it in the thermal energy storage device 9, which is equivalent to the charging process of the battery 6; the discharging process of the Carnot battery is that the heat energy stored in the thermal energy storage device 9 is converted into electrical energy and released through the Carnot cycle, which is equivalent to the discharging process of the battery 6. Therefore, the capacity of the battery 6 corresponds to the capacity of the thermal energy storage device 9.

[0092] The first heat pump 7 has an input end for power supply and an output end for heat supply, serving as a supplementary heat source for generating heat energy by consuming electrical energy.

[0093] It should be noted that the new energy power generation part in the integrated energy system provided in this embodiment includes wind turbines 4 and photovoltaics 3, aiming to make full use of renewable resources and improve the cleanliness and sustainability of energy; the cogeneration unit 2 plays a core role in providing heat load and electric load, and provides supplementary heat load through the first heat pump 7 to enhance the heat supply capacity of the integrated energy system. In addition, the integrated energy system also integrates Carnot batteries and storage batteries 6 as energy storage devices to optimize the storage and release of energy.

[0094] In the electric-thermal integrated energy system provided in this embodiment, the Carnot battery is composed of a second heat pump 8 , an organic Rankine cycle low-temperature power generation device 11 , a thermal energy storage device 9 and a solar thermal collector 10 .

[0095] The electric energy input end of the second heat pump 8 is connected to the power supply path, and the heat energy output end of the second heat pump 8 is connected to the heat energy input end of the thermal energy storage device 9; the second heat pump 8 is configured to convert the surplus electricity into heat energy and store it in the thermal energy storage device 9 when the electric load demand of the integrated energy system is lower than the set value; in this embodiment, the second heat pump 8 extracts current from the energy supply path and converts it into heat according to the real-time electric load and heat load demand of the system, and effectively stores it in the thermal energy storage device 9; for example, when the electric load demand of the integrated energy system is at a low point, especially during periods when the electricity market price is low, or when there is excess clean energy generation and it cannot be connected to the grid, the second heat pump 8 will intervene to convert the surplus electricity into heat energy, and then store it in the thermal energy storage device 9; in addition, during the period when wind resources are relatively abundant at night, wind power is stored through the Carnot battery, and the second heat pump 8 is used to convert wind power into heat energy, which effectively meets the higher heat load demand at night and reduces the wind abandonment rate.

[0096] The heat output end of the solar thermal collector 10 is connected to the heat input end of the thermal energy storage device 9. The solar thermal collector 10 utilizes abundant light and heat resources to transfer the collected heat energy to the thermal energy storage device 9 through an efficient heat-conducting medium as a supplementary heat source for the system, thereby improving the efficiency of the Carnot battery.

[0097] The first heat energy output end of the thermal energy storage device 9 is connected to the heat supply path; the thermal energy storage device 9 is configured to provide heat energy supply to the heat supply path when the heat load demand of the integrated energy system is higher than the set value; in the present embodiment, when the integrated energy system faces a higher heat load demand, the heat energy in the thermal energy storage device 9 will be mobilized to meet the heating demand of the heat load; it should be noted that since the Carnot battery stores electricity and releases heat, "thermal and electric decoupling" is achieved, so the use of Carnot batteries for heating has better economy.

[0098] The second heat energy output end of the thermal energy storage device 9 is connected to the heat energy input end of the organic Rankine cycle low-temperature power generation device 11, and the electric energy output end of the organic Rankine cycle low-temperature power generation device 11 is connected to the power supply path; the thermal energy storage device 9 is also configured to provide heat energy supply to the organic Rankine cycle low-temperature power generation device 11 when the electric load demand of the integrated energy system is higher than the set value, and convert the heat energy into electric energy through the organic Rankine cycle low-temperature power generation device 11 and provide the electric energy supply to the power supply path; in this embodiment, the discharge of the Carnot battery during the peak period of electric load during the daytime helps the integrated energy system to smoothly pass the peak period, thereby enhancing the peak-shaving capacity of the integrated energy system.

[0099] Based on the above-mentioned flexible thermal energy management strategy, the fixed mode of "heat determines electricity" of the traditional cogeneration unit 2 is broken, and the cogeneration unit 2 is given greater operation flexibility and energy utilization efficiency; through this optimized energy flow management, the integrated energy system can respond to grid demand more intelligently, realize efficient energy utilization and maximize cost-effectiveness.

[0100] The demand response strategy considered in this embodiment is further described below:

[0101] In this embodiment, the energy loads participating in the demand response on the load side are classified into the following categories: curtailable electric loads, transferable electric loads, curtailable heat loads, and transferable heat loads; the total change in the demand response of curtailable electric loads and transferable electric loads on the load side at time t is The calculation expression is as follows:

[0102]

[0103] In the above formula, represents the initial electrical load at time t, ρ j represents the electricity price at time j, represents the initial electricity price at time j, E EL(t,j) The electricity price elasticity matrix represents the change in electricity price at time t to time j.

[0104] The total change in the load side's participation in the demand response for heat load that can be reduced and heat load that can be transferred at time t The calculation expression is as follows:

[0105]

[0106] In the above formula, represents the initial heat load at time t, Hp j represents the hot price at time j, represents the initial heat price at time j, E HL(t,j) The heat price elasticity matrix represents the change in heat price at time t to time j.

[0107] Furthermore, the constraint conditions for the design of the optimal scheduling model for the electric-thermal integrated energy system in this embodiment include load balance constraints, output upper and lower limit constraints, and energy storage device constraints.

[0108] The expression of load balancing constraint is as follows:

[0109]

[0110] In the above formula, P 发,t represents the system input power at time t, P 耗,t represents the system power consumption at time t, P wp,t represents the power generated by photovoltaic 3 at time t, P pv,t represents the power generated by wind turbine 4 at time t, represents the electric power of cogeneration unit 2 at time t, η CHP,P represents the electricity conversion efficiency of the combined heat and power unit 2, represents the amount of fuel consumed by the cogeneration unit 2 at time t, η discharge represents the discharge efficiency of battery 6, P discharge,t represents the discharge power of battery 6 at time t, P e,t represents the external discharge power of the Carnot battery at time t, P HP,t represents the power consumption of the first heat pump 7 at time t, P H,t represents the power consumption of the second heat pump 8 at time t, η charge represents the charging efficiency of the battery 6, P charge,t represents the charging power of battery 6 at time t, represents the thermal power of CHP unit 2 at time t, η CHP,Q Indicates the thermal conversion efficiency of the combined heat and power unit 2, COP HP represents the refrigeration coefficient of the first heat pump 7, P h,t It represents the heat release power of the Carnot battery at time t.

[0111] The expressions of output upper and lower limits are as follows:

[0112]

[0113] In the above formula, P wp,F represents the predicted value of photovoltaic resources, P pv,F represents the predicted value of wind power resources, Indicates the lower limit of the electric power of the cogeneration unit 2 at time t, Indicates the upper limit of the electric power of the cogeneration unit 2 at time t, Indicates the lower limit of thermal power of cogeneration unit 2 at time t, represents the upper limit of thermal power of CHP unit 2 at time t, P H,min represents the lower limit of the power consumption of the second heat pump 8 at time t, P H,maxrepresents the upper limit of the power consumption of the second heat pump 8 at time t, P e,min represents the lower limit of the external discharge power of the Carnot battery at time t, P e,max represents the upper limit of the external discharge power of the Carnot battery at time t, P h,min P represents the lower limit of the external heat release power of the Carnot battery at time t. h,max P represents the upper limit of the heat release power of the Carnot battery at time t. HP,min represents the lower limit of the power consumption of the first heat pump 7 at time t, P HP,max Indicates the upper limit of the power consumption of the first heat pump 7 at time t.

[0114] The energy storage device constraints include battery constraints and Carnot battery constraints, and the expressions are as follows:

[0115]

[0116] In the above formula, E min Indicates the lower limit of battery 6 capacity, W t represents the capacity of battery 6 at time t, E max represents the upper limit of the capacity of the battery 6, δ represents the self-loss coefficient of the battery 6, E t-1 Indicates the capacity of battery 6 at time t-1, H t,min Indicates the lower limit of the capacity of thermal energy storage equipment 9, H t Indicates the capacity of thermal energy storage equipment 9, H t,max Indicates the upper limit of the capacity of the thermal energy storage device 9, H T,t represents the total amount of heat stored in the thermal energy storage device 9 at time t, δ T represents the self-loss coefficient of the thermal energy storage device 9, H T,t-1 represents the total amount of heat stored in the thermal energy storage device 9 at time t-1, COP H Indicates the cooling coefficient, P H,t represents the electric energy consumed by the second heat pump 8 at time t, H s,t represents the heat energy collected by the solar collector 10 at time t, P h,t represents the heat release power of the Carnot battery at time t, P O,t represents the thermal power consumed by the discharge of the organic Rankine cycle low-temperature power generation device 11 at time t, P e,t represents the external discharge power of the Carnot battery at time t, η ORC It shows the power generation efficiency of the organic Rankine cycle low-temperature power generation device 11 .

[0117] The following is an explanation of the example analysis of this embodiment for the above scheme: In this example analysis, the electric-thermal integrated energy system provided by the above scheme is taken as the research object, that is, Figure 1 The structure of the electric and thermal integrated energy system is shown in the figure. This example analysis considers both electric and thermal loads. The typical daily load curve in winter can be found in Figure 3As shown, there are two clean energy sources including wind turbine 4 and photovoltaic 3; two energy storage devices including battery 6 and Carnot battery; a heat and power cogeneration unit 2 including "thermal and electric coupling" as a device for simultaneous power supply and heat supply; and a first heat pump 7 as a supplementary heating device. The first heat pump 7, the heat and power cogeneration unit 2, the battery 6, the Carnot battery, the time-of-use electricity price and other related parameters are shown in Table 1 and Table 2:

[0118] Table 1. Model parameters

[0119]

[0120] Table 2. Time-of-use electricity prices

[0121]

[0122] This scheme considers step-by-step carbon trading, demand response and the participation of Carnot batteries. The designed comparison examples include: Comparison example 1, which considers step-by-step carbon trading, does not consider demand response, and does not consider the participation of Carnot batteries; Comparison example 2, which considers the participation of Carnot batteries on the basis of comparison example 1. Comparison examples 1, 2 and this scheme are explained in the following scenarios 1, 2 and 3.

[0123] Table 3. Comparison of scheduling results in different scenarios

[0124] Scenario 1 2 3 Operation and maintenance cost / yuan 711.19 760.33 717.07 Energy purchase cost / yuan 4603.56 3738.46 3335.09 Carbon trading cost / yuan 124.26 70.42 78.79 Abandoned energy cost / yuan 323.30 0.00 0.00 Load income / yuan 14383.61 14383.61 14780.18 Profit / yuan 8621.29 9814.40 10649.23 Actual carbon emissions / kg 8141.44 6823.16 6286.53

[0125] As shown in Table 3, compared with scenario 1 and scenario 2, the carbon trading cost of scenario 2 is reduced by 43.33%, and the actual carbon emissions are reduced by 1318.28kg. This is because the heat load of scenario 1 is mainly provided by cogeneration unit 2. In winter, the heat load of cogeneration unit 2 is operated under the condition of satisfying the rigid constraints of user heat load. The power generation capacity of cogeneration unit 2 is too high, which squeezes out the access to the grid of wind power and photovoltaic clean energy, resulting in the waste of resources of "abandoning wind and photovoltaic", and at the same time leading to high carbon emissions; while scenario 2 introduces Carnot batteries, adds energy storage equipment, can store wind power and photovoltaic that cannot be connected to the grid due to the crowding out of cogeneration unit 2, increase the use of clean energy, and thus reduce carbon emissions; at the same time, due to the participation of Carnot batteries in heating, the heat supply of cogeneration unit 2 is reduced, resulting in a reduction in the power generation capacity of cogeneration unit 2, further increasing the access to the grid of wind power and photovoltaic, resulting in the abandonment cost of scenario 2 being reduced by 323.30 yuan compared with the abandonment cost of scenario 1, and the level of new energy consumption is improved. Although the operation and maintenance costs of the integrated energy system increased due to the addition of equipment after the introduction of Carnot batteries, the operating power of the cogeneration unit 2 was reduced, the energy purchase cost was reduced, and the carbon trading cost and energy abandonment cost were reduced. As a result, the overall accounting increased the income of the integrated energy system by 13.84%.

[0126] Comparing Scenario 2 and Scenario 3, the energy purchase cost of Scenario 3 is reduced by 10.79%. This is because under the demand response operation strategy, users adjust their energy use strategies according to the time-of-use pricing of different energy sources, transfer part of the load during high electricity price periods to low electricity price periods and reduce part of the load energy use, reducing the peak load, making the electric load and thermal load curves smoother, so that the system can choose a more economical way to purchase energy; at the same time, under the demand response operation strategy, the benefits of bearing electric and thermal loads are different in different load periods, which makes the benefits of bearing loads increase by 2.76% compared with Scenario 2; considering the demand response under the carbon trading mechanism, the system compares the electricity and gas purchase costs and the output of cogeneration unit 2 and clean energy in different periods, and thus chooses a more economical way to operate with less carbon emissions, so that the energy purchase cost, operation and maintenance cost, and carbon emissions of Scenario 3 are all lower than those of Scenario 2, and the benefits of Scenario 3 are 8.51% higher than those of Scenario 2.

[0127] To verify the feasibility of adding Carnot batteries to the integrated energy system, the electrical power balance diagram and thermal power balance diagram of scenario 2 are shown in the figure below: Figure 4 , Figure 5 As shown. During the night time period of 23:00-6:00, the integrated energy system has a lower demand for electric load and a higher demand for heat load. Different from the traditional heating mode of cogeneration unit 2 in scenario 1, after the participation of the Carnot battery, the wind power that is abundant at night but cannot be connected to the grid due to the occupation of cogeneration unit 2 can be converted into high-priced heat energy, which not only ensures a higher heat load supply at night, but also reduces the wind abandonment rate; at night, due to the low demand for electric load and sufficient electricity, the excess electricity is stored in the battery 6. When the demand for electric load is high during the day, the electricity stored in the battery 6 is released, which can reduce the amount of electricity purchased during peak hours and reduce the cost of electricity purchase; at night, the demand for electric load is low and the demand for heat load is high. The Carnot battery converts the excess electricity into heat energy, which not only reduces the output power of the cogeneration unit 2, but also increases the consumption of new energy, while also reducing carbon emissions and energy purchase costs. After the Carnot battery participates in operation, it discharges to the outside when the electricity load demand is high during the day, thereby helping the cogeneration unit 2 to pass through the peak period of electricity load more smoothly, increasing the peak-shaving capacity of the cogeneration unit 2, and reducing the energy purchase cost and operation cost of the cogeneration unit 2; the Carnot battery only discharges a small amount during peak hours and operates in a heating mode during other periods. This is because the round-trip efficiency of the Carnot battery is relatively low, only 0.2-0.4, so the Carnot battery operates in an external heating mode most of the time and does not participate in external discharge.

[0128] from Figure 6The comparative analysis of the power generation of cogeneration unit 2 in scenarios 1 and 2 shows that when the Carnot battery is not involved in the operation of scenario 1, the power curve of cogeneration unit 2 is consistent with the real-time thermal load curve, and the operation is carried out in a "heat-to-power" manner. After the Carnot battery is involved in the operation of scenario 2, the power generation of cogeneration unit 2 is reduced, and the power generation curve and the thermal load curve are no longer consistent, the "thermal-electric coupling" of the gas turbine is alleviated, and the flexibility of cogeneration unit 2 is increased; at the same time, the power generation of cogeneration unit 2 is reduced from 23:00 to 15:00, the access to the grid of new energy is increased, the energy purchase cost and operation cost of the gas turbine are reduced, and the carbon emissions are reduced, which is conducive to improving the economy and flexibility of the operation of the integrated energy system. After the Carnot battery is involved in the operation, the power purchase amount during the peak period of 17:00-21:00 is reduced, and the power purchase time is shifted to the valley period of 23:00, so that the integrated energy system can choose a more economical way to purchase electricity, reduce the energy purchase cost of the integrated energy system, and improve the economy of the system.

[0129] Scenario 3: Electric load before and after demand response Figure 8 As shown. Figure 8 It can be seen that compared with the obvious peak-valley distribution of the original load, after demand response, part of the load is reduced in the high electricity price period (08:00-13:00, 19:00-23:00) and transferred to the low electricity price period (23:00-08:00), reducing the load in the high electricity price period and increasing the load in the low electricity price period, making the load curve smooth and achieving peak shaving and valley filling. In addition, it can be seen from Table 3 that the use of demand response strategy can reduce the operating cost and carbon emission level of the integrated energy system, thereby achieving the effect of energy conservation, emission reduction and increased benefits. The analysis of thermal load is similar to this, see Fig. 9 The power balance diagram after demand response is shown in Figure 7 As shown in the figure, compared with the power balance diagram before demand response, it can be seen that after adopting the demand response strategy, the power purchase time of the integrated energy system is concentrated in the valley period (23:00-08:00) with low electricity prices, so that the system chooses a more economical way to purchase electricity. From Table 3, it can be seen that the system's energy purchase cost is reduced by 10.79% under the demand response strategy.

[0130] After analyzing the above examples, the following conclusions can be drawn:

[0131] (1) By introducing Carnot batteries to participate in the operation of the integrated energy system, the flexibility of the electricity-heat supply of the integrated energy system has been significantly improved; based on the characteristics of Carnot batteries, wind power is stored during the night when wind resources are relatively abundant and converted into heat energy, effectively meeting the higher heat load demand at night, while reducing the wind abandonment rate. The discharge during the peak period of electricity load during the day helps the integrated energy system to smoothly pass the peak period, thereby enhancing the peak-shaving capacity of the integrated energy system;

[0132] (2) The introduction of Carnot batteries has promoted the consumption of new energy sources such as wind power and photovoltaic power 3, and reduced the problem of clean energy grid-connected space being squeezed out by the operation of cogeneration unit 2. This change not only reduces carbon emissions, but also reduces the energy purchase cost and operation cost of the integrated energy system by optimizing the operation strategy of cogeneration unit 2, bringing both economic and environmental benefits to the integrated energy system.

[0133] (3) By constructing a demand response strategy that includes transferable loads and reducible loads, the integrated energy system can achieve peak shaving and valley filling on the load side and smooth the load curve; based on the demand response strategy, the integrated energy system adjusts the energy consumption strategy according to the electricity price in different time periods, optimizes the electricity purchase time, and reduces the energy purchase cost; in addition, the integrated energy system can choose a more economical and less carbon-emitting operating mode in different load periods, further enhancing the low-carbon economic operation effect of the integrated energy system.

[0134] Example 2

[0135] This embodiment provides a low-carbon economic operation system for an integrated energy system based on the technical solution provided in Embodiment 1, which is applied to the method in Embodiment 1, including:

[0136] The model building module is used to take the minimization of the total system cost as the objective function, introduce the ladder carbon trading mechanism and the Carnot battery with solar thermal auxiliary heating on the basis of the energy supply structure of the integrated energy system, and establish an optimization scheduling model for the electric-thermal integrated energy system taking into account low-carbon economic operation and demand response;

[0137] The solution module is used to solve the optimization scheduling model of the electric-thermal integrated energy system and obtain a low-carbon economic operation plan for the electric-thermal integrated energy system.

[0138] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low-carbon economic operation method for an integrated energy system, characterized in that: The steps include: Taking the minimization of the total system cost as the objective function, a step-by-step carbon trading mechanism and Carnot batteries are introduced on the basis of the energy supply structure of the integrated energy system to establish an optimal dispatch model for the electric-thermal integrated energy system that takes into account low-carbon economic operation and demand response; The optimization dispatching model of the electric-thermal integrated energy system is solved to obtain a low-carbon economic operation plan for the electric-thermal integrated energy system.

2. The low-carbon economic operation method of the integrated energy system according to claim 1, characterized in that: The expression of the objective function is as follows: minf=C om +C buy +C carbon_trade +C adb In the above formula, C om represents the total operation and maintenance cost, C buy represents the cost of purchased energy, C carbon_trade represents the tiered carbon trading cost, C adb Represents the cost of abandoned energy.

3. The low-carbon economic operation method of the integrated energy system according to claim 2, characterized in that: The expression of the operation and maintenance cost is as follows: In the above formula, T represents the operation cycle, Ω represents the device set, ω i represents the operation and maintenance coefficient of equipment i, P i,t represents the output of device i at time t; The expression of the purchased energy cost is as follows: In the above formula, represents the power purchased from the upper grid (5) at time t, represents the electricity purchase price at time t, Q b,t represents the amount of fuel purchased at time t, κ g represents the fuel purchase price at time t; The expression of the tiered carbon trading cost is as follows: In the above formula, E p represents the carbon emissions under the quota carbon emission mechanism, E out represents the actual carbon emissions, α represents the carbon trading base price, E v Indicates the carbon emissions in each interval, E out It is divided into 5 sections, each section is 2000Kg long, υ represents the step section, represents the carbon emission coefficient of equipment i under its operating state, Carbon emission coefficient of equipment i in production and transportation status, P i Indicates the output of device i; The expression of the abandoned energy cost is as follows: In the above formula, C w represents the unit energy abandonment cost, Indicates the amount of abandoned light at time t, Indicates the amount of wind abandoned at time t.

4. The low-carbon economic operation method of the integrated energy system according to claim 1, characterized in that: The energy supply structure of the comprehensive energy system is composed of a power supply path, a heat supply path, a superior gas network (1), a cogeneration unit (2), a photovoltaic unit (3), a wind turbine unit (4), an superior power grid (5), a storage battery (6), a Carnot battery and a first heat pump (7); The cogeneration unit (2) has an input end that is the upper gas grid (1) and an output end that is a power supply path and a heat supply path, and is an energy supply device that outputs electrical energy and thermal energy in the form of thermoelectric coupling to bear electrical load and thermal load; The output ends of the photovoltaic (3) and wind turbine (4) groups are power supply paths, serving as energy supply equipment that outputs electrical energy and bears electrical loads; The output end of the upper power grid (5) is a power supply path, and the output electric energy bears the electric load as a supplementary power supply; The input end and the output end of the storage battery (6) are both power supply paths, and serve as an energy storage device for storing electric energy when set conditions are met; The input end of the Carnot battery is a power supply path, and the output end is a power supply path and a heat supply path, and it is an energy storage device that stores electrical energy in the form of heat and outputs electrical energy and heat energy to bear electrical load and heat load when the set conditions are met; The first heat pump (7) has an input end for power supply and an output end for heat supply, serving as a supplementary heat source for generating heat energy by consuming electrical energy.

5. The low-carbon economic operation method of the integrated energy system according to claim 4, characterized in that: The Carnot battery is composed of a second heat pump (8), an organic Rankine cycle low-temperature power generation device (11), a thermal energy storage device (9) and a solar heat collection tank (10); The electric energy input end of the second heat pump (8) is connected to the power supply path, the heat energy output end of the solar heat collecting tank (10) and the heat energy output end of the second heat pump (8) are connected to the heat energy input end of the thermal energy storage device (9), the first heat energy output end of the thermal energy storage device (9) is connected to the heat supply path, the second heat energy output end of the thermal energy storage device (9) is connected to the heat energy input end of the organic Rankine cycle low-temperature power generation device (11), and the electric energy output end of the organic Rankine cycle low-temperature power generation device (11) is connected to the power supply path.

6. The low-carbon economic operation method of the integrated energy system according to claim 5, characterized in that: The second heat pump (8) is configured to convert surplus electricity into thermal energy and store it in the thermal energy storage device (9) when the electrical load demand of the integrated energy system is lower than a set value; The thermal energy storage device (9) is configured to provide thermal energy to the heating path when the thermal load demand of the integrated energy system is higher than a set value, and to provide thermal energy to the organic Rankine cycle low-temperature power generation device (11) when the electrical load demand of the integrated energy system is higher than a set value, and to convert thermal energy into electrical energy through the organic Rankine cycle low-temperature power generation device (11) and provide electrical energy to the power supply path.

7. The low-carbon economic operation method of the integrated energy system according to any one of claims 1 to 6, characterized in that: Classify the energy loads participating in demand response on the load side, including curtailable electric loads, transferable electric loads, curtailable thermal loads and transferable thermal loads; The total change in the load side's participation in the demand response of the load that can be reduced and the load that can be transferred at time t The calculation expression is as follows: In the above formula, represents the initial electrical load at time t, ρ j represents the electricity price at time j, represents the initial electricity price at time j, E EL(t,j) The electricity price elasticity matrix represents the change in electricity price at time j at time t; The total change in the load side's participation in the demand response for heat load that can be reduced and heat load that can be transferred at time t The calculation expression is as follows: In the above formula, represents the initial heat load at time t, Hp j represents the hot price at time j, represents the initial heat price at time j, E HL(t,j) The heat price elasticity matrix represents the change in heat price at time t to time j.

8. The low-carbon economic operation method of the integrated energy system according to claim 5, characterized in that: The optimization scheduling model of the electric-thermal integrated energy system includes load balance constraints, output upper and lower limit constraints, and energy storage device constraints.

9. The low-carbon economic operation method of the integrated energy system according to claim 8, characterized in that: The expression of the load balancing constraint is as follows: In the above formula, P 发,t represents the system input power at time t, P 耗,t represents the system power consumption at time t, P wp,t represents the photovoltaic (3) power generation at time t, P pv,t represents the power generated by the wind turbine (4) at time t, represents the electric power of the cogeneration unit (2) at time t, η CHP,P represents the electricity conversion efficiency of the combined heat and power unit (2), represents the amount of fuel consumed by the cogeneration unit (2) at time t, η discharge represents the discharge efficiency of the battery (6), P discharge,t represents the discharge power of the battery (6) at time t, P e,t represents the external discharge power of the Carnot battery at time t, P HP,t represents the power consumption of the first heat pump (7) at time t, P H,t represents the power consumption of the second heat pump (8) at time t, η charge represents the charging efficiency of the battery (6), P charge,t represents the charging power of the battery (6) at time t, represents the thermal power of the cogeneration unit (2) at time t, η CHP,Q Indicates the thermal conversion efficiency of the combined heat and power unit (2), COP HP represents the refrigeration coefficient of the first heat pump (7), P h,t It represents the heat release power of the Carnot battery at time t; The expressions of the output upper and lower limits are as follows: In the above formula, P wp,F represents the predicted value of photovoltaic resources, P pv,F represents the predicted value of wind power resources, represents the lower limit of the electric power of the cogeneration unit (2) at time t, represents the upper limit of the electric power of the cogeneration unit (2) at time t, represents the lower limit of the thermal power of the cogeneration unit (2) at time t, represents the upper limit of the thermal power of the cogeneration unit (2) at time t, P H,min represents the lower limit of the power consumption of the second heat pump (8) at time t, P H,max represents the upper limit of the power consumption of the second heat pump (8) at time t, P e,min represents the lower limit of the external discharge power of the Carnot battery at time t, P e,max represents the upper limit of the external discharge power of the Carnot battery at time t, P h,min P represents the lower limit of the external heat release power of the Carnot battery at time t. h,max P represents the upper limit of the heat release power of the Carnot battery at time t. HP,min represents the lower limit of the power consumption of the first heat pump (7) at time t, P HP,max represents the upper limit of the power consumption of the first heat pump (7) at time t; The energy storage device constraints include battery constraints and Carnot battery constraints, and the expressions are as follows: In the above formula, E min Indicates the lower limit of battery (6) capacity, E t represents the capacity of the battery (6) at time t, E max represents the upper limit of the capacity of the battery (6), δ represents the self-loss coefficient of the battery (6), E t-1 represents the capacity of the battery (6) at time t-1, H t,min represents the lower capacity limit of the thermal energy storage device (9), H t represents the capacity of the thermal energy storage device (9), H t,max represents the upper limit of the capacity of the thermal energy storage device (9), H T,t represents the total amount of heat stored in the thermal energy storage device (9) at time t, δ T represents the self-loss coefficient of the thermal energy storage device (9), H T,t-1 represents the total amount of heat stored in the thermal energy storage device (9) at time t-1, COP H Indicates the cooling coefficient, P H,t represents the electric energy consumed by the second heat pump (8) at time t, H s,t represents the heat energy collected by the solar collector (10) at time t, P h,t represents the heat release power of the Carnot battery at time t, P O,t represents the thermal power consumed by the organic Rankine cycle low-temperature power generation device (11) at time t, P e,t represents the external discharge power of the Carnot battery at time t, η ORC Indicates the power generation efficiency of the organic Rankine cycle low-temperature power generation device (11).

10. A low-carbon economic operation system for an integrated energy system, applied to the method according to any one of claims 1 to 9, characterized in that: include: The model building module is used to take the minimization of the total system cost as the objective function, introduce the ladder carbon trading mechanism and the Carnot battery with solar thermal auxiliary heating on the basis of the energy supply structure of the integrated energy system, and establish an optimization scheduling model for the electric-thermal integrated energy system taking into account low-carbon economic operation and demand response; The solution module is used to solve the optimization scheduling model of the electric-thermal integrated energy system to obtain a low-carbon economic operation plan for the electric-thermal integrated energy system.

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