Modeling method of low-carbon optimal scheduling model for multi-energy system based on combined operation of p2g and oxy-combustion power plant

Abstract

The modeling method of the low-carbon optimal scheduling model of the multi-energy system based on the combined operation of P2G and oxygen-enriched combustion power plants comprises the following steps: Step 1: establishing a combined operation model of P2G and oxygen-enriched combustion power plants, and using the oxygen generated in the hydrogen production of P2G for the combined operation of oxygen-enriched combustion power plants; Step 2: establishing an energy relationship model of the combined operation of P2G and oxygen-enriched combustion power plants; Step 3: comprehensively considering the system power generation cost, gas purchase cost, operation and maintenance cost, carbon trading cost and carbon sequestration cost, and establishing a low-carbon optimal scheduling model of the multi-energy system based on the combined operation of P2G and oxygen-enriched combustion power plants with the minimum system daily operation cost as the objective function. The method uses the oxygen-enriched combustion technology with high capture efficiency and low capture cost, and combines it with the P2G technology, which not only realizes the full utilization of the oxygen generated in the P2G process, improves the economy of the system, but also reduces the carbon emissions of the multi-energy system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-carbon multi-energy system optimal operation, and relates to a multi-energy system low-carbon optimal scheduling modeling method based on combined operation of P2G and oxygen-rich combustion power plants. BACKGROUND

[0002] The emergence of power-to-gas (P2G) provides technical support for the low-carbon potential of multi-energy systems. P2G can convert excess electricity into natural gas for storage or use, providing a new way for renewable energy consumption. Therefore, how to achieve optimal utilization of P2G, reduce carbon emissions of multi-energy systems, and improve the economy of multi-energy systems is an important problem to be studied.

[0003] In the prior art documents: document [1] "Thermal-electric optimal scheduling of regional integrated energy system with power-to-gas" (Cui Yang, Yan Shi, Zhong Wuzhi, etc. Thermal-electric optimal scheduling of regional integrated energy system with power-to-gas [J]. Power System Technology, 2020, 44(11): 4254-4264.) detailed the P2G process, constructed a two-stage operation model of P2G, and introduced hydrogen fuel cells in the system to realize the mutual coupling of electricity, hydrogen and natural gas, improve the utilization efficiency of P2G, and reduce the loss in the energy conversion process. Document [2] "Low-carbon economic scheduling of P2G integrated energy system considering comprehensive flexible operation mode of carbon capture power plant" (Wang Yijun, Li Menghan, Qi Yan. Low-carbon economic scheduling of P2G integrated energy system considering comprehensive flexible operation mode of carbon capture power plant [J / OL]. Electric Power Automation Equipment: 1-12 [2022-08-01].) proposed a combined operation mode of P2G-carbon capture power plant with liquid storage tank, which realizes time shift of energy and reduces P2G operation cost. Document [3] "Optimal scheduling of interconnected power systems considering carbon capture and power-to-gas coordination" (Chen Boda, Lin Kaide, Zhang Yongjun, etc. Optimal scheduling of interconnected power systems considering carbon capture and power-to-gas coordination [J]. Southern Power Grid Technology, 2019, 13(11): 9-17.) solved the problem of time and space asynchronization in carbon capture and utilization by adding CO2 storage device.

[0004] However, most of the above documents focus on the utilization of hydrogen produced in the P2G process, and few mention the treatment of oxygen produced in the power-to-gas process. Moreover, the coupling with P2G is the high-cost post-combustion capture technology, which will produce high carbon capture cost. SUMMARY

[0005] In view of the above, the present application proposes a multi-energy system low-carbon optimization scheduling model modeling method based on the combined operation of P2G and oxygen-enriched combustion power plants. The model established by the method uses oxygen-enriched combustion technology with high capture efficiency and low capture cost, and combines it with P2G technology. Not only is the oxygen generated in the P2G process fully utilized, improving the economy of the system, but also reducing the carbon emissions and operating costs of the multi-energy system.

[0006] The technical scheme adopted by the present application is:

[0007] The multi-energy system low-carbon optimization scheduling model modeling method based on the combined operation of P2G and oxygen-enriched combustion power plants comprises the following steps:

[0008] Step 1: Establish a P2G and oxygen-enriched combustion power plant combined operation model, and use the oxygen generated in the hydrogen production of P2G for the combined operation of the oxygen-enriched combustion power plant;

[0009] Step 2: Establish an energy relationship model for the combined operation of P2G and oxygen-enriched combustion power plants;

[0010] Step 3: Considering the system generation cost, gas purchase cost, operation and maintenance cost, carbon trading cost and carbon sequestration cost, a multi-energy system low-carbon optimization scheduling model based on the combined operation of P2G and oxygen-enriched combustion power plants is established, with the minimum system daily operation cost as the objective function.

[0011] In step 1, the P2G and oxygen-enriched combustion power plant combined operation model is constructed, and the operation mechanism is as follows:

[0012] The oxygen generated by the first stage of water electrolysis reaction of P2G is input into the boiler of the oxygen-enriched combustion power plant, so that the pulverized coal is fully burned in the oxygen-enriched environment to obtain high-concentration CO2 flue gas; the CO2 flue gas is subjected to dust removal, desulfurization and condensation treatment, and then enters the carbon capture device to capture CO2; the captured CO2 is divided into two parts, one part of CO2 is used as raw material for methanation reaction together with hydrogen generated by water electrolysis, and the remaining CO2 is sequestered by carbon sequestration technology to reduce the emission amount of CO2.

[0013] In step 2, the combined operation model is established by replacing the air separation oxygen device with P2G, wherein the oxygen required by the oxygen-enriched combustion power plant is obtained by P2G, so that the total power generation power of the oxygen-enriched combustion power plant is the sum of the power consumption of the carbon capture device and the power used by the load, and the energy relationship is:

[0014] P G =P C +P N

[0015] In the formula, P G is the total power generation power of the oxygen-enriched combustion power plant; PC P is the power consumed by the carbon capture device; N P is the power consumed by the carbon capture device;

[0016] P is the power consumed by the carbon capture device; N P is the power consumed by the carbon capture device; EL P is the power consumed by the carbon capture device;

[0017]

[0018] P is the power consumed by the carbon capture device; EL P is the power consumed by the carbon capture device; EL P is the power consumed by the carbon capture device; P is the power consumed by the carbon capture device; P is the power consumed by the carbon capture device; C P is the power consumed by the carbon capture device; C P is the power consumed by the carbon capture device; G P is the power consumed by the carbon capture device;

[0019] In the step 3, the objective function expression of the multi-energy system low-carbon optimal scheduling model is:

[0020] min F = F G + F gas + F CS + F ct + F op

[0021] Wherein:

[0022]

[0023]

[0024]

[0025] Q CS,t = Q C,t - Q P2G,t

[0026] F ct = J ct (Q Z - Q CS - Q f )

[0027]

[0028] Where, F is the total cost of system operation; F G is the power generation cost of the oxyfuel combustion power plant; F gas Cost of natural gas consumed by the system; F CS is the carbon sequestration cost; F ct is the carbon trading cost; F op The operation and maintenance cost of each device in the system;

[0029] a is the fuel cost quadratic coefficient of the oxy-fuel combustion power plant, a=0.0014; b is the fuel cost linear coefficient of the oxy-fuel combustion power plant, b=200; c is the fuel cost constant coefficient of the oxy-fuel combustion power plant, c=75; P G,t is the output of the oxyfuel combustion power plant at time t;

[0030] J gas is the gas purchase price; V GT,t 、V GB,t are the natural gas consumption of gas turbine and gas boiler at time t respectively; T represents the total scheduling time, which is 24 hours;

[0031] J CS is the price of CO2 storage unit; Q CS,t is the CO2 storage capacity at time t; Q P2G,t is the CO2 consumption of the P2G process at time t; J ct is the carbon trading price; Q Z Total carbon emissions; Q f is the carbon emission quota; f i P is the operation and maintenance cost per unit output of the i-th type of equipment; i,t is the output of the i-th type of equipment at time t.

[0032] The constraint expression of the multi-energy system low-carbon optimization scheduling model is:

[0033] 1) Electric power balance constraints:

[0034]

[0035] Where, P N,t is the net power generation of the oxygen-enriched combustion power plant at time t; P PV,t is the photovoltaic power generation power at time t; P WT,t P is the wind turbine power generation at time t; GT,t is the power generation of the gas turbine at time t; is the discharge power of the energy storage at time t; P EHP,t P is the electric power consumed by the electric heat pump at time t; EC,t P is the electric power consumed by the electric refrigerator at time t; load,t P is the electric power consumed by the electric load at time t; EL,tis the electric power consumed by the electrolyzer at time t; is the charging power of the electric energy storage at time t.

[0036] 2) Heat balance constraints:

[0037]

[0038] where H EHP,t is the heat power output by the heat pump at time t; is the heat power released by the thermal energy storage at time t; H GT,t is the heat power provided by the gas turbine at time t; is the heat power absorbed by the thermal energy storage at time t; H load,t is the heat power consumed by the thermal load at time t; H AC,t is the heat power consumed by the absorption chiller at time t.

[0039] 3) Cold balance constraints:

[0040] C EC,t +C AC,t =C load,t

[0041] where C EC,t is the refrigeration power of the electric chiller at time t; C AC,t is the cold power output by the absorption chiller at time t; C load,t is the cold power consumed by the cold load at time t.

[0042] 4) Natural gas balance constraints:

[0043] V S,t +V P2G,t =V GT,t +V GB,t +V load,t

[0044] where V S,t is the gas production of the gas source at time t; V P2G,t is the gas production of the P2G device at time t; V GT,t is the gas consumption of the gas turbine at time t; V GB,t is the gas consumption of the gas boiler at time t; V load,t is the natural gas load at time t.

[0045] The present application is a kind of based on P2G and oxygen-enriched combustion power plant combined operation multi-energy system low carbon optimization scheduling model modeling method, technical effects are as follows:

[0046] 1) Current research on P2G mostly focuses on the utilization of hydrogen generated in the P2G process, and there is little mention of the treatment of oxygen generated in the electric-to-gas process. Unlike traditional oxygen-enriched combustion power plants that require air separation oxygen generators to produce oxygen, the present invention supplies the byproduct oxygen generated in the water electrolysis stage of the P2G process to the oxygen-enriched combustion power plant, thus effectively reducing the operating cost of the entire system when the P2G of the present invention is combined with the oxygen-enriched combustion power plant.

[0047] 2) The present invention supplies the oxygen generated in the water electrolysis stage of the P2G process to the oxygen-enriched combustion power plant, so the oxygen consumption of the oxygen-enriched combustion power plant is equal to the oxygen production of the water electrolysis device, i.e.: P2G O G , where O P2G is the oxygen consumption of the oxygen-enriched combustion power plant, and O G is the oxygen production of the water electrolysis device. Based on the above formula, the energy relationship between the power consumption of the water electrolysis and step 2 is derived, which is one of the innovation points of the present invention.

[0048] 3) Unlike traditional oxygen-enriched combustion power plants that require air separation oxygen generators to produce oxygen, the present invention establishes a new multi-energy system low-carbon optimal scheduling model, in which the operating and maintenance costs of the devices in the system F op do not include the operating and maintenance costs of the air separation oxygen generator. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is the modeling method flow chart of the multi-energy system low-carbon optimal scheduling model based on the combined operation of P2G and oxygen-enriched combustion power plant of the present invention.

[0050] Figure 2 is the principle diagram of the combined operation of P2G and oxygen-enriched combustion power plant.

[0051] Figure 3 is the output result diagram of the oxygen-enriched combustion power plant.

[0052] Figure 4 is the comparison diagram of the net carbon emissions of the system under 3 scenarios. DETAILED DESCRIPTION

[0053] The modeling method of the multi-energy system low-carbon optimal scheduling model based on the combined operation of P2G and oxygen-enriched combustion power plant includes the following steps:

[0054] Step 1: Establish a P2G and oxygen-enriched combustion power plant combined operation model, use the oxygen generated in the hydrogen production of P2G for the combined operation of oxygen-enriched combustion power plant;

[0055] Step 2: establish the energy relationship model of P2G and oxygen-enriched combustion power plant combined operation;

[0056] Step 3: considering the system generation cost, gas purchase cost, operation and maintenance cost, carbon trading cost and carbon sequestration cost, a multi-energy system low-carbon optimization scheduling model based on P2G and oxygen-enriched combustion power plant combined operation is established, with the minimum system daily operation cost as the objective function.

[0057] The application will be further described in detail in combination with specific embodiments and drawings.

[0058] Figure 1 The application is based on the multi-energy system low-carbon optimization scheduling model of P2G and oxygen-enriched combustion power plant combined operation. In the application, firstly, the P2G and oxygen-enriched combustion power plant combined operation mechanism is explained, and the mathematical models of P2G and oxygen-enriched combustion power plant are established. Secondly, considering the system generation cost, gas purchase cost, operation and maintenance cost, carbon trading cost and carbon sequestration cost, a multi-energy system low-carbon optimization scheduling model based on P2G and oxygen-enriched combustion power plant combined operation is established, with the minimum system daily operation cost as the objective function.

[0059] Figure 2 It is a P2G and oxygen-enriched combustion power plant combined operation principle diagram. The application considers that P2G technology can produce oxygen while producing hydrogen, and the combined operation of P2G and oxygen-enriched combustion power plant can reduce the operation cost of the system, and the working principle is as follows:

[0060] The oxygen generated by the first stage of P2G water electrolysis reaction is input into the boiler, so that the pulverized coal is fully combusted in the oxygen-enriched environment to obtain high-concentration CO2 flue gas. After dust removal, desulfurization and condensation treatment, the flue gas enters the carbon capture device to realize CO2 capture. The captured CO2 is divided into two parts, one part of CO2 and hydrogen produced by water electrolysis are used as raw materials for methanation reaction, and the remaining CO2 is sequestered by carbon sequestration technology to reduce the emission amount of CO2.

[0061] Table 1 Cost comparison under three scenarios

[0062]

[0063] The application adopts the cold, heat and power load data of a typical day in a certain region for example simulation analysis, sets the total scheduling time as 24 hours, the unit scheduling time as 1h, considers the low-carbon scheduling cost of the system under three scenarios, which are respectively:

[0064] Scenario 1: the oxygen-enriched combustion power plant participates in operation, and the use of P2G equipment is not considered;

[0065] Scenario 2: the oxygen-enriched combustion power plant and P2G equipment are independently operated;

[0066] Scenario 3: Oxygen-enriched combustion power plant combined with P2G, i.e. the low-carbon operation model proposed in this paper.

[0067] As shown in Table 1, the total cost of the system in scenario 3 is the lowest among the three scenarios. The total cost of the system in scenario 2 is reduced by 29.9% and the net carbon emission is reduced by 17% after introducing P2G equipment based on the operation of oxygen-enriched combustion power plant. The gas purchase cost and carbon sequestration cost also decrease significantly. This is because the P2G equipment in the system can convert the captured CO2 into natural gas, which can reduce the carbon sequestration cost on the one hand, and the converted natural gas is used by the system to reduce the gas purchase cost on the other hand. Scenario 3 further considers the combined operation of oxygen-enriched combustion power plant and P2G equipment based on scenario 2, which reduces the total cost of the system in scenario 3 by 9.86% compared with scenario 2, and reduces the net carbon emission by 13.3%. This is due to the fact that P2G equipment supplies oxygen to oxygen-enriched combustion power plant, saving the cost of air separation oxygen generator, and the hydrogen and oxygen resources produced by P2G equipment are fully utilized. This proves the effectiveness of the oxygen-enriched combustion power plant combined with P2G in terms of low carbon and economy.

[0068] Figure 3 is the power output of oxygen-enriched combustion power plant, which is calculated by Figure 3 As can be seen, the power output of oxygen-enriched combustion power plant in scenario 1 is maintained at a high level compared with scenarios 2 and 3. The reason is that scenario 1 does not set P2G equipment. The P2G equipment in scenarios 2 and 3 can convert the CO2 generated by the power plant into natural gas for the gas turbine, thereby reducing the power output of the power plant. Scenario 1 lacks P2G equipment, so the power plant maintains a high power output in order to reduce the gas purchase cost.

[0069] Figure 4 is the net carbon emission of the system in the three scenarios, which is calculated by Figure 4 As can be seen, the net carbon emission of scenario 1 is higher than that of scenarios 2 and 3. The reason is that compared with scenarios 2 and 3, scenario 1 does not have P2G equipment, which fails to realize the recycling of CO2, so its carbon emission is higher. The carbon emission of scenario 3 is generally lower than that of scenario 2, but it is slightly higher than that of scenario 2 in some time periods. The reason is that from 9:00 to 12:00, the power load increases and the wind power output decreases, so the system increases the power supply to the load by appropriately reducing the energy consumption of the carbon capture device, thereby increasing the carbon emission.

Claims

1. A modeling method of a low-carbon optimal scheduling model of a multi-energy system based on combined operation of P2G and an oxygen-enriched combustion power plant, characterized in that The method comprises the following steps: Step 1: establishing a P2G and oxygen-enriched combustion power plant combined operation model, using the oxygen generated by P2G in hydrogen production for the combined operation of the oxygen-enriched combustion power plant; Step 2: establishing an energy relationship model of the P2G and oxygen-enriched combustion power plant combined operation; Step 3: establishing a multi-energy system low-carbon optimal scheduling model based on the P2G and oxygen-enriched combustion power plant combined operation with the minimum system daily operation cost as an objective function; In the step 2, the energy relationship model of the P2G and oxygen-enriched combustion power plant combined operation is established: ； wherein Ptot is the total power generated by the oxy-combustion power plant; Pcc is the power consumed by the carbon capture device; Pload is the power used for the load; ； wherein is the conversion efficiency of the electrolyzer to electrical conversion of hydrogen; is the electrical power consumed by the electrolyzer to electrolyze water; is the heating value of hydrogen; is the density of hydrogen; is the amount of oxygen consumed by an oxy-combustion power plant to produce a unit of power when operating in oxy-combustion conditions; is the power consumed by a carbon capture device to capture a unit of CO2; is the carbon capture efficiency of a carbon capture device; is the unit carbon emission intensity of an oxy-combustion power plant; In the step 3, the multi-energy system low-carbon optimal scheduling model, and an expression of an objective function thereof is: ； Wherein: ； ； ； ； ； ； wherein F is the total cost of system operation; is the power generation cost of the oxy-combustion power plant; is the cost of natural gas consumed by the system; is the cost of carbon sequestration; is the cost of carbon trading; is the operation and maintenance cost of each device in the system; a a quadratic coefficient of fuel cost for an oxycombustion power plant; b a linear coefficient of fuel cost for an oxycombustion power plant; c a constant coefficient of fuel cost for an oxycombustion power plant; a constant coefficient of fuel cost for an oxycombustion power plant; t a power output of the oxycombustion power plant at the time instant is the purchase price of natural gas; , are respectively t the natural gas consumption of the gas turbine, gas boiler at time t; denotes the total scheduling time; is t the gas production of the P2G plant at time t; is the price of CO2 stored per unit; for t CO2 storage amount at the moment; for t CO2 consumption of the P2G process at the moment; is the carbon trading price; Total carbon emissions; for carbon emission quotas; For the i Operation and maintenance costs per unit output of such equipment; For the i Class equipment in t The effort of the moment.

2. The method according to claim 1, wherein the method is characterized in that: In the step 1, the P2G and oxygen-enriched combustion power plant combined operation model is constructed, and an operation mechanism thereof is as follows: The oxygen generated by the first-stage water electrolysis reaction of P2G is input into the boiler of the oxygen-enriched combustion power plant, so that the pulverized coal is fully combusted in the oxygen-enriched environment to obtain high-concentration CO2 flue gas; the CO2 flue gas is subjected to dust removal, desulfurization and condensation treatment, and then is input into a carbon capture device to realize the capture of CO2; the captured CO2 is divided into two parts, one part of the CO2 is used as a raw material of a methanation reaction together with hydrogen generated by water electrolysis, and the remaining CO2 is stored by a carbon storage technology to reduce the emission amount of CO2.

3. The method according to claim 1, wherein the method is characterized in that: The multi-energy system low-carbon optimal scheduling model, and an expression of a constraint condition thereof is: 1) an electric power balance constraint: ； Where, for t Net power generation of the oxy-fuel combustion power plant at any given moment; for t Photovoltaic power generation at any moment; for t Wind turbine power generation at any moment; for t The power generation capacity of the gas turbine at any moment; for t The discharge power of the stored energy at any moment; for t The electric power consumed by the electric heat pump at any moment; for t The electrical power consumed by the refrigerator at each moment; for t The electric power consumed by the electric load at any moment; for t The electrical power consumed by the electrolytic cell at any moment; for t The charging power of the energy storage at all times; 2) a heat balance constraint: ； wherein is t the thermal power output by the electric heat pump at the time instant t; is t the thermal power released by the thermal storage device at the time instant t; is t the thermal power provided by the gas turbine at the time instant t; is t the thermal power absorbed by the thermal storage device at the time instant t; is t the thermal power consumed by the thermal load at the time instant t; is t the thermal power consumed by the absorption chiller at the time instant t; 3) a cold balance constraint: ； wherein is t the refrigeration power of the absorption chiller at the time instant t; is t the cold power output by the absorption chiller at the time instant t; is t the cold power consumed by the cold load at the time instant t; 4) a natural gas balance constraint: ； wherein is t the gas production of the gas source at the moment; is t the gas consumption of the gas turbine at the moment; is t the gas consumption of the gas boiler at the moment; is t the natural gas load at the moment.

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