CN112861335B - P2G and energy storage-containing low-carbon economic dispatching method for comprehensive energy system - Google Patents

Abstract

The invention discloses a low-carbon economic dispatching method for a comprehensive energy system containing P2G and stored energy, which introduces an operation mechanism and a carbon transaction mechanism of electric-to-gas equipment into a comprehensive energy system model of a multi-energy coupling unit so as to reduce the operation cost of the comprehensive energy system. Firstly, comprehensively considering the characteristics of all units in the comprehensive energy system, constructing a regional comprehensive energy system combined scheduling structure comprising electric-to-gas equipment P2G, energy source equipment, storage equipment and conversion equipment, analyzing the working mechanism of the electric-to-gas equipment P2G and establishing a carbon transaction model of the electric-to-gas equipment; secondly, establishing a comprehensive energy system optimization operation model considering carbon trading cost with the aim of maximizing system operation profit; finally, the simulation case verifies that the proposed model can reduce the economic cost of the system when participating in the carbon trading market, thereby reducing the dependence of the comprehensive energy system on the external market and having higher feasibility and economy.

Description

A low-carbon economic scheduling method for an integrated energy system including P2G and energy storage

technical field

The invention belongs to the technical field of operation optimization of an integrated energy system, and specifically relates to a low-carbon economic scheduling method for an integrated energy system including P2G and energy storage.

Background technique

In recent years, China's renewable energy industry has developed rapidly. As of the end of June 2020, the national renewable energy (wind/light) installed capacity reached 433 million kilowatts. However, due to the unbalanced distribution of wind and solar resources, the high cost of grid investment and operation and maintenance, and the imperfect market trading mechanism, my country's renewable energy is currently in the predicament of low utilization efficiency, insufficient investment returns, and weak market competitiveness. With the rapid development of renewable energy, the pressure of traditional direct financial subsidies is increasing.

In order to alleviate the plight of renewable energy, P2G (power to gas, P2G), as the core link in IES, can convert the remaining wind power that cannot be absorbed in low valleys into natural gas and combine energy storage system (ESS) and Various energy conversion devices (such as combined cooling, heating and power, CCHP) are interconnected to achieve strong coupling between the combined cooling and heating systems, thereby improving the flexibility of system operation and enhancing its absorption of wind power capacity, and the emergence of the carbon trading market enables power-to-gas not only to absorb wind power, but also to participate in carbon trading, reduce the economic cost of the comprehensive energy system, reduce carbon emissions, and better guide the healthy development of society.

Contents of the invention

Technical problem: The technical problem to be solved by the present invention is to provide a method that considers the use cost constraints of the integrated energy system, considers the constraints of the operating characteristics of each equipment in the integrated energy system, and considers the carbon reduction economic benefits of each equipment in the integrated energy system , a low-carbon economic scheduling method for integrated energy systems including power-to-gas equipment P2G and energy storage that reduces the operation and maintenance costs of integrated energy systems.

Technical solution: In order to solve the above technical problems, the present invention proposes a low-carbon economic scheduling method for the operation of an integrated energy system including P2G and energy storage, including the following steps:

Step 10) Establish an integrated energy system operation optimization model, including gas turbines, gas boilers, power-to-gas equipment P2G, batteries, electric refrigerators, electric boilers, waste heat boilers, heat exchange devices, heat storage tanks, wind turbines and photovoltaic units;

Step 20) Establishing a model of the power-to-gas equipment operation mechanism participating in the carbon trading mechanism;

Step 30) Add the power-to-gas equipment operation mechanism participating in carbon trading mechanism model established in step 20) to the integrated energy system operation optimization model established in step 10).

In the described step 10), the process of establishing an integrated energy system operation optimization model is:

Step 101) Establish the output cost model in the integrated energy system operation optimization model, wherein, the integrated energy system IES purchase fuel cost model is formula (1):

为m台联供燃气轮机GT共同发电功率；

为n台燃气锅炉GB共同产热功率；α，β，γ为燃气轮机GT燃料成本系数；η_GB为燃气锅炉GB的产热效率；Δt为调度时段步长；In formula (1), f _gas is the price per unit calorific value of purchased fuel;

Co-generated power for m sets of gas turbines GT;

is the common heat production power of n gas-fired boilers GB; α, β, γ are the fuel cost coefficients of gas turbine GT; η _GB is the heat production efficiency of gas-fired boiler GB; Δt is the step size of the scheduling period;

The integrated energy system IES power purchase cost and grid interaction cost are shown in formulas (2) and (3):

分别表示t时段系统向大电网购电、售电的价格，用分段函数表示如式(3)所示；P_t,grid为t时段综合能源系统IES与大电网交换的功率；In the above formula, f _t,grid is the exchange power price of the integrated energy system IES in the t period. When the value is greater than 0, it means that the integrated energy system IES purchases electricity from the large power grid; when it is less than 0, it means that the integrated energy system IES sells electricity to the large grid. electricity for profit,

Respectively represent the price of electricity purchased and sold by the system from the large power grid during the period t, expressed as a piecewise function as shown in formula (3); P _t,grid is the power exchanged between the integrated energy system IES and the large power grid during the period t;

The formula for the operating cost of the energy storage device ESS in the integrated energy system IES is:

为t时段蓄电池ES的充放电功率；

为t时段蓄热槽HS的充放热功率；f_cap为蓄电池ES的容量；In the above formula: the cost of each charge and discharge of the battery ES is the same, then f _r is the cost of a single complete charge and discharge of the battery ES, f _pur is the purchase price, and M _cyc is the number of charge and discharge;

is the charging and discharging power of the battery ES in the period t;

is the charging and discharging power of the heat storage tank HS during the period t; f _cap is the capacity of the battery ES;

The formula for IES operation and maintenance cost of integrated energy system is formula (6):

In the formula, K _i is the IES maintenance and operation cost coefficient of the integrated energy system; P _i,t is the output of the i-th equipment in the period t;

The formula of IES carbon transaction cost of integrated energy system is formula (7):

F _t,ct ＝f _co2 (-M _p2g -M _p )P _t,p2g +f _c (M _GT -M _m )P _t,GT formula (7)

In the above formula, f _co2 and f _c represent the price coefficient of purchasing CO ₂ and the price coefficient of carbon emission; M _GT is the carbon emission intensity of gas turbine GT, and M _m is its carbon emission allocation; P _t,GT is The power generation of the gas turbine GT in the period t;

Step 102) Establish the operation constraint model of each equipment in the IES operation optimization model of the integrated energy system, wherein the electrical bus balance equation is formula (8):

P _t,WT +P _t,PV +P _t,GT +P _t,grid +P _t,ES,D -P _t,P2G -P _t,ER -P _t,EB -P _t,ES,C -L _{t, E} = 0 Formula (8)

In formula (8), P _t,WT , P _t,PV represent the output kW of the fan unit and the photovoltaic unit during the period t; P _t,GT represents the electric power output by the gas turbine during the period _t ; P _t,ES,C , P _t,ES,D respectively represent the charging and discharging power of the battery during the t period; P _{t ,P2G} represent the electric power input by the power-to-gas equipment P2G during the t period; The electric power input by the refrigerator; P _{t, EB} represents the electric power input by the electric heating boiler during the t period; L _{t, E} represents the user's electric load during the t period;

The air bus balance equation is formula (9):

η _ER Q _t,ER -L _t,C ＝0 Formula (9)

In formula (9), η _ER is the cooling efficiency of the absorption refrigerator; Q _t,ER represents the cooling power of the refrigerator during the t period; L _t,C represents the cooling load of the user during the t period;

The balance equation of the flue gas busbar is formula (10):

η _GT P _t,GT -Q _t,WH ＝0 Formula (10)

In formula (10), η _GT is the heat production efficiency of the gas turbine; Q _t,WH represents the heat production output of the waste heat boiler during the period t;

The steam bus balance equation is formula (11):

η _WH Q _t,WH +Q _t,GB +Q _t,HS,D -Q _t,HS,C -Q _t,HX ＝0 Formula (11)

In formula (11), η _WH is the conversion efficiency of the waste heat boiler; Q _t,GB represents the heat production power of the gas-fired boiler during the t period; Q _t,HS,C and Q _t,HS,D represent the heat storage capacity Heat storage and discharge power;

The hot water bus balance equation is formula (12):

η _HX Q _t,HX -L _t,H ＝0 Formula (12)

In the formula (12): η _HX is the conversion efficiency of the heat exchanger; Q _t,HX represents the heat output of the heat exchanger in the period t; L _t,H represents the heat load of the user in the period t;

The interactive state constraints of the integrated energy system IES and the grid are expressed as formula (13):

In the formula, P _max,buy and P _max,sell represent the maximum power _purchase and sale of the integrated energy system _IES to the grid, respectively; state, the two are mutually exclusive;

The P2G constraint of power-to-gas equipment is formula (14):

In formula (14), P _{min, P2G} , P _{max, P2G} respectively represent the minimum value and maximum value of the P2G working power kW of the power-to-gas equipment; R _{down, P2G} , R _{up, P2G} represent the lower limit of the climbing rate of the power consumption with cap.

The constraint of gas turbine GT is formula (15):

In formula (15), P _min,GT , P _max,GT represent the minimum and maximum working power of gas turbine GT respectively; R _down,GT , R _up,GT represent the lower limit and upper limit of the ramp rate of the output power respectively;

The constraints of wind turbines and photovoltaic generators are formula (16):

和

分别表示风电机组和光伏机组的预测出力；In formula (16), P _PV,t and P _WT,t are the actual output of the wind turbine and photovoltaic generator at time t, respectively;

and

represent the predicted output of wind turbines and photovoltaic units, respectively;

The battery constraint is formula (17):

表示蓄电池充放电功率的下限；

表示蓄电池充放电功率的上限kW；U_ES,C表示蓄电池充电状态的标记位，1为充电，0为停止充电；U_ES,D表示蓄电池放电状态的标记位，1为放电，0为停止放电；W(T+1)、W(T)分别表示蓄电池在T+1与T时间段的荷电状态；W_max、W_min为蓄电池荷电状态的上下限；η_ES,C、η_ES,D分别表示蓄电池充放电效率；σ_ES为蓄电池自放电率；In formula (17),

Indicates the lower limit of battery charging and discharging power;

Indicates the upper limit kW of the charging and discharging power of the battery; U _{ES, C} indicates the flag bit of the battery charging state, 1 means charging, 0 means stop charging; U _{ES, D} means the flag bit of the battery discharging state, 1 means discharging, 0 means stop discharging ; W(T+1), W(T) represent the state of charge of the battery in T+1 and T time periods respectively; W _max , W _min are the upper and lower limits of the state of charge of the battery; η _ES,C , η _{ES, D} respectively represent the charging and discharging efficiency of the battery; σ _ES is the self-discharging rate of the battery;

The heat storage tank is constrained by formula (18):

分别为蓄热槽充放热功率的最大值与最小值；U_HS,C、U_HS,D分别为蓄热槽充放热的状态变量；E(T+1)、E(T)分别表示蓄热槽在T+1与T时间段的容量；E_max、E_min为蓄热槽容量的上下限；η_HS,C、η_HS,D分别表示蓄热槽充放热效率；б_HS为蓄热槽热量耗散率。In formula (18),

are the maximum and minimum values of the heat storage tank charging and discharging power; U _HS,C , U _HS,D are the state variables of the heat storage tank charging and discharging; The capacity of the heat storage tank in the T+1 and _T time periods; E _{max and} E _min are the upper and lower _limits of the capacity of the heat storage tank; Heat sink heat dissipation rate.

In the step 20), the specific process of establishing the P2G operation mechanism of the power-to-gas equipment to participate in the carbon trading model is as follows:

Step 201), establish the reaction principle in the P2G operation mechanism of the power-to-gas equipment as shown in formula (19):

The volume of CH ₄ generated after the methane reaction is the same as the volume of CO ₂ consumed before the reaction, and CO ₂ is an indispensable raw material in the reaction process and needs to be purchased from the carbon trading market, so the power-to-gas equipment P2G unit electricity consumption The amount of CO ₂ and the cost of purchasing CO ₂ during period t are shown in equations (20) and (21):

In the above formula, ρ _co2 is the density of CO ₂ ; η _p2g is the conversion efficiency of the power-to-gas equipment P2G; P _t,p2g is the electric energy consumed by the power-to-gas equipment P2G during the period t, t=1,2,3..., T is the number of time slots in the IES scheduling cycle of the integrated energy system; L _CH4 is the combustion calorific value of methane, which is 36MJ/m ³ ; f _co2 is the price coefficient for purchasing CO ₂ ;

Step 202), the cost of establishing P2G equipment to participate in the carbon trading market is shown in formula (22):

f _p2g ＝f _co2 (-M _p2g -M _p )P _t,p2g formula (22)

In formula (22), M _p is the carbon emission quota of P2G equipment per unit of electric energy. Since there is no carbon emission during the operation of the equipment, the value is 0.

In the step 30), the power-to-gas equipment P2G operation mechanism and carbon trading model established in step 20) are added to the integrated energy system operation optimization model established in step 10) to establish a low-carbon economy with the goal of maximum profit The scheduling model is shown in formula (23):

In formula (23), T is the number of time slots in the IES scheduling period of the integrated energy system; F _t,gas is the fuel purchase cost of the IES in the t period; F _t,grid is the interaction cost between the IES and the external power grid in the t period; F _t,ess is the operating cost of the energy storage device ESS in the integrated energy system IES in the period t; F _t,om is the operation and maintenance cost of each equipment in the integrated energy system IES in the period t; F _t,ct is the cost of the IES in the integrated energy system in the period t Participate in carbon trading fees.

Beneficial effects: Compared with the prior art, the present invention has the following advantages: The present invention builds a low-carbon economic scheduling method for an integrated energy system containing renewable energy that considers power-to-gas equipment P2G and energy storage, and converts power-to-gas equipment P2G Participate in the carbon trading market with gas turbines to conduct transactions, and build a low-carbon economic scheduling model. The problems that the present invention can solve are: 1. The integrated energy system with energy storage can be decoupled by the energy storage device ESS in the "cogeneration" system. The coupling relationship between heat and electricity realizes load complementarity and energy transformation, and meets the needs of the system's electricity, heat, and gas loads; 2. By analyzing and comparing the scenes before and after the introduction of carbon trading in the power-to-gas equipment P2G in the proposed model, it is obtained The model can effectively consider the system economy and low carbon, and effectively reduce the economic cost of the integrated energy system, so that the optimal configuration of the integrated energy system is more in line with the actual requirements, which is of great significance for promoting energy conservation and emission reduction and the future development of new energy.

Description of drawings

Figure 1 is a schematic diagram of the energy flow of the integrated energy system IES including the power-to-gas equipment P2G;

Figure 2 is a schematic diagram illustrating the P2G production process of the power-to-gas equipment;

Figure 3 is the output forecast curve of fan unit and photovoltaic unit in the integrated energy system IES;

Figure 4 is the time-of-use power purchase price curve of the integrated energy system;

Figure 5 is a schematic diagram of the optimal balance state of electric loads in the integrated energy system IES;

Fig. 6 is a schematic diagram of the optimal balance state of heat load in the integrated energy system IES.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be described in detail below in combination with the accompanying drawings and implementation examples. It should be understood that the specific implementation cases described here are only used to explain the present invention, and are not intended to limit the invention.

The invention provides a low-carbon economic scheduling method for an integrated energy system including P2G and energy storage, comprising the following steps:

Step 10) Establish an integrated energy system operation optimization model, including gas turbines, gas boilers, power-to-gas equipment P2G, batteries, electric refrigerators, electric boilers, waste heat boilers, heat exchange devices, heat storage tanks, wind turbines and photovoltaic units;

Step 20) Establishing a model of the power-to-gas equipment operation mechanism participating in the carbon trading mechanism;

Step 30) Add the power-to-gas equipment operation mechanism participating in carbon trading mechanism model established in step 20) to the integrated energy system operation optimization model established in step 10).

In the described step 10), the process of establishing an integrated energy system operation optimization model is:

Step 101) Establish the output cost model in the integrated energy system operation optimization model, wherein, the integrated energy system IES purchase fuel cost model is formula (1):

为m台联供燃气轮机GT共同发电功率；

为n台燃气锅炉GB共同产热功率；α，β，γ为燃气轮机GT燃料成本系数；η_GB为燃气锅炉GB的产热效率；Δt为调度时段步长；In formula (1), f _gas is the price per unit calorific value of purchased fuel;

Co-generated power for m sets of gas turbines GT;

is the common heat production power of n gas-fired boilers GB; α, β, γ are the fuel cost coefficients of gas turbine GT; η _GB is the heat production efficiency of gas-fired boiler GB; Δt is the step size of the scheduling period;

The integrated energy system IES power purchase cost and grid interaction cost are shown in formulas (2) and (3):

分别表示t时段系统向大电网购电、售电的价格，用分段函数表示如式(3)所示；P_t,grid为t时段综合能源系统IES与大电网交换的功率；In the above formula, f _t,grid is the exchange power price of the integrated energy system IES in the t period. When the value is greater than 0, it means that the integrated energy system IES purchases electricity from the large power grid; when it is less than 0, it means that the integrated energy system IES sells electricity to the large grid. electricity for profit,

Respectively represent the price of electricity purchased and sold by the system from the large power grid during the period t, expressed as a piecewise function as shown in formula (3); P _t,grid is the power exchanged between the integrated energy system IES and the large power grid during the period t;

The formula for the operating cost of the energy storage device ESS in the integrated energy system IES is:

为t时段蓄电池ES的充放电功率；

为t时段蓄热槽HS的充放热功率；f_cap为蓄电池ES的容量；In the above formula: the cost of each charge and discharge of the battery ES is the same, then f _r is the cost of a single complete charge and discharge of the battery ES, f _pur is the purchase price, and M _cyc is the number of charge and discharge;

is the charging and discharging power of the battery ES in the period t;

is the charging and discharging power of the heat storage tank HS during the period t; f _cap is the capacity of the battery ES;

The formula for IES operation and maintenance cost of integrated energy system is formula (6):

In the formula, K _i is the IES maintenance and operation cost coefficient of the integrated energy system; P _i,t is the output of the i-th equipment in the period t;

The formula of IES carbon transaction cost of integrated energy system is formula (7):

F _t,ct ＝f _co2 (-M _p2g -M _p )P _t,p2g +f _c (M _GT -M _m )P _t,GT formula (7)

In the above formula, f _co2 and f _c represent the price coefficient of purchasing CO ₂ and the price coefficient of carbon emission; M _GT is the carbon emission intensity of gas turbine GT, and M _m is its carbon emission allocation; P _t,GT is The power generation of the gas turbine GT in the period t;

Step 102) Establish the operation constraint model of each equipment in the IES operation optimization model of the integrated energy system, wherein the electrical bus balance equation is formula (8):

P _t,WT +P _t,PV +P _t,GT +P _t,grid +P _t,ES,D -P _t,P2G -P _t,ER -P _t,EB -P _t,ES,C -L _{t, E} = 0 Formula (8)

In formula (8), P _t,WT , P _t,PV respectively represent the output of the fan unit and the photovoltaic unit during the t period; P _{t ,GT} represents the electric power output by the gas turbine during the t period; Exchange power; P _{t, ES, C} , P _{t, ES, D} respectively represent the charging and discharging power of the battery during the t period; P _{t , P2G} represent the electric power input by the power-to-gas equipment P2G during the t period; The input electric power; P _{t, EB} represents the electric power input by the electric heating boiler during the t period; L _{t, E} represents the user's electric load during the t period;

The air bus balance equation is formula (9):

η _ER Q _t,ER -L _t,C ＝0 Formula (9)

In formula (9), η _ER is the cooling efficiency of the absorption refrigerator; Q _t,ER represents the cooling power of the refrigerator during the t period; L _t,C represents the cooling load of the user during the t period;

The balance equation of the flue gas busbar is formula (10):

η _GT P _t,GT -Q _t,WH ＝0 Formula (10)

In formula (10), η _GT is the heat production efficiency of the gas turbine; Q _t,WH represents the heat production output of the waste heat boiler during the period t;

The steam bus balance equation is formula (11):

η _WH Q _t,WH +Q _t,GB +Q _t,HS,D -Q _t,HS,C -Q _t,HX ＝0 Formula (11)

In formula (11), η _WH is the conversion efficiency of the waste heat boiler; Q _t,GB represents the heat production power kW of the gas-fired boiler in the t period; Q _t,HS,C , Q _t,HS,D represent the heat storage tank in the t period heat storage and discharge power;

The hot water bus balance equation is formula (12):

η _HX Q _t,HX -L _t,H ＝0 Formula (12)

In the formula (12): η _HX is the conversion efficiency of the heat exchanger; Q _t,HX represents the heat output of the heat exchanger in the period t; L _t,H represents the heat load of the user in the period t;

The interactive state constraints of the integrated energy system IES and the grid are expressed as formula (13):

In the formula, P _max,buy and P _max,sell represent the maximum power _purchase and sale of the integrated energy system _IES to the grid, respectively; state, the two are mutually exclusive;

The P2G constraint of power-to-gas equipment is formula (14):

In formula (14), P _{min, P2G} , P _{max, P2G} respectively represent the minimum value and maximum value of the P2G working power kW of the power-to-gas equipment; R _{down, P2G} , R _{up, P2G} represent the lower limit of the climbing rate of the power consumption with cap.

The constraint of gas turbine GT is formula (15):

In formula (15), P _min,GT , P _max,GT represent the minimum and maximum working power of gas turbine GT respectively; R _down,GT , R _up,GT represent the lower limit and upper limit of the ramp rate of the output power respectively;

The constraints of wind turbines and photovoltaic generators are formula (16):

和

分别表示风电机组和光伏机组的预测出力；In formula (16), P _PV,t and P _WT,t are the actual output of the wind turbine and photovoltaic generator at time t, respectively;

and

represent the predicted output of wind turbines and photovoltaic units, respectively;

The battery constraint is formula (17):

表示蓄电池充放电功率的下限；

表示蓄电池充放电功率的上限；U_ES,C表示蓄电池充电状态的标记位，1为充电，0为停止充电；U_ES,D表示蓄电池放电状态的标记位，1为放电，0为停止放电；W(T+1)、W(T)分别表示蓄电池在T+1与T时间段的荷电状态；W_max、W_min为蓄电池荷电状态的上下限；η_ES,C、η_ES,D分别表示蓄电池充放电效率；σ_ES为蓄电池自放电率；In formula (17),

Indicates the lower limit of battery charging and discharging power;

Indicates the upper limit of the charging and discharging power of the battery; U _{ES, C} indicates the flag bit of the charging state of the battery, 1 means charging, 0 means stop charging; U _{ES, D} means the flag bit of the battery discharging state, 1 means discharging, 0 means stop discharging; W(T+1) and W(T) represent the state of charge of the battery in the time period T+1 and T respectively; W _max and W _min are the upper and lower limits of the state of charge of the battery; η _ES,C , η _ES,D Respectively represent the charging and discharging efficiency of the battery; σ _ES is the self-discharging rate of the battery;

The heat storage tank is constrained by formula (18):

分别为蓄热槽充放热功率的最大值与最小值；U_HS,C、U_HS,D分别为蓄热槽充放热的状态变量；E(T+1)、E(T)分别表示蓄热槽在T+1与T时间段的容量；E_max、E_min为蓄热槽容量的上下限；η_HS,C、η_HS,D分别表示蓄热槽充放热效率；б_HS为蓄热槽热量耗散率。In formula (18),

are the maximum and minimum values of the heat storage tank charging and discharging power; U _HS,C , U _HS,D are the state variables of the heat storage tank charging and discharging; The capacity of the heat storage tank in the T+1 and _T time periods; E _{max and} E _min are the upper and lower _limits of the capacity of the heat storage tank; Heat sink heat dissipation rate.

In the step 20), the specific process of establishing the P2G operation mechanism of the power-to-gas equipment to participate in the carbon trading model is as follows:

Step 201), establish the reaction principle in the P2G operation mechanism of the power-to-gas equipment as shown in formula (19):

The volume of CH ₄ generated after the methane reaction is the same as the volume of CO ₂ consumed before the reaction, and CO ₂ is an indispensable raw material in the reaction process and needs to be purchased from the carbon trading market, so the power-to-gas equipment P2G unit electricity consumption The amount of CO ₂ and the cost of purchasing CO ₂ during period t are shown in equations (20) and (21):

In the above formula, ρ _co2 is the density of CO ₂ ; η _p2g is the conversion efficiency of the power-to-gas equipment P2G; P _t,p2g is the electric energy consumed by the power-to-gas equipment P2G during the period t, t=1,2,3..., T is the number of time slots in the IES scheduling cycle of the integrated energy system; L _CH4 is the combustion calorific value of methane, which is 36MJ/m ³ ; f _co2 is the price coefficient for purchasing CO ₂ ;

Step 202), the cost of establishing P2G equipment to participate in the carbon trading market is shown in formula (22):

f _p2g ＝f _co2 (-M _p2g -M _p )P _t,p2g formula (22)

In formula (22), M _p is the carbon emission quota of P2G equipment per unit of electric energy. Since there is no carbon emission during the operation of the equipment, the value is 0.

In the step 30), the power-to-gas equipment P2G operation mechanism and carbon trading model established in step 20) are added to the integrated energy system operation optimization model established in step 10) to establish a low-carbon economy with the goal of maximum profit The scheduling model is shown in formula (23):

In formula (23), T is the number of time slots in the IES scheduling period of the integrated energy system; F _t,gas is the fuel purchase cost of the IES in the t period; F _t,grid is the interaction cost between the IES and the external power grid in the t period; F _t,ess is the operating cost of the energy storage device ESS in the integrated energy system IES in the period t; F _t,om is the operation and maintenance cost of each equipment in the integrated energy system IES in the period t; F _t,ct is the cost of the IES in the integrated energy system in the period t Participate in carbon trading fees.

Example

As shown in Figures 1 to 6, this embodiment establishes a low-carbon economic dispatch model for a comprehensive energy system including power-to-gas equipment P2G and energy storage, and introduces the operation mechanism of power-to-gas equipment and the carbon trading system into the comprehensive energy of multi-energy coupling units In the system model, analyze the optimization of supply and consumption between energy storage and energy storage, and compare it with the traditional comprehensive energy system operation optimization method, analyze the system operation cost after introducing the carbon trading system, and verify the P2G and storage system proposed by the present invention. The effectiveness of low-carbon economic dispatching methods for integrated energy systems in reducing system operating costs.

Firstly, the comprehensive energy system of a park with renewable energy power generation in a certain area is selected as the simulation object. The system includes power-to-gas equipment P2G, 3 gas turbines GT, fan unit WT, photovoltaic unit PV, heat storage tank HS, battery ES, waste heat boiler WH , electric refrigerator ER, electric boiler EB, heat exchange unit HX, gas boiler GB and other devices, the production efficiency (γ _(P2G) ) of the power-to-gas equipment P2G in normal operation is 0.6, and the maximum operating power is 150kW; the price of carbon emissions is 0.2 yuan/kg, the allocation of carbon emissions is 0.5kg/(kW h), and the price coefficient of CO ₂ is 380 yuan/t; the carbon emission intensity of gas turbine GT is 0.5kg/(kW h), and the dispatched The total length of the period is 24h, the scheduling time Δt is 1h, and the operation and maintenance cost is 0.1 yuan/kW; the operation and maintenance cost of other equipment is 0.02 yuan/kW. The relevant basic parameters of the main equipment in the combined cooling, heating and power system CCHP are given in Table 1. Assuming that the price of natural gas is 3.45 yuan/m ² , the simulation is carried out based on the established optimal dispatching model.

Table 1 The capacity and parameters of each equipment in the system

In order to verify the superiority of the optimized operation of the integrated energy system considering the power-to-gas equipment P2G and energy storage, the calculation example operation results of the integrated energy system IES in the park are analyzed. Uncertainty in efficiency will not be taken into account.

In connection with the analysis of the power purchase price curve, it can be seen from Figure 5 that: during the period from 22:00 to 06:00, the electricity price and load are at a low point, the WT output of the fan unit gradually increases, and most of the electric energy is supplied to the electric boiler EB, and the electric load The integrated energy system purchases electricity from the grid to meet the needs of users. During the period from 07:00 to 12:00, as the electricity price and load gradually rise, the output of the gas turbine GT increases, and the battery ES starts to provide energy to the integrated energy system to make up for the dependence on the grid, and the system begins to send power back to the grid Optimize operating costs by making profits; during 13:00-17:00, electricity prices and loads gradually decrease, and gas turbine GT output gradually decreases; during 17:00-18:00 is the off-duty peak period, power consumption increases, The electricity price increases, and the working condition of the IES is similar to that of the 07:00-12:00 period; during the 19:00-23:00 period, both the electricity price and the load gradually decrease.

The supply and consumption of thermal energy in the integrated energy system IES are waste heat boilers, gas boilers and heat storage tanks. Figure 6 shows the optimization of thermal load power supply in the integrated energy system IES. It can be seen from Figure 6 that the system can meet the demand of thermal load during the scheduling period. During the period from 22:00 to 06:00, the electric boiler EB is mainly used to meet the heat load demand. During the period from 07:00 to 11:00, the output of the gas turbine GT is increased to realize cogeneration of heat and power. Hot tank HS storage. During 12:00-16:00 and 19:00-22:00, the electricity price and load gradually decrease, the output of the gas turbine GT decreases, the heat energy provided by the integrated energy system IES decreases, and the heat storage tank HS releases energy to the integrated energy system IES; During the period of 17:00-18:00, the working conditions of the integrated energy system IES are basically the same as those of the period of 07:00-11:00.

In order to verify the advantages of considering the carbon trading optimization of power-to-gas equipment P2G combined energy storage devices in the integrated energy system, two scenarios were set up to compare the scheduling optimization results of the integrated energy system under the condition of carbon trading.

Scenario 1: Regardless of the carbon trading mechanism, the integrated energy system operates in a coupled manner based on heat and electricity.

Scenario 2: Considering the carbon trading mechanism, the electricity load of the integrated energy system is given priority to supply with renewable energy.

The operating costs of the integrated energy system under the above two operating modes are shown in Table 2. In Scenario 1, the power-to-gas equipment P2G in the integrated energy system does not participate in carbon trading. Considering the volatility of renewable energy, the power load in the system is given priority to supply by gas turbines, the consumption of renewable energy is less, and the total operating cost of the system is relatively low. high. In Scenario 2, the integrated energy system gives priority to the consumption of renewable energy, and the power-to-gas equipment participates in carbon trading, which removes the output constraints of gas turbines and realizes the consumption of renewable energy, with obvious benefits.

Table 2 Total cost of system operation under different scenarios

It can be seen from Table 2 that under typical winter conditions, the total operating costs of the system in Scenario 1 and Scenario 2 are 30,115 yuan and 27,618 yuan, respectively. Compared with Scenario 1, the total operating cost of the system in Scenario 2 is reduced. It can be seen that the integrated energy system including P2G equipment can realize the coordinated use of energy, reduce carbon emissions, and still ensure that the system operation has good economy. This is Due to the combination of power-to-gas equipment P2G, the comprehensive energy system can consume renewable energy on a large scale, thereby reducing the demand for fuel, selling carbon emission rights in the carbon trading market, and then reducing carbon emissions, so that energy can be distributed in space and time By introducing the heat storage tank HS, making full use of the electricity price of the peak-valley time difference, breaking the coupling relationship of heat-fixed electricity in the traditional system "cogeneration", removing the output limitation of the gas turbine GT, and realizing the coordinated distribution of heat energy, effectively Improve energy utilization efficiency; at the same time, it can reduce the output of gas boiler GB, further reduce carbon emissions, and optimize the total operating cost of the system at all times. Therefore, the comprehensive energy system optimization model including power-to-gas equipment P2G and energy storage proposed in the present invention can satisfy the lowest operating cost of the system while reducing carbon emissions and achieve the optimal operation strategy for each unit scheduling of system constraints, that is, the realization of Joint dispatch of electricity-heat-gas.

Claims (1)

1. A low-carbon economic dispatching method for an integrated energy system containing P2G and energy storage, characterized in that, the dispatching method comprises the following steps: Step 10) Establish an integrated energy system operation optimization model, including gas turbines, gas boilers, power-to-gas equipment P2G, batteries, electric refrigerators, electric boilers, waste heat boilers, heat exchange devices, heat storage tanks, wind turbines and photovoltaic units; Step 20) Establishing a model of the power-to-gas equipment operation mechanism participating in the carbon trading mechanism; Step 30) Add the power-to-gas equipment operation mechanism model established in step 20) to participate in the carbon trading mechanism model into the integrated energy system operation optimization model established in step 10); In the described step 10), the process of establishing an integrated energy system operation optimization model is: Step 101) Establish the output cost model in the integrated energy system operation optimization model, wherein, the integrated energy system IES purchase fuel cost model is formula (1):

In formula (1), f _gas is the price per unit calorific value of purchased fuel;

Co-generated power for m sets of gas turbines GT;

is the common heat production power of n gas-fired boilers GB; α, β, γ are the fuel cost coefficients of gas turbine GT; η _GB is the heat production efficiency of gas-fired boiler GB; Δt is the step size of the scheduling period; The integrated energy system IES power purchase cost and grid interaction cost are shown in formulas (2) and (3):

In the above formula, f _t,grid is the exchange power price of the integrated energy system IES in the t period. When the value is greater than 0, it means that the integrated energy system IES purchases electricity from the large power grid; when it is less than 0, it means that the integrated energy system IES sells electricity to the large grid. electricity for profit,

Respectively represent the price of electricity purchased and sold by the system from the large power grid during the period t, expressed as a piecewise function as shown in formula (3); P _t,grid is the power exchanged between the integrated energy system IES and the large power grid during the period t; The formula for the operating cost of the energy storage device ESS in the integrated energy system IES is:

In the above formula: the cost of each charge and discharge of the battery ES is the same, then f _r is the cost of a single complete charge and discharge of the battery ES, f _pur is the purchase price, and M _cyc is the number of charge and discharge;

is the charging and discharging power of the battery ES in the period t;

is the charging and discharging power of the heat storage tank HS during the period t; f _cap is the capacity of the battery ES; The formula for IES operation and maintenance cost of integrated energy system is formula (6):

In the formula, K _i is the IES maintenance and operation cost coefficient of the integrated energy system; P _i,t is the output of the i-th equipment in the period t; The formula of IES carbon transaction cost of integrated energy system is formula (7): F _t,ct ＝f _co2 (-M _p2g -M _p )P _t,p2g +f _c (M _GT -M _m )P _t,GT formula (7) In the above formula, f _co2 and f _c represent the price coefficient of purchasing CO ₂ and the price coefficient of carbon emission; M _GT is the carbon emission intensity of gas turbine GT, and M _m is its carbon emission allocation; P _t,GT is The power generation of the gas turbine GT in the period t; Step 102) Establish the operation constraint model of each equipment in the IES operation optimization model of the integrated energy system, wherein the electrical bus balance equation is formula (8): P _t,WT +P _t,PV +P _t,GT +P _t,grid +P _t,ES,D -P _t,P2G -P _t,ER -P _t,EB -P _t,ES,C -L _{t, E} = 0 Formula (8) In formula (8), P _t,WT , P _t,PV respectively represent the output of the fan unit and the photovoltaic unit during the t period; P _{t ,GT} represents the electric power output by the gas turbine during the t period; Exchange power; P _{t, ES, C} , P _{t, ES, D} respectively represent the charging and discharging power of the battery during the t period; P _{t , P2G} represent the electric power input by the power-to-gas equipment P2G during the t period; The input electric power; P _{t, EB} represents the electric power input by the electric heating boiler during the t period; L _{t, E} represents the user's electric load during the t period; The air bus balance equation is formula (9): η _ER Q _t,ER -L _t,C ＝0 Formula (9) In formula (9), η _ER is the cooling efficiency of the absorption refrigerator; Q _t,ER represents the cooling power of the refrigerator during the t period; L _t,C represents the cooling load of the user during the t period; The balance equation of the flue gas busbar is formula (10): η _GT P _t,GT -Q _t,WH ＝0 Formula (10) In formula (10), η _GT is the heat production efficiency of the gas turbine; Q _t,WH represents the heat production output of the waste heat boiler during the period t; The steam bus balance equation is formula (11): η _WH Q _t,WH +Q _t,GB +Q _t,HS,D -Q _t,HS,C -Q _t,HX ＝0 Formula (11) In formula (11), η _WH is the conversion efficiency of the waste heat boiler; Q _t,GB represents the heat production power of the gas-fired boiler during the t period; Q _t,HS,C and Q _t,HS,D represent the heat storage capacity Heat storage and discharge power; The hot water bus balance equation is formula (12): η _HX Q _t,HX -L _t,H ＝0 Formula (12) In the formula (12): η _HX is the conversion efficiency of the heat exchanger; Q _t,HX represents the heat output of the heat exchanger in the period t; L _t,H represents the heat load of the user in the period t; The interactive state constraints of the integrated energy system IES and the grid are expressed as formula (13):

In the formula, P _max,buy and P _max,sell represent the maximum power _purchase and sale of the integrated energy system _IES to the grid, respectively; state, the two are mutually exclusive; The P2G constraint of power-to-gas equipment is formula (14):

In formula (14), P _{min, P2G} , P _{max, P2G} respectively represent the minimum value and maximum value of the P2G working power kW of the power-to-gas equipment; R _{down, P2G} , R _{up, P2G} represent the lower limit of the climbing rate of the power consumption with upper limit; The constraint of gas turbine GT is formula (15):

In _formula (15), P _min,GT , P _max,GT represent the minimum and maximum working power of gas turbine GT respectively; R down, _GT , R _up,GT represent the lower limit and upper limit of the ramp rate of the output power respectively ; The constraints of wind turbines and photovoltaic generators are formula (16):

In formula (16), P _PV,t and P _WT,t are the actual output of the wind turbine and photovoltaic generator at time t, respectively;

and

represent the predicted output of wind turbines and photovoltaic units, respectively; The battery constraint is formula (17):

In formula (17),

Indicates the lower limit of battery charging and discharging power;

Indicates the upper limit of the charging and discharging power of the battery; U _{ES, C} indicates the flag bit of the charging state of the battery, 1 means charging, 0 means stop charging; U _{ES, D} means the flag bit of the battery discharging state, 1 means discharging, 0 means stop discharging; W(T+1) and W(T) represent the state of charge of the battery in the time period T+1 and T respectively; W _max and W _min are the upper and lower limits of the state of charge of the battery; η _ES,C , η _ES,D Respectively represent the charging and discharging efficiency of the battery; σ _ES is the self-discharging rate of the battery; The heat storage tank is constrained by formula (18):

In formula (18),

are the maximum and minimum values of the heat storage tank charging and discharging power; U _HS,C , U _HS,D are the state variables of the heat storage tank charging and discharging; The capacity of the heat storage tank in the T+1 and _T time periods; E _{max and} E _min are the upper and lower _limits of the capacity of the heat storage tank; heat sink heat dissipation rate; In the step 20), the specific process of establishing the P2G operation mechanism of the power-to-gas equipment to participate in the carbon trading model is as follows: Step 201), establish the reaction principle in the P2G operation mechanism of the power-to-gas equipment as shown in formula (19):

The volume of CH ₄ generated after the methane reaction is the same as the volume of CO ₂ consumed before the reaction, and CO ₂ is an indispensable raw material in the reaction process and needs to be purchased from the carbon trading market, so the power-to-gas equipment P2G unit electricity consumption The amount of CO ₂ and the cost of purchasing CO ₂ during period t are shown in equations (20) and (21):

In the above formula, ρ _co2 is the density of CO ₂ ; η _p2g is the conversion efficiency of the power-to-gas equipment P2G; P _t,p2g is the electric energy consumed by the power-to-gas equipment P2G during the period t, t=1,2,3..., T is the number of time slots in the IES scheduling cycle of the integrated energy system; L _CH4 is the combustion calorific value of methane, which is 36MJ/m ³ ; f _co2 is the price coefficient for purchasing CO ₂ ; Step 202), the cost of establishing P2G equipment to participate in the carbon trading market is shown in formula (22): f _p2g ＝f _co2 (-M _p2g -M _p )P _t,p2g formula (22) In formula (22), M _p is the carbon emission amount of P2G equipment per unit of electric energy, and the value is 0 because there is no carbon emission during the operation of the equipment; In the step 30), the power-to-gas equipment P2G operation mechanism and carbon trading model established in step 20) are added to the integrated energy system operation optimization model established in step 10) to establish a low-carbon economy with the goal of maximum profit The scheduling model is shown in formula (23):

In formula (23), T is the number of time slots in the IES scheduling period of the integrated energy system; F _t,gas is the fuel purchase cost of the IES in the t period; F _t,grid is the interaction cost between the IES and the external power grid in the t period; F _t,ess is the operating cost of the energy storage device ESS in the integrated energy system IES in the period t; F _t,om is the operation and maintenance cost of each equipment in the integrated energy system IES in the period t; F _t,ct is the cost of the IES in the integrated energy system in the period t Participate in carbon trading fees.

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