Energy and carbon emission cooperative operation method for multi-energy coupling sewage treatment plant

Abstract

The invention provides an energy and carbon emission cooperative operation method for a multi-energy coupling sewage treatment plant. The method comprises the following steps: 1) constructing an objective function of an energy and carbon emission cooperative operation model of the multi-energy coupling sewage treatment plant; 2) constructing a water pump constraint, an air blower constraint, a biogas digester and biogas generator constraint, an adjusting tank, a second-stage water tank and a third-stage water tank constraint and a sewage classification recycling constraint of the multi-energy coupling sewage treatment plant energy and carbon emission cooperative operation model; 3) constructing electricity, water, heat and gas balance constraints of the energy and carbon emission collaborative operation model of the multi-energy coupling sewage treatment plant; and 4) solving the energy and carbon emission collaborative operation model of the multi-energy coupling sewage treatment plant to obtain an energy and carbon emission collaborative operation decision of the sewage treatment plant.

Description

Technical Field

[0001] This application relates to the technical field of energy conservation and emission reduction in sewage treatment plants, and particularly to a collaborative operation method for energy and carbon emissions in a multi-energy coupled sewage treatment plant. Background Technique

[0002] Currently, sewage treatment plants generally have prominent problems such as high energy consumption, high carbon emissions, and high operating costs. Moreover, energy consumption and greenhouse gas emissions during the sewage treatment process are one of the important pollution sources in the field of environmental governance. Against the backdrop of increasingly severe climate change and resource shortages, the sewage treatment industry urgently needs to transform towards low-carbon and resource-based directions. Traditional single-objective optimization methods are difficult to meet the collaborative requirements of "energy conservation, carbon reduction, and efficiency improvement". Therefore, there is an urgent need to establish a collaborative operation method for energy and carbon emissions in a multi-energy coupled sewage treatment plant to achieve the optimal operation of the sewage treatment plant.

[0003] The multi-energy coupled sewage treatment system is an important development direction for the future sewage treatment industry. During the operation process, the optimization of blower start-stop, the temperature control of biogas digesters, and the reasonable configuration of sewage grading treatment and recycling technologies are crucial for the low-carbon economic operation of sewage treatment plants. Existing sewage treatment scheduling methods usually only optimize for a single objective, such as energy consumption or water quality. Although they can reduce some operating costs, it is difficult to take into account carbon emission control and resource recovery, thus unable to achieve the overall low-carbon and efficient operation of the system. If the carbon emissions, blower start-stop, biogas digester temperature control, and sewage grading recovery and utilization and other scheduling elements during the sewage treatment process can be synergistically optimized, a collaborative operation model for energy and carbon emissions in a multi-energy coupled sewage treatment plant can be constructed to fully exploit the low-carbon potential of the sewage treatment plant and achieve multiple benefits of economy, environment, and resources. Summary of the Invention

[0004] Object of the Invention. Based on this, it is necessary to provide a collaborative operation method for energy and carbon emissions in a multi-energy coupled sewage treatment plant in view of the above problems.

[0005] Technical Solution. To solve the above technical problems, the present invention proposes a collaborative operation method for energy and carbon emissions in a multi-energy coupled sewage treatment plant, and the method includes the following steps:

[0006] Step 1, construct the objective function of the collaborative operation model for energy and carbon emissions in a multi-energy coupled sewage treatment plant;

[0007] Step 2, construct the constraints of water pumps, blowers, biogas digesters, biogas generators, regulating ponds, secondary ponds, tertiary ponds, and sewage grading recovery and utilization for the collaborative operation model of energy and carbon emissions in a multi-energy coupled sewage treatment plant;

[0008] Step 3, construct the electricity, water, heat, and gas balance constraints of the collaborative operation model for energy and carbon emissions in a multi-energy coupled sewage treatment plant;

[0009] Step 4: Solve the energy and carbon emission collaborative operation model of the multi-energy coupled sewage treatment plant to obtain the energy and carbon emission collaborative operation decision of the sewage treatment plant.

[0010] Furthermore, in step (1), the objective function for constructing the energy and carbon emission collaborative operation model of the multi-energy coupled sewage treatment plant is expressed as follows:

[0011]

[0012] In the formula, T is the number of scheduling period time segments; t is the operation time segment; is the electricity purchase price at time segment t; P t E,buy is the electricity purchase power at time segment t; is the electricity selling price at time segment t; P t E,sell is the electricity selling power at time segment t; is the gas purchase price at time segment t; is the gas purchase volume at time segment t; is the gas selling price at time segment t; is the gas selling volume at time segment t; k BES is the operation and maintenance cost coefficient of the battery; P t BES,ch is the charging power of the battery at time segment t; P t BES,dis is the discharging power of the battery at time segment t; k HES is the operation and maintenance cost coefficient of the heat storage tank; is the heat storage power of the heat storage tank at time segment t; is the heat release power of the heat storage tank at time segment t; k EB is the operation and maintenance cost coefficient of the electric boiler; P t EB is the power consumption of the electric boiler at time segment t; k BG is the operation and maintenance cost coefficient of the biogas engine; P t BG is the power consumption of the biogas engine at time segment t; k LP is the operation and maintenance cost coefficient of the lift pump; P t LP is the power consumption of the lift pump at time segment t; k RP is the operation and maintenance cost coefficient of the reflux pump; P t RP is the power consumption of the reflux pump at time segment t; k air is the operation and maintenance cost coefficient of the blower; P t air is the power consumption of the blower at time segment t; k TP is the operation and maintenance cost coefficient of the third-level equipment; P tTP is the power consumption of the third - level equipment in period t; k PV is the operation and maintenance cost coefficient of the photovoltaic unit; P t PV is the power generation of the photovoltaic unit in period t; is the carbon emission penalty coefficient; is the carbon emission of the blower in period t; is the carbon emission of the biogas engine in period t; is the reference emission in period t; is the selling price per unit volume of the secondary - treated water in period t; is the effluent flow rate of the secondary - level water tank in period t; is the selling price per unit volume of the tertiary - treated water in period t; is the effluent flow rate of the tertiary - level water tank in period t; is the discharge water flow rate of the secondary - treated water in period t; k 3,en is the environmental protection benefit coefficient of the tertiary - treated water; is the discharge water flow rate of the tertiary - treated water in period t; k EB,BON is the environmental protection benefit coefficient corresponding to the removal of BOD substances; is the BOD concentration of the influent of the sewage treatment plant in period t; is the BOD concentration of the effluent of the aeration tank in period t; k EB,TKN is the environmental protection benefit coefficient corresponding to the removal of TKN substances; is the TKN concentration of the influent of the sewage treatment plant in period t; is the TKN concentration of the effluent of the aeration tank in period t.

[0013] Furthermore, the specific process of step (2) is as follows:

[0014] (201) Establish the pump constraint:

[0015]

[0016] In the formula, is the head of the lift pump in period t; κ LP,1 is the hydraulic characteristic coefficient of the lift pump; η LP is the efficiency of the lift pump; δ LP is the specific gravity of the sewage flowing through the lift pump; is the sewage flow rate of the lift pump in period t; κ LP,2 is the hydraulic characteristic coefficient of the lift pump; is the relative rotational speed of the lift pump in period t; κ LP,3 is the hydraulic characteristic coefficient of the lift pump; is the head of the reflux pump in period t; δ RP,1 is the hydraulic characteristic coefficient of the reflux pump; η RP is the efficiency of the reflux pump; δRP is the specific gravity of the sewage flowing through the reflux pump; is the sewage flow rate of the reflux pump at time t; δ RP,2 is the hydraulic characteristic coefficient of the reflux pump; is the relative rotational speed of the reflux pump at time t; δ RP,3 is the hydraulic characteristic coefficient of the reflux pump;

[0017] (202) Establish the blower constraint:

[0018]

[0019]

[0020] Where: is the oxygen demand of the aeration tank at time t; is the air gas constant; T in is the inlet temperature of the blower; T ref is the reference temperature of the aeration tank; is at the reference temperature T ref the oxygen saturation concentration of tap water below; β is the proportionality coefficient of the dissolved oxygen concentration in sewage and tap water; T′ is the temperature of the aeration tank; C s,T is the oxygen saturation concentration of tap water at temperature T′; C W is the concentration of dissolved oxygen in sewage; M a is the relative molecular mass of air; K L is the oxygen transfer efficiency under standard environmental conditions; is the mass of oxygen contained in unit mass of air; v is the isotropic correction coefficient of air; η B is the mechanical efficiency of the blower; α is the ratio of the oxygen transfer rate in sewage and tap water at temperature T′; θ is the Arrhenius constant; is the static pressure at the outlet of the diffuser at time t; p AP is the atmospheric pressure; k DP is the diffuser pressure coefficient; A d is the cross-sectional area of the diffuser; is the sewage flow rate of the secondary treatment link at time t; is the oxygen demand for oxidation in the aeration tank at time t; is the nitrification oxygen demand in the aeration tank at time t; q SP,min is the lower limit of the sewage flow rate of the secondary treatment link at time t; is the 0-1 variable of the blower operation state at time t, taking 1 means running; q SP,max is the upper limit of the sewage flow rate of the secondary treatment link at time t; is the 0-1 variable of the change in the blower operation state at time t, taking 1 means the blower is put into operation from the shutdown state; A 0-1 variable for the operating state change of the blower in period t. Taking 1 indicates that the blower changes from the operating state to the shutdown state; t-1 is the previous operating period. A 0-1 variable for the operating state of the blower in period t-1. Taking 1 indicates operation; τ is an operating period of the blower; τ-1 is the previous operating period of the blower in period τ; τ+1 is the next operating period of the blower in period τ. A 0-1 variable for the use of secondary treated water in period t. Taking 1 indicates irrigation, and taking 0 indicates discharge or entry into tertiary treatment.

[0021] (203) Establish the constraints for the biogas digester and biogas generator:

[0022]

[0023] In the formula, The biogas production of the biogas digester in period t; ξ F The sludge coefficient after sewage standing and sedimentation; T I The reference fermentation temperature of the biogas digester; The sludge biogas production coefficient corresponding to the reference fermentation temperature T I α is the fitting coefficient; T t F The fermentation temperature of the biogas digester in period t; γ is the fitting coefficient; The biogas consumption of the biogas engine in period t; L B The calorific value of biogas; η G The biogas power generation efficiency; The heat release power of the biogas digester in period t; ρ SL The sludge density; c SL The specific heat capacity; T t S,I The inlet sludge temperature of the biogas digester in period t; κ a The air heat transfer coefficient; A s The side area of the biogas digester; T t A The air temperature in period t; κ g The soil heat transfer coefficient; A b The bottom area of the biogas digester; T t S The soil temperature in period t;

[0024] (204) Establish the constraints for the regulating tank, secondary tank, and tertiary tank:

[0025]

[0026] In the formula, The inlet flow rate of the water tank in period t; The inlet flow rate of the regulating tank in period t; is the influent flow rate of the secondary water tank during period t; is the influent flow rate of the tertiary water tank during period t; is the effluent flow rate of the water tank during period t; is the effluent flow rate of the regulation tank during period t; is the discharge flow rate of the water tank during period t; W t P is the water volume of the water tank during period t; is the water volume of the water tank at period t - 1; is the lower limit of the influent flow rate of the water tank during period t; is the upper limit of the influent flow rate of the water tank during period t: is the lower limit of the effluent flow rate of the water tank during period t; is the upper limit of the effluent flow rate of the water tank during period t; is the lower limit of the discharge flow rate of the water tank during period t; is the upper limit of the discharge flow rate of the water tank during period t;

[0027] (205) Establish the constraints for hierarchical sewage recycling and utilization:

[0028]

[0029] In the formula, is the lower limit of the BOD concentration of irrigation water during period t; is the upper limit of the BOD concentration of irrigation water during period t; is the upper limit of the BOD concentration of the secondary effluent during period t.

[0030] Furthermore, the specific process of step (3) is as follows:

[0031] (301) Establish the power balance constraint:

[0032] P t BG +P t E,buy +P t BES,dis +P t PV =P t E,sell +P t EB +P t BES,ch +P t air +P t TP +P t LP +P t RP (22)

[0033] (302) Establish the water balance constraint:

[0034]

[0035] In the formula, ω 1 is the water flow loss coefficient of the primary treatment process; is the raw sewage flow entering the sewage treatment plant at time t; ω 2 is the water flow loss coefficient of the primary treatment process; ω 3 is the water flow loss coefficient of the secondary treatment process; ω 4 is the set reflux ratio; ω 5 is the water flow loss coefficient of the secondary treatment process; is the sewage flow of the tertiary treatment process at time t; ω 6 is the water flow loss coefficient of the tertiary treatment process;

[0036] (303) Establish the heat balance constraint:

[0037]

[0038] In the formula: η EB is the heating efficiency of the electric boiler;

[0039] (304) Establish the gas balance constraint:

[0040]

[0041] Furthermore, the specific process of step (4) is as follows: Use the MILP solver on the GAMS platform to solve the energy and carbon emission co - operation operation model of the multi - energy coupled sewage treatment plant to obtain the operation strategy of the sewage treatment plant.

[0042] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0043] The above-mentioned method for the collaborative operation of energy and carbon emissions in a multi-energy coupling sewage treatment plant takes into account the sewage treatment process flow, various equipment, and relevant constraints of water quality control. By introducing a sewage grading treatment and recycling mechanism, considering the carbon emission cost, the start-stop of blowers, and the temperature control means of biogas digesters, a complete collaborative operation model of energy and carbon emissions in a multi-energy coupling sewage treatment plant is constructed, and the model is solved to obtain the collaborative operation decision of energy and carbon emissions in a multi-energy coupling sewage treatment plant. By scheduling the sewage treatment plant, the goal of energy conservation, carbon reduction, and efficiency improvement in the sewage treatment plant is achieved, the utilization rate of renewable energy is increased, the sewage recycling efficiency is improved, and reliable technical support is provided for the green and low-carbon transformation of the sewage treatment industry. The present invention takes into account the sewage treatment process flow, equipment operation constraints, and water quality control requirements, introduces the start-stop of blowers, the temperature control of biogas digesters, and the sewage grading recycling mechanism, improves the energy utilization rate of the sewage treatment plant, reduces the carbon emissions of the sewage treatment plant, and improves the water resource recycling rate, providing a solution for the energy-saving and low-carbon operation of the sewage treatment plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic flow chart of the method for the collaborative operation of energy and carbon emissions in a multi-energy coupling sewage treatment plant;

[0045] Figure 2 It is a schematic structural diagram of a sewage treatment plant;

[0046] Figure 3 It is the power scheduling result of a sewage treatment plant without considering three scheduling factors;

[0047] Figure 4 It is the power scheduling result of a sewage treatment plant considering three scheduling factors. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] In order to make the purpose, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0049] As Figure 1 shown, the present invention proposes a method for the collaborative operation of energy and carbon emissions in a multi-energy coupling sewage treatment plant, and the method includes the following steps:

[0050] Step 1, constructing the objective function of the collaborative operation model of energy and carbon emissions in a multi-energy coupling sewage treatment plant;

[0051] Step 2, constructing the pump constraints, blower constraints, biogas digesters, biogas generators, regulating ponds, secondary ponds, tertiary ponds constraints, and sewage grading recycling constraints of the collaborative operation model of energy and carbon emissions in a multi-energy coupling sewage treatment plant;

[0052] Step 3, construct the electricity, water, heat, and gas balance constraints of the collaborative operation model for energy and carbon emissions in a multi-energy-coupled sewage treatment plant;

[0053] Step 4, solve the collaborative operation model for energy and carbon emissions in a multi-energy-coupled sewage treatment plant to obtain the collaborative operation decision of energy and carbon emissions in the sewage treatment plant.

[0054] Furthermore, in step (1), the objective function of the collaborative operation model for energy and carbon emissions in a multi-energy-coupled sewage treatment plant is constructed as follows:

[0055]

[0056] In the formula, T is the number of scheduling period time segments; t is the operation time segment; is the electricity purchase price at time t; P t E,buy is the electricity purchase power at time t; is the electricity selling price at time t; P t E,sell is the electricity selling power at time t; is the gas purchase price at time t; is the gas purchase volume at time t; is the gas selling price at time t; is the gas selling volume at time t; k BES is the operation and maintenance cost coefficient of the battery; P t BES,ch is the charging power of the battery at time t; P t BES,dis is the discharging power of the battery at time t; k HES is the operation and maintenance cost coefficient of the heat storage tank; is the heat storage power of the heat storage tank at time t; is the heat release power of the heat storage tank at time t; k EB is the operation and maintenance cost coefficient of the electric boiler; P t EB is the power consumption of the electric boiler at time t; k BG is the operation and maintenance cost coefficient of the biogas engine; P t BG is the power consumption of the biogas engine at time t; k LP is the operation and maintenance cost coefficient of the lift pump; P t LP is the power consumption of the lift pump at time t; k RP is the operation and maintenance cost coefficient of the reflux pump; P t RP is the power consumption of the reflux pump at time t; k air is the operation and maintenance cost coefficient of the blower; P t airis the power consumption of the blower during period t; k TP is the operation and maintenance cost coefficient of the third-level equipment; P t TP is the power consumption of the third-level equipment during period t; k PV is the operation and maintenance cost coefficient of the photovoltaic unit; P t PV is the power generation power of the photovoltaic unit during period t; is the carbon emission penalty coefficient; is the carbon emission of the blower during period t; is the carbon emission of the biogas engine during period t; is the reference emission during period t; is the selling price per unit volume of the secondary treated water during period t; is the effluent flow rate of the secondary water tank during period t; is the selling price per unit volume of the tertiary treated water during period t; is the effluent flow rate of the tertiary water tank during period t; is the discharge water flow rate after secondary treatment during period t; k 3,en is the environmental protection benefit coefficient of the tertiary treated water; is the discharge water flow rate after tertiary treatment during period t; k EB,BON is the environmental protection benefit coefficient corresponding to the removal of BOD substances; is the BOD concentration of the influent of the sewage treatment plant during period t; is the BOD concentration of the effluent of the aeration tank during period t; k EB,TKN is the environmental protection benefit coefficient corresponding to the removal of TKN substances; is the TKN concentration of the influent of the sewage treatment plant during period t; is the TKN concentration of the effluent of the aeration tank during period t.

[0057] Furthermore, the specific process of step (2) is as follows:

[0058] (201) Establish the pump constraint:

[0059]

[0060] In the formula, is the head of the lift pump during period t; κ LP,1 is the hydraulic characteristic coefficient of the lift pump; η LP is the efficiency of the lift pump; δ LP is the specific gravity of the sewage flowing through the lift pump; is the sewage flow rate of the lift pump during period t; κ LP,2 is the hydraulic characteristic coefficient of the lift pump; is the relative rotational speed of the lift pump during period t; κ LP,3 is the hydraulic characteristic coefficient of the lift pump; is the head of the reflux pump during period t; δ RP,1 is the hydraulic characteristic coefficient of the reflux pump; η RP is the efficiency of the reflux pump; δ RP is the specific gravity of the sewage flowing through the reflux pump; is the sewage flow rate of the reflux pump during period t; δ RP,2 is the hydraulic characteristic coefficient of the reflux pump; is the relative rotational speed of the reflux pump during period t; δ RP,3 is the hydraulic characteristic coefficient of the reflux pump;

[0061] (202) Establish the blower constraint:

[0062] In the formula: is the oxygen demand of the aeration tank during period t; is the air gas constant; T in is the temperature at the blower inlet; T ref is the reference temperature of the aeration tank; is the oxygen saturation concentration of tap water at the reference temperature T ref Under ; β is the proportionality coefficient of the dissolved oxygen concentration in sewage and tap water; T′ is the temperature of the aeration tank; C s,T is the oxygen saturation concentration of tap water at the temperature T′; C W is the concentration of dissolved oxygen in sewage; M a is the relative molecular mass of air; K L is the oxygen transfer efficiency under standard environmental conditions; is the mass of oxygen contained in unit mass of air; v is the isotropic correction coefficient of air; η B is the mechanical efficiency of the blower; α is the ratio of the oxygen transfer rate in sewage and tap water at the temperature T′; θ is the Arrhenius constant; is the static pressure at the diffuser outlet during period t; p AP is the atmospheric pressure; k DP is the diffuser pressure coefficient; A d is the cross-sectional area of the diffuser; is the sewage flow rate of the secondary treatment link during period t; is the oxygen demand for oxidation in the aeration tank during period t; is the nitrification oxygen demand in the aeration tank during period t; q SP,min is the lower limit of the sewage flow rate of the secondary treatment link during period t; is the 0-1 variable of the blower operating state during period t, taking 1 to indicate operation; q SP,max is the upper limit of the sewage flow rate of the secondary treatment link during period t; is a 0-1 variable representing the change in the operating state of the blower during time period t. Taking 1 means the blower is put into operation from the shutdown state; is a 0-1 variable representing the change in the operating state of the blower during time period t. Taking 1 means the blower changes from the operating state to the shutdown state; t - 1 is the previous operating period; is a 0-1 variable representing the operating state of the blower during time period t - 1. Taking 1 means it is operating; τ is a time period of the blower operation; τ - 1 is the previous operating period of the blower during τ; τ + 1 is the next operating period of the blower during τ; is a 0-1 variable representing the use of secondary treated water during time period t. Taking 1 means irrigation, and taking 0 means discharge or entering the tertiary treatment;

[0063] (203) Establish the constraints for the biogas digester and biogas generator:

[0064]

[0065] In the formula, is the biogas production of the biogas digester during time period t; ξ F is the sludge coefficient after the sewage is statically settled and precipitated; T I is the reference fermentation temperature of the biogas digester; is the reference fermentation temperature T I corresponding sludge biogas production coefficient; α is the fitting coefficient; T t F is the fermentation temperature of the biogas digester during time period t; γ is the fitting coefficient; is the biogas consumption of the biogas engine during time period t; L B is the calorific value of biogas; η G is the biogas power generation efficiency; is the heat release power of the biogas digester during time period t; ρ SL is the sludge density; c SL is the specific heat capacity; T t S,I is the inlet sludge temperature of the biogas digester during time period t; κ a is the air heat transfer coefficient; A s is the side area of the biogas digester; T t A is the air temperature during time period t; κ g is the soil heat transfer coefficient; A b is the bottom area of the biogas digester; T t S is the soil temperature during time period t;

[0066] (204) Establish the constraints for the regulating tank, secondary tank, and tertiary tank:

[0067]

[0068] In the formula, is the water inflow rate of the pool during period t; is the water flow rate of the regulating pool during period t; is the water inlet flow rate of the secondary water tank during period t; is the water inlet flow rate of the third-level water pool during period t; is the outflow rate of the pool during period t; is the outflow rate of the regulating pool during period t; is the water discharge from the pool during period t; W t P is the water volume in the pool during period t; is the water volume in the pool during period t-1; is the lower limit of the water inflow rate of the pool during period t; is the upper limit of the water flow rate of the pool during period t: is the lower limit of the water outflow of the pool during period t; is the upper limit of the water outflow from the pool during period t; is the lower limit of the water discharge from the pool during period t; is the upper limit of the water discharge from the pool during period t;

[0069] (205) Establishing constraints for wastewater recycling and utilization:

[0070]

[0071] In the formula, is the lower limit of BOD concentration of irrigation water during period t; is the upper limit of BOD concentration of irrigation water during period t; It is the upper limit of BOD concentration of secondary discharge water in period t.

[0072] Furthermore, the specific process of step (3) is as follows:

[0073] (301)Establish electrical balance constraints:

[0074] P t BG +P t E,buy +P t BES,dis +P t PV =P t E,sell +P t EB +P t BES,ch +P t air +P t TP +P t LP +P tRP (22)

[0075] (302) Establish the water balance constraint:

[0076]

[0077] where ω 1 is the water flow loss coefficient of the primary treatment process; is the raw sewage flow entering the sewage treatment plant at time t; ω 2 is the water flow loss coefficient of the primary treatment process; ω 3 is the water flow loss coefficient of the secondary treatment process; ω 4 is the set reflux ratio; ω 5 is the water flow loss coefficient of the secondary treatment process; is the sewage flow of the tertiary treatment process at time t; ω 6 is the water flow loss coefficient of the tertiary treatment process;

[0078] (303) Establish the heat balance constraint:

[0079]

[0080] where: η EB is the heating efficiency of the electric boiler;

[0081] (304) Establish the gas balance constraint:

[0082]

[0083] Furthermore, the specific process of step (4) is as follows: Use the MILP solver on the GAMS platform to solve the energy and carbon emission collaborative operation model of the multi-energy coupled sewage treatment plant, and obtain the operation strategy of the sewage treatment plant.

[0084] Take a small urban sewage treatment plant as an example. Adopt the sewage treatment plan for a certain day, and the scheduling time is 24 hours. Use the MILP solver on the GAMS platform to solve the energy and carbon emission collaborative operation model of the multi-energy coupled sewage treatment plant, and obtain the operation strategy of the sewage treatment plant.

[0085] To illustrate the advantages of the proposed energy and carbon emission collaborative operation method for the multi-energy coupled sewage treatment plant, explore the impact on the total cost by adopting the operation plans of the sewage treatment plant with different scheduling elements. The plans are set as follows:

[0086] Plan 1: The sewage treatment plant does not consider carbon emissions, does not consider the start and stop of the blower and the temperature control of the biogas digester, and does not consider the hierarchical recycling of sewage;

[0087] Scenario 2: The sewage treatment plant does not account for carbon emissions, does not consider the start and stop of blowers and the temperature control of biogas digesters, and considers the hierarchical recycling and utilization of sewage;

[0088] Scenario 3: The sewage treatment plant does not account for carbon emissions, considers the start and stop of blowers and the temperature control of biogas digesters, and does not consider the hierarchical recycling and utilization of sewage;

[0089] Scenario 4: The sewage treatment plant considers carbon emissions, does not consider the start and stop of blowers and the temperature control of biogas digesters, and does not consider the hierarchical recycling and utilization of sewage;

[0090] Scenario 5: The sewage treatment plant considers carbon emissions, considers the start and stop of blowers and the temperature control of biogas digesters, and considers the hierarchical recycling and utilization of sewage.

[0091] The scheduling results of different scenarios are shown in Table 1. Negative costs correspond to benefits; the total energy consumption is the sum of the energy consumption of secondary and tertiary water treatment and the energy consumption of pumps. It can be seen from Table 1 that the total costs of the five scenarios are sorted from low to high as 5 < 3 < 2 < 1 < 4, and the carbon emissions are sorted as 5 < 3 < 1 < 2 < 4, indicating that the three scheduling elements considered in the proposed model have obvious advantages in reducing energy consumption, carbon emissions, and operating costs, and also reflect that the three scheduling elements will have different impacts on the scheduling results.

[0092] Table 1 Scheduling results of different scenarios

[0093]

[0094] Figure 3 (Scenario 1), Figure 4 (Scenario 5) are the power scheduling results of the sewage treatment plant without considering / considering the three scheduling factors respectively. As can be seen from the figure, after the sewage treatment plant considers carbon emissions, the start and stop of blowers, the temperature control of biogas digesters, and the hierarchical recycling and utilization of sewage, both scenarios try to use photovoltaic power supply as much as possible and arrange the water treatment tasks during low electricity price periods to make a profit through the difference in the purchase and sale of electricity and the storage and release of energy by batteries. The difference is that Scenario 1 only needs to consider the sewage treatment demand, while Scenario 5 also needs to cooperate with the sewage treatment and reuse work. Therefore, there are obvious differences in the power consumption of the sewage treatment equipment related to the secondary and tertiary treatment links at each time period between the two scenarios; in addition, Scenario 5 can also flexibly start and stop the blowers to reduce the energy consumption of sewage treatment and cooperate with the temperature control to optimize the operation of the biogas digester, so as to reduce the operating cost of the sewage treatment plant.

[0095] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for collaborative operation of energy and carbon emissions in a multi-energy-coupled sewage treatment plant, characterized in that, The method includes the following steps: Step 1, construct the objective function of the collaborative operation model of energy and carbon emissions in a multi-energy-coupled sewage treatment plant; Step 2, construct the constraints of pumps, blowers, biogas digesters, biogas generators, regulating ponds, secondary ponds, tertiary ponds, and the constraint of hierarchical sewage recycling and utilization in the collaborative operation model of energy and carbon emissions in a multi-energy-coupled sewage treatment plant; Step 3, construct the electrical, water, heat, and gas balance constraints in the collaborative operation model of energy and carbon emissions in a multi-energy-coupled sewage treatment plant; Step 4, solve the collaborative operation model of energy and carbon emissions in a multi-energy-coupled sewage treatment plant to obtain the collaborative operation decision of energy and carbon emissions in the sewage treatment plant.

2. A method for collaborative operation of energy and carbon emissions in a multi-energy-coupled sewage treatment plant according to claim 1, characterized in that In step (1), the objective function of the collaborative operation model of energy and carbon emissions in a multi-energy-coupled sewage treatment plant is constructed as follows: In the formula, T is the number of time periods in the scheduling cycle; t is the operating period; P is the electricity purchase price during period t; t E,buy is the power purchased during period t; is the electricity price during period t; P t E,sell is the electricity sold during period t; is the gas purchase price during period t; is the gas purchase volume during period t; is the gas selling price during period t; is the gas sales volume during period t; k BES is the battery operation and maintenance cost coefficient; P t BES ,ch is the charging power of the battery during period t; P t BES,dis is the discharge power of the battery during period t; k HES is the operation and maintenance cost coefficient of the heat storage tank; is the heat storage power of the heat storage tank during period t; is the heat release power of the heat storage tank during period t; k EB is the operation and maintenance cost coefficient of the electric boiler; P t EB is the power consumption of the electric boiler during period t; k BG is the operation and maintenance cost coefficient of the biogas engine; P t BG is the power consumption of the biogas engine during period t; k LP is the operation and maintenance cost coefficient of the lift pump; P t LP k is the power consumption of the boost pump during period t; RP is the operation and maintenance cost coefficient of the reflux pump; P t RP is the power consumption of the reflux pump during period t; k air is the operation and maintenance cost coefficient of the blower; P t air is the power consumption of the blower during period t; k TP is the operation and maintenance cost coefficient of the third-level equipment; P t TP is the power consumption of the third-level equipment during period t; k PV is the operation and maintenance cost coefficient of the photovoltaic unit; P t PV is the power generation power of the photovoltaic unit during period t; is the carbon emission penalty coefficient; is the carbon emission of the blower during period t; is the carbon emission of the biogas engine during period t; is the reference emission during period t; is the selling unit price of the secondary treated water in period t; is the effluent flow rate of the secondary water tank in period t; is the selling unit price of the tertiary treated water in period t; is the effluent flow rate of the tertiary water tank in period t; is the discharge water flow rate after secondary treatment in period t; k 3,en is the environmental protection benefit coefficient of the tertiary treated water; is the discharge water flow rate after tertiary treatment in period t; k EB,BON is the environmental protection benefit coefficient corresponding to the removal of BOD substances; is the BOD concentration of the influent of the sewage treatment plant in period t; is the BOD concentration of the effluent of the aeration tank in period t; k EB,TKN is the environmental protection benefit coefficient corresponding to the removal of TKN substances; is the TKN concentration of the influent of the sewage treatment plant in period t; is the TKN concentration of the effluent of the aeration tank in period t.

3. The method for collaborative operation of energy and carbon emissions in a multi-energy-coupled sewage treatment plant according to claim 1, characterized in that, The specific process of step (2) is as follows: (201) Establish the pump constraint: In the formula, is the head of the lift pump at time t; κ LP,1 is the hydraulic characteristic coefficient of the lift pump; η LP is the efficiency of the lift pump; δ LP is the specific gravity of the sewage flowing through the lift pump; is the sewage flow rate of the lift pump at time t; κ LP,2 is the hydraulic characteristic coefficient of the lift pump; is the relative rotational speed of the lift pump at time t; κ LP,3 is the hydraulic characteristic coefficient of the lift pump; is the head of the reflux pump at time t; δ RP,1 is the hydraulic characteristic coefficient of the reflux pump; η RP is the efficiency of the reflux pump; δ RP is the specific gravity of the sewage flowing through the reflux pump; is the sewage flow rate of the reflux pump at time t; δ RP,2 is the hydraulic characteristic coefficient of the reflux pump; is the relative rotational speed of the reflux pump at time t; δ RP,3 is the hydraulic characteristic coefficient of the reflux pump; (202) Establish the blower constraint: In the formula: is the oxygen demand of the aeration tank in the t period; θ is the air gas constant; T in is the temperature at the inlet of the blower; T ref is the reference temperature of the aeration tank; is the oxygen saturation concentration of tap water at the reference temperature T ref ; β is the proportionality coefficient of the dissolved oxygen concentration in sewage and tap water; T′ is the temperature of the aeration tank; C s,T is the oxygen saturation concentration of tap water at the temperature T′; C W is the concentration of dissolved oxygen in sewage; M a is the relative molecular mass of air; K L is the oxygen transfer efficiency under standard environmental conditions; is the mass of oxygen contained in unit mass of air; v is the air isotropy correction coefficient; η B is the mechanical efficiency of the blower; α is the ratio of the oxygen transfer rate in sewage to that in tap water at temperature T'. θ is the Arrhenius constant; is the static pressure at the diffuser outlet during the t period; p AP is the atmospheric pressure; k DP is the diffuser pressure coefficient; A d is the cross-sectional area of the diffuser; is the sewage flow rate in the secondary treatment process during the t period; is the oxygen demand for oxidation in the aeration tank during the t period; is the nitrification oxygen demand in the aeration tank during the t period; q SP,min is the lower limit of the sewage flow rate in the secondary treatment process during the t period; is a 0-1 variable representing the operating state of the blower during the t period, taking 1 for operating; q SP,max is the upper limit of the sewage flow rate in the secondary treatment process during the t period; is a 0-1 variable representing the change in the operating state of the blower during period t. Taking 1 indicates that the blower is put into operation from the shutdown state; is a 0-1 variable representing the change in the operating state of the blower during period t. Taking 1 indicates that the blower changes from the operating state to the shutdown state; t - 1 is the previous operation period; is a 0 - 1 variable for the operation status of the blower in the t - 1 period, taking 1 to indicate operation; τ is a period of blower operation; τ - 1 is the previous operation period of the blower in the τ period; τ + 1 is the next operation period of the blower in the τ period; is a 0 - 1 variable for the use of secondary treated water in the t period, taking 1 to indicate irrigation and 0 to indicate discharge or entry into tertiary treatment; (203) Establish the constraints of biogas digesters and biogas generators: In the formula, is the amount of biogas produced by the biogas digester in the t period; ξ F is the sludge coefficient after the sewage is statically settled and precipitated; T I is the reference fermentation temperature of the biogas digester; is the sludge biogas production coefficient corresponding to the reference fermentation temperature T I ; α is the fitting coefficient; T t F is the fermentation temperature of the biogas digester in the t period; γ is the fitting coefficient; is the amount of biogas consumed by the biogas engine in the t period; L B is the calorific value of biogas; η G is the biogas power generation efficiency; is the heat release power of the biogas digester in the t period; ρ SL is the sludge density; c SL is the specific heat capacity; T t S,I is the inlet sludge temperature of the biogas digester in the t period; κ a is the air heat transfer coefficient; A s is the side area of the biogas digester; T t A is the air temperature in the t period; κ g is the soil heat transfer coefficient; A b is the bottom area of the biogas digester; T t S is the soil temperature in the t period; (204) Establish the constraints of the regulating pond, secondary pond, and tertiary pond: In the formula, is the water inflow rate of the water tank in the t-th period; is the water inflow rate of the regulating tank in the t-th period; is the water inflow rate of the secondary water tank in the t-th period; is the water inflow rate of the tertiary water tank in the t-th period; is the water outflow rate of the water tank in the t-th period; is the water outflow rate of the regulating tank in the t-th period; is the water discharge rate of the water tank in the t-th period; W t P is the water volume of the water tank in the t-th period; is the water volume of the water tank in the (t - 1)-th period; is the lower limit of the water inflow rate of the water tank in the t-th period; is the upper limit of the water inflow rate of the water tank in the t-th period: is the lower limit of the water outflow rate of the water tank in the t-th period; is the upper limit of the water outflow rate of the water tank in the t-th period; is the lower limit of the water discharge flow rate of the water tank during period t; is the upper limit of the water discharge flow rate of the water tank during period t; (205) Establish the constraint of hierarchical sewage recycling and utilization: In the formula, is the lower limit of the BOD concentration of irrigation water in period t; is the upper limit of the BOD concentration of irrigation water in period t; is the upper limit of the BOD concentration of secondary effluent in period t.

4. A method for coordinated operation of energy and carbon emissions in a multi-energy coupled sewage treatment plant according to claim 1, characterized in that, The specific process of step (3) is as follows: (301) Establish the electrical balance constraint: (302) Establish the water balance constraint: where ω 1 is the water flow loss coefficient of the primary treatment stage; is the raw sewage flow entering the sewage treatment plant at time t; ω 2 is the water flow loss coefficient of the primary treatment stage; ω 3 is the water flow loss coefficient of the secondary treatment stage; ω 4 is the set reflux ratio; ω 5 is the water flow loss coefficient of the secondary treatment stage; is the sewage flow of the tertiary treatment stage at time t; ω 6 is the water flow loss coefficient of the tertiary treatment stage; (303) Establish the heat balance constraint: Where: η EB is the heating efficiency of the electric boiler; (304) Establish the gas balance constraint: 。 5. The method for collaborative operation of energy and carbon emissions in a multi-energy-coupled sewage treatment plant according to claim 1, wherein The specific process of step (4) is as follows: Use the MILP solver on the GAMS platform to solve the collaborative operation model of energy and carbon emissions in a multi-energy-coupled sewage treatment plant to obtain the operation strategy of the sewage treatment plant.

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