A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage.

Abstract

The present invention discloses a reverse osmosis desalination plant scheduling method that takes into account the pressure-delayed osmosis process, comprising the following steps: 1) obtaining basic parameters of the desalination plant; 2) modeling the desalination process based on the basic parameters to obtain a desalination plant equipment unit model; 3) establishing desalination plant operation constraints based on the basic desalination plant equipment unit model; 4) constructing an overall desalination plant scheduling model based on the desalination plant equipment unit model and the desalination plant operation constraints; and 5) solving the overall desalination plant scheduling model to obtain an optimized desalination plant scheduling plan. The present invention provides a reverse osmosis desalination plant scheduling method that takes into account the pressure-delayed osmosis process, enabling a more efficient and environmentally friendly desalination process.

Description

Technical Field

[0001] This invention relates to the field of integrated energy system technology, specifically a scheduling method for a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage. Background Technology

[0002] Currently, approximately 40% of the world's population faces the severe challenge of freshwater scarcity. Against this backdrop, seawater desalination technology has experienced rapid development in water-scarce countries. Reverse osmosis technology, as the most widely used seawater desalination method, has seen its energy consumption per ton of water reduced to 3... ～ The desalination process produces 5 kWh of salt, but energy costs still account for about 40% of the total cost, indicating that the technology still suffers from high energy consumption. Furthermore, the concentrated brine produced during desalination contains a large number of chemical elements; direct discharge of this brine would severely impact the nearshore environment and marine ecosystem.

[0003] To reduce the energy consumption of reverse osmosis desalination technology, researchers have discovered that the salinity gradient in concentrated brine can be recycled. Pressure-delayed osmosis (PDOS) technology applies pressure to the high-concentration solution side, slowing the permeation process of water molecules from the low-concentration solution to the high-concentration solution. This creates significant hydraulic pressure on the high-concentration solution side, driving a turbine to generate electricity. This technology not only converts the chemical energy in the brine into electrical energy for recovery, reducing the energy consumption of desalination, but also mitigates the pollution of the ocean caused by high-concentration brine.

[0004] However, most current research literature on seawater desalination plants focuses on describing the reverse osmosis process, with few studies providing detailed descriptions of desalination plants that combine reverse osmosis and pressure-delayed osmosis. Furthermore, existing research often neglects the impact of seawater temperature and concentration on energy consumption when discussing desalination processes. Summary of the Invention

[0005] The purpose of this invention is to provide a method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, comprising the following steps:

[0006] 1) Obtain the basic parameters of the seawater desalination plant;

[0007] 2) Based on the basic parameters, the seawater desalination process is modeled to obtain the equipment unit model of the seawater desalination plant;

[0008] 3) Based on the basic model of the equipment unit model of the seawater desalination plant, establish the operating constraints of the seawater desalination plant;

[0009] 4) Combining the equipment unit model of the seawater desalination plant and the operating constraints of the seawater desalination plant, construct the overall scheduling model of the seawater desalination plant;

[0010] 5) Solve the overall scheduling model of the seawater desalination plant to obtain the optimal scheduling scheme for the seawater desalination plant.

[0011] Furthermore, the basic parameters of a seawater desalination plant include the parameters of each piece of equipment, time-of-use electricity price, freshwater load, predicted wind power, seawater concentration, and seawater temperature.

[0012] Furthermore, the seawater desalination plant equipment unit model includes a water intake pump model, a reverse osmosis high-pressure pump unit model, a pressure delayed osmosis unit model, and an energy storage device model.

[0013] Furthermore, the water intake pump model is shown below:

[0014]

[0015] Wherein, the subscript t represents the time period t; and These represent the water intake pump power and water intake flow rate for the t-th time period, respectively; H In The pump head is given by ρ; ρ and g are the density of water and the acceleration due to gravity, respectively; η is the pump head. In To improve the operating efficiency of the water pump;

[0016] The reverse osmosis high-pressure pump unit model is shown below:

[0017]

[0018] in, Power of the high-pressure pump for the reverse osmosis module; The seawater flow rate for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO For the operating efficiency of the high-pressure pump of the reverse osmosis module; q PR,t K represents the product's permeate flow rate. RO 、S RO These are the permeability coefficient and membrane area of ​​the permeable membrane, respectively. T is the feed water temperature coefficient; N is the water temperature; and N is the number of reverse osmosis membranes. For the hydraulic differential pressure of the reverse osmosis module; p BR,t and p PR,t The water pressures of the concentrated brine and the product water are respectively; Δπ t π represents the osmotic pressure difference of the reverse osmosis module. FD,t π BR,t and π PR,t These are the osmotic pressures of the feed seawater, concentrated brine, and product water, respectively. C is the concentration polarization coefficient; FD,t C BR,t and C PR,t q represents the concentrations of feed seawater, concentrated brine, and product water, respectively; κ is the ratio of solution osmotic pressure to solution concentration. BR,t R is the concentrated brine flow rate; R is the reverse osmosis recovery rate.

[0019] The pressure-delayed infiltration unit model includes equations for calculating water flow rate, power generation, hydraulic pressure difference in the pressure-delayed infiltration module, and power consumption of the high-pressure pump in the pressure-delayed infiltration module.

[0020] The equation for calculating water flow rate in the pressure-delayed permeation module is shown below:

[0021]

[0022] Where, q w,t This refers to the flow rate of water passing through the semipermeable membrane. This refers to the temperature coefficient of concentrated brine in the concentrated brine tank. The pressure delay permeation module has a hydraulic differential; A, k, S, D, and β are the membrane's permeability coefficient, mass transfer coefficient, membrane structural parameters, volume diffusion coefficient, and solute permeability, respectively.

[0023] The equation for calculating the power generation of pressure-delayed infiltration is shown below:

[0024]

[0025] in, It is the power generation capacity of the water turbine; η TUR For the operating efficiency of the water turbine;

[0026] The equation for calculating the hydraulic differential pressure in the pressure-delayed permeation module is shown below:

[0027]

[0028] in, p FS,t and p w,t These are hydraulic pressure for pressurized high-salinity extraction solution, hydraulic pressure for low-salinity feed solution, and hydraulic pressure for water passing through a semi-permeable membrane;

[0029] The power consumption calculation equation for the high-pressure pump of the pressure-delayed permeation module is shown below:

[0030]

[0031] in, Power consumption of the high-pressure pump in the reverse osmosis module; For the concentrated brine flow rate entering the pressure-delayed permeation module; η PRO To improve the operating efficiency of the high-pressure pump in the reverse osmosis module;

[0032] The energy storage device includes a water storage tank model and an electric energy storage device model;

[0033] The reservoir model is shown below:

[0034]

[0035] in, and The water levels in the clear water tank, product water tank, and concentrated brine tank during time period t are respectively. and The water levels in the clear water tank and the product water tank at time t-1 are respectively; r Pre This represents the ratio of pretreated seawater to feed water flow rate. This refers to the water flow rate from the product's water tank. A represents the seawater flow rate for the pressure-delayed permeation module. CLT A PRT and A BRT The bottom areas of the clear water tank, product water tank, and concentrated brine tank are respectively; T T The total number of time periods in a scheduling cycle; and These represent the initial and final values ​​of the water level in the clear water reservoir during the scheduling cycle; and These represent the initial and final values ​​of the product pool water level during the scheduling cycle; and These represent the initial and final values ​​of the water level in the concentrated brine pool during the scheduling cycle; h CLT These are the upper and lower limits of the water level in the clear water pool; h PRT These are the upper and lower limits of the water level in the product pool, respectively. h BRT These represent the upper and lower limits of the water level in the concentrated brine tank, respectively; q t Δt represents the total freshwater production of all reverse osmosis units during time period t; Δt is the scheduling time interval.

[0036] The concentration and temperature balance of the solution in the reservoir are shown below:

[0037]

[0038] Among them, C BRT,t C BRT,t-1 These represent the concentrations of concentrated brine in the brine tank at time periods t and t-1, respectively. Let C be the water intake flow in the t-th time period; In,t T represents the water concentration. In,t T BR,t The water intake temperature of the water pump and the temperature of the concentrated brine;

[0039] The concentration balance of the pressure-delayed osmosis module in the reservoir is shown below:

[0040]

[0041] in, The concentration of the discharged water;

[0042] The energy storage model is shown below:

[0043]

[0044] in, and These represent the charging and discharging power of the energy storage system; η CH and η DCH These refer to the charging and discharging efficiencies of the energy storage system. The energy stored at time t and time t-1 is the energy stored during the time period t. and These are 0-1 variables representing the charging and discharging states of electrical energy storage; and These represent the initial and final values ​​of the energy storage capacity within the dispatch cycle; P CH , These are the lower and upper limits of the charging power for electric energy storage, respectively. P DCH , These represent the lower and upper limits of the energy storage discharge power, respectively; Δt is the scheduling time interval. E BE , These represent the lower and upper limits of the energy storage capacity, respectively.

[0045] Furthermore, the operational constraints of the seawater desalination plant include intake pump flow constraints, intake pump power constraints, intake pump start-stop constraints, linear energy consumption constraints of the high-pressure pump in the reverse osmosis module, flow constraints of the high-pressure pump in the reverse osmosis module and the pressure delayed osmosis module, high-pressure pump power constraints, high-pressure pump operating pressure constraints, high-pressure pump start-stop frequency constraints, total water production constraints of the reverse osmosis unit, turbine power constraints, turbine start-stop constraints, wind turbine operation constraints, and power balance constraints.

[0046] Furthermore, the flow rate constraint of the water intake pump is as follows:

[0047]

[0048] in, This refers to the water intake pump flow rate; A 0-1 variable representing the working state of the water intake pump; and q In These are the upper and lower limits of the water intake pump flow rate, respectively.

[0049] The power constraints of the water intake pump are as follows:

[0050]

[0051] Among them, P In,UP and P In,DN These are the upper and lower power limits for the water intake pump, respectively. The power of the water pump during time period t and time period t-1; This refers to the upper and lower limits of the water pump power. These are 0-1 variables characterizing the operating status of the water intake pumps during time periods t and t-1.

[0052] The start / stop constraints for the water intake pump are as follows:

[0053]

[0054] Among them, C In , These are the single start-up and shutdown costs of the water intake pump and its total start-up and shutdown costs over time period t; M In This refers to the maximum number of times the water intake pump can be started and stopped within the scheduling cycle. A 0-1 variable representing the operating status of the water intake pump during time period t+1;

[0055] The flow constraints of the high-pressure pumps in the reverse osmosis module and the pressure-delayed permeation module are shown below:

[0056]

[0057] in, The seawater flow rate for the reverse osmosis module; A 0-1 variable representing the operating state of the high-pressure pump in the reverse osmosis module; and These are the upper and lower limits of the flow rate of the high-pressure pump in the reverse osmosis module, respectively. The seawater flow rate for the pressure-delayed permeation module; 0-1 variables characterizing the operating state of the high-pressure pump in the pressure-delayed permeation module; and These are the upper and lower limits of the high-pressure pump flow rate for the pressure delay permeation module, respectively.

[0058] The linear constraint on the energy consumption of the high-pressure pump in the reverse osmosis module is shown below:

[0059]

[0060] in, These are the upper and lower limits of the operating pressure for the reverse osmosis module; Power of the high-pressure pump for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO To improve the operating efficiency of the high-pressure pump in the reverse osmosis module; This refers to the output power of the high-pressure pump in the reverse osmosis module.

[0061] The power constraints of the high-pressure pumps in the reverse osmosis module and the pressure delayed osmosis module are shown below:

[0062]

[0063] Among them, P RO,UP and P RO,DN These are the upper and lower power limits for the high-pressure pump of the reverse osmosis module, respectively. The power of the high-pressure pump of the reverse osmosis module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the reverse osmosis module; P is a 0-1 variable characterizing the operating status of the high-pressure pump of the reverse osmosis module during time period t and t-1. PRO,UP and P PRO,DN These are the upper and lower power limits of the high-pressure pump in the pressure delay permeation module, respectively. The power of the high-pressure pump in the pressure-delayed permeation module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the pressure-delayed permeation module; The 0-1 variables characterize the operating status of the high-pressure pump in the pressure-delayed permeation module during time period t and t-1.

[0064] The operating pressure constraints of the high-pressure pumps for the reverse osmosis module and the pressure-delayed osmosis module are as follows:

[0065]

[0066] in, The operating pressure of the reverse osmosis unit during time period t and time period t-1; This represents the upper and lower limits of the operating pressure of the reverse osmosis module; p RO,UP and p RO,DN This refers to the upper limit of the increase and decrease in operating pressure of the reverse osmosis module per unit time period; Δ p RO These are the upper and lower limits of the pressure difference in the reverse osmosis module; The pressure of the pressure-delayed permeation unit during time period t and time period t-1; p represents the upper and lower limits of the operating pressure of the pressure-delayed permeation module. PRO,UP and p PRO,DN The upper limit of the pressure increment and decrement per unit time period for the pressure delay permeation module; Δπ t This refers to the osmotic pressure difference of the reverse osmosis module; Pressure difference for the reverse osmosis module;

[0067] The constraints on the number of start-stop cycles of the high-pressure pump are as follows:

[0068]

[0069] Among them, M RO M represents the maximum permissible number of start-stop cycles for the high-pressure pump of the reverse osmosis module within the scheduling cycle. PRO This represents the maximum permissible number of start-stop cycles for the high-pressure pump in the pressure delay permeation module within the scheduling cycle.

[0070] The total permeate capacity constraint of the reverse osmosis unit is shown below:

[0071]

[0072] Among them, S RO Δt is the lower limit of freshwater production within the scheduling cycle; q is the scheduling time interval; Δt is the lower limit of freshwater production within the scheduling cycle. PR,t The product's permeate flow rate;

[0073] The turbine flow constraints are shown below:

[0074]

[0075] Where, q w,t The turbine flow rate; A 0-1 variable characterizing the operating state of the water turbine; and q In These are the upper and lower limits of the turbine's flow rate, respectively. q w , These are the lower and upper limits of the turbine's flow rate;

[0076] The power constraints of the water turbine are as follows:

[0077]

[0078] Among them, P TUR,UP and P TUR,DN These are the upper and lower power limits for the turbine's upward and downward travel, respectively. This represents the power output of the turbine during time interval t and time interval t-1. These are the upper and lower limits of the turbine's power output; The variables are 0-1 variables that characterize the operating status of the turbine during time period t and t-1.

[0079] The turbine start-up and shutdown constraints are as follows:

[0080]

[0081] Among them, M TUR This represents the maximum number of times the turbine can be started and stopped within the scheduling cycle.

[0082] The operating constraints of wind turbine units are as follows:

[0083]

[0084] in, and These are the predicted power and reduced power of the wind turbine units in the desalination plant, respectively.

[0085] The power balance constraints are as follows:

[0086]

[0087] in, To facilitate the purchase of electricity from the power distribution network by the desalination plant; To supply the electricity sold by the desalination plant to the power distribution network; To limit the interaction power between the desalination plant and the distribution network; Power of the high-pressure pump for the reverse osmosis module; Let be the power of the water intake pump in the t-th time period; and These refer to the charging and discharging power of the energy storage system, respectively. Power consumption of the high-pressure pump in the reverse osmosis module; It refers to the power generation capacity of the water turbine.

[0088] Furthermore, the objective function of the overall scheduling model for the seawater desalination plant is as follows:

[0089] minC=C OP +C SU +C EN +C BE +C WG +C AW +C ENV (37)

[0090] Among them, T T C represents the number of time periods in the scheduling cycle; C represents the total operating cost of the desalination plant. For equipment operation and maintenance costs, For equipment start-up and shutdown costs, To mitigate the power interaction costs between power plants and distribution networks, For the operation and maintenance costs of energy storage, For wind turbine operation and maintenance costs, As punishment for abandoning the wind, Punishment for discharging concentrated brine.

[0091] Furthermore, equipment operation and maintenance costs Equipment start-up and shutdown costs Power interaction cost between desalination plant and power distribution network Energy storage operation and maintenance costs Wind turbine operation and maintenance costs wind abandonment punishment Discharging concentrated brine is a penalty As shown below:

[0092]

[0093] in and These are the operation and maintenance cost coefficients for the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficients for the high-pressure pump of the pressure-delayed osmosis module, and the operation and maintenance cost coefficients for the turbine. and These are the costs for a single start-up and shutdown of the high-pressure pump in the reverse osmosis module, the cost for a single start-up and shutdown of the high-pressure pump in the pressure-delayed osmosis module, and the cost for a single start-up and shutdown of the turbine. These are the unit prices for electricity purchased / sold by the desalination plant from the power distribution network; This is the coefficient for the operation and maintenance costs of energy storage. This is the coefficient for wind turbine operation and maintenance costs; This is the wind curtailment penalty coefficient; C is the environmental pollution penalty coefficient. ST The standard concentration for seawater discharge; The concentration of the discharged water.

[0094] Furthermore, the constraints of the overall scheduling model of the seawater desalination plant are the operating constraints of the seawater desalination plant (20)-(36).

[0095] Furthermore, tools for solving the overall scheduling model of a seawater desalination plant include the Gurobi solver.

[0096] The technical effects of this invention are undeniable. This invention provides a method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, which can achieve a more efficient and environmentally friendly seawater desalination process. Attached Figure Description

[0097] Figure 1 This is a flowchart illustrating the solution process of the method of the present invention.

[0098] Figure 2 This is a structural energy flow diagram of a seawater desalination plant according to the method of the present invention.

[0099] Figure 3 This is a flow chart of a reverse osmosis-pressure delayed osmosis seawater desalination plant according to the method of the present invention.

[0100] Figure 4 This is a map showing seawater temperature in winter and summer.

[0101] Figure 5 This is a water load forecast diagram.

[0102] Figure 6 This is the scheduling result for the reverse osmosis desalination plant during winter.

[0103] Figure 7 This is the scheduling result of a reverse osmosis-pressure delayed permeation desalination plant during winter. Detailed Implementation

[0104] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0105] Example 1:

[0106] See Figures 1 to 7 A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage includes the following steps:

[0107] 1) Obtain the basic parameters of the seawater desalination plant;

[0108] 2) Based on the basic parameters, the seawater desalination process is modeled to obtain the equipment unit model of the seawater desalination plant;

[0109] 3) Based on the basic model of the equipment unit model of the seawater desalination plant, establish the operating constraints of the seawater desalination plant;

[0110] 4) Combining the equipment unit model of the seawater desalination plant and the operating constraints of the seawater desalination plant, construct the overall scheduling model of the seawater desalination plant;

[0111] 5) Solve the overall scheduling model of the seawater desalination plant to obtain the optimal scheduling scheme for the seawater desalination plant.

[0112] Example 2:

[0113] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage is provided. The technical content is the same as in Example 1. Furthermore, the basic parameters of the seawater desalination plant include the parameters of each piece of equipment in the seawater desalination plant, the time-of-use electricity purchase / sale price, the freshwater load, the predicted wind power, the seawater concentration, and the seawater temperature.

[0114] Example 3:

[0115] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed osmosis stage, with the same technical content as any one of Embodiments 1-2. Further, the seawater desalination plant equipment unit model includes a water intake pump model, a reverse osmosis high-pressure pump unit model, a pressure-delayed osmosis unit model, and an energy storage device model.

[0116] Example 4:

[0117] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, with the same technical content as any one of Examples 1-3, and further, the water intake pump model is shown below:

[0118]

[0119] Wherein, the subscript t represents the time period t; and These represent the water intake pump power and water intake flow rate for the t-th time period, respectively; H In The pump head is given by ρ; ρ and g are the density of water and the acceleration due to gravity, respectively; η is the pump head. In To improve the operating efficiency of the water pump;

[0120] The reverse osmosis high-pressure pump unit model is shown below:

[0121]

[0122] in, Power of the high-pressure pump for the reverse osmosis module; The seawater flow rate for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO For the operating efficiency of the high-pressure pump of the reverse osmosis module; q PR,t K represents the product's permeate flow rate. RO 、S RO These are the permeability coefficient and membrane area of ​​the permeable membrane, respectively. T is the feed water temperature coefficient; N is the water temperature; and N is the number of reverse osmosis membranes. For the hydraulic differential pressure of the reverse osmosis module; p BR,t and p PR,t The water pressures of the concentrated brine and the product water are respectively; Δπ t π represents the osmotic pressure difference of the reverse osmosis module. FD,t π BR,t and π PR,t These are the osmotic pressures of the feed seawater, concentrated brine, and product water, respectively. C is the concentration polarization coefficient; FD,t C BR,t and C PR,t q represents the concentrations of feed seawater, concentrated brine, and product water, respectively; κ is the ratio of solution osmotic pressure to solution concentration. BR,t R is the concentrated brine flow rate; R is the reverse osmosis recovery rate.

[0123] The pressure-delayed infiltration unit model includes equations for calculating water flow rate, power generation, hydraulic pressure difference in the pressure-delayed infiltration module, and power consumption of the high-pressure pump in the pressure-delayed infiltration module.

[0124] The equation for calculating water flow rate in the pressure-delayed permeation module is shown below:

[0125]

[0126] Where, q w,t This refers to the flow rate of water passing through the semipermeable membrane. This refers to the temperature coefficient of concentrated brine in the concentrated brine tank. The pressure delay permeation module has a hydraulic differential; A, k, S, D, and β are the membrane's permeability coefficient, mass transfer coefficient, membrane structural parameters, volume diffusion coefficient, and solute permeability, respectively.

[0127] The equation for calculating the power generation of pressure-delayed infiltration is shown below:

[0128]

[0129] in, It is the power generation capacity of the water turbine; η TUR For the operating efficiency of the water turbine;

[0130] The equation for calculating the hydraulic differential pressure in the pressure-delayed permeation module is shown below:

[0131]

[0132] in, p FS,t and p w,t These are hydraulic pressure for pressurized high-salinity extraction solution, hydraulic pressure for low-salinity feed solution, and hydraulic pressure for water passing through a semi-permeable membrane;

[0133] The power consumption calculation equation for the high-pressure pump of the pressure-delayed permeation module is shown below:

[0134]

[0135] in, Power consumption of the high-pressure pump in the reverse osmosis module; For the concentrated brine flow rate entering the pressure-delayed permeation module; η PRO To improve the operating efficiency of the high-pressure pump in the reverse osmosis module;

[0136] The energy storage device includes a water storage tank model and an electric energy storage device model;

[0137] The reservoir model is shown below:

[0138]

[0139] in, and The water levels in the clear water tank, product water tank, and concentrated brine tank during time period t are respectively. and The water levels in the clear water tank and the product water tank at time t-1 are respectively; r Pre This represents the ratio of pretreated seawater to feed water flow rate. This refers to the water flow rate from the product's water tank. A represents the seawater flow rate for the pressure-delayed permeation module. CLT A PRT and A BRTThe bottom areas of the clear water tank, product water tank, and concentrated brine tank are respectively; T T The total number of time periods in a scheduling cycle; and These represent the initial and final values ​​of the water level in the clear water reservoir during the scheduling cycle; and These represent the initial and final values ​​of the product pool water level during the scheduling cycle; and These represent the initial and final values ​​of the water level in the concentrated brine pool during the scheduling cycle; h CLT These are the upper and lower limits of the water level in the clear water pool; h PRT These are the upper and lower limits of the water level in the product pool, respectively. h BRT These represent the upper and lower limits of the water level in the concentrated brine tank, respectively; q t Δt represents the total freshwater production of all reverse osmosis units during time period t; Δt is the scheduling time interval.

[0140] The concentration and temperature balance of the solution in the reservoir are shown below:

[0141]

[0142] Among them, C BRT,t C BRT,t-1 These represent the concentrations of concentrated brine in the brine tank at time periods t and t-1, respectively. Let C be the water intake flow in the t-th time period; In,t T represents the water concentration. In,t T BR,t The water intake temperature of the water pump and the temperature of the concentrated brine;

[0143] The concentration balance of the pressure-delayed osmosis module in the reservoir is shown below:

[0144]

[0145] in, The concentration of the discharged water;

[0146] The energy storage model is shown below:

[0147]

[0148] in, and These represent the charging and discharging power of the energy storage system; η CH and η DCH These refer to the charging and discharging efficiencies of the energy storage system. The energy stored at time t and time t-1 is the energy stored during the time period t. and These are 0-1 variables representing the charging and discharging states of electrical energy storage; and These represent the initial and final values ​​of the energy storage capacity within the dispatch cycle; P CH , These are the lower and upper limits of the charging power for electric energy storage, respectively. P DCH , These represent the lower and upper limits of the energy storage discharge power, respectively; Δt is the scheduling time interval. E BE , These represent the lower and upper limits of the energy storage capacity, respectively.

[0149] Example 5:

[0150] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed osmosis stage, with the same technical content as any one of embodiments 1-4. Further, the operating constraints of the seawater desalination plant include intake pump flow constraints, intake pump power constraints, intake pump start-stop constraints, linear constraints on the energy consumption of the high-pressure pump in the reverse osmosis module, flow constraints of the high-pressure pumps in the reverse osmosis module and the pressure-delayed osmosis module, high-pressure pump power constraints, high-pressure pump operating pressure constraints, high-pressure pump start-stop frequency constraints, total water production constraints of the reverse osmosis unit, turbine power constraints, turbine start-stop constraints, wind turbine operation constraints, and power balance constraints.

[0151] Example 6:

[0152] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, with the same technical content as any one of Examples 1-5, further wherein the intake pump flow constraint is as follows:

[0153]

[0154] in, This refers to the water intake pump flow rate; A 0-1 variable representing the working state of the water intake pump; and q In These are the upper and lower limits of the water intake pump flow rate, respectively.

[0155] The power constraints of the water intake pump are as follows:

[0156]

[0157] Among them, P In,UP and P In,DN These are the upper and lower power limits for the water intake pump, respectively. The power of the water pump during time period t and time period t-1; This refers to the upper and lower limits of the water pump power. These are 0-1 variables characterizing the operating status of the water intake pumps during time periods t and t-1.

[0158] The start / stop constraints for the water intake pump are as follows:

[0159]

[0160] Among them, C In , These are the single start-up and shutdown costs of the water intake pump and its total start-up and shutdown costs over time period t; M In This refers to the maximum number of times the water intake pump can be started and stopped within the scheduling cycle. A 0-1 variable representing the operating status of the water intake pump during time period t+1;

[0161] The flow constraints of the high-pressure pumps in the reverse osmosis module and the pressure-delayed permeation module are shown below:

[0162]

[0163] in, The seawater flow rate for the reverse osmosis module; A 0-1 variable representing the operating state of the high-pressure pump in the reverse osmosis module; and These are the upper and lower limits of the flow rate of the high-pressure pump in the reverse osmosis module, respectively. The seawater flow rate for the pressure-delayed permeation module; 0-1 variables characterizing the operating state of the high-pressure pump in the pressure-delayed permeation module; and These are the upper and lower limits of the high-pressure pump flow rate for the pressure delay permeation module, respectively.

[0164] The linear constraint on the energy consumption of the high-pressure pump in the reverse osmosis module is shown below:

[0165]

[0166] in, These are the upper and lower limits of the operating pressure for the reverse osmosis module; Power of the high-pressure pump for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO To improve the operating efficiency of the high-pressure pump in the reverse osmosis module; This refers to the output power of the high-pressure pump in the reverse osmosis module.

[0167] The power constraints of the high-pressure pumps in the reverse osmosis module and the pressure delayed osmosis module are shown below:

[0168]

[0169]

[0170] Among them, P RO,UP and P RO,DN These are the upper and lower power limits for the high-pressure pump of the reverse osmosis module, respectively. The power of the high-pressure pump of the reverse osmosis module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the reverse osmosis module; P is a 0-1 variable characterizing the operating status of the high-pressure pump of the reverse osmosis module during time period t and t-1. PRO,UP and P PRO,DN These are the upper and lower power limits of the high-pressure pump in the pressure delay permeation module, respectively. The power of the high-pressure pump in the pressure-delayed permeation module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the pressure-delayed permeation module; The 0-1 variables characterize the operating status of the high-pressure pump in the pressure-delayed permeation module during time period t and t-1.

[0171] The operating pressure constraints of the high-pressure pumps for the reverse osmosis module and the pressure-delayed osmosis module are as follows:

[0172]

[0173] in, The operating pressure of the reverse osmosis unit during time period t and time period t-1; This represents the upper and lower limits of the operating pressure of the reverse osmosis module; p RO,UP and p RO,DN This refers to the upper limit of the increase and decrease in operating pressure of the reverse osmosis module per unit time period; Δ p RO These are the upper and lower limits of the pressure difference in the reverse osmosis module; The pressure of the pressure-delayed permeation unit during time period t and time period t-1; p represents the upper and lower limits of the operating pressure of the pressure-delayed permeation module. PRO,UP and p PRO,DN The upper limit of the pressure increment and decrement per unit time period for the pressure delay permeation module; Δπ t This refers to the osmotic pressure difference of the reverse osmosis module; Pressure difference for the reverse osmosis module;

[0174] The constraints on the number of start-stop cycles of the high-pressure pump are as follows:

[0175]

[0176]

[0177] Among them, M RO M represents the maximum permissible number of start-stop cycles for the high-pressure pump of the reverse osmosis module within the scheduling cycle. PRO This represents the maximum permissible number of start-stop cycles for the high-pressure pump in the pressure delay permeation module within the scheduling cycle.

[0178] The total permeate capacity constraint of the reverse osmosis unit is shown below:

[0179]

[0180] Among them, S RO Δt is the lower limit of freshwater production within the scheduling cycle; q is the scheduling time interval; Δt is the lower limit of freshwater production within the scheduling cycle. PR,t The product's permeate flow rate;

[0181] The turbine flow constraints are shown below:

[0182]

[0183] Where, q w,t The turbine flow rate; A 0-1 variable characterizing the operating state of the water turbine; and q In These are the upper and lower limits of the turbine's flow rate, respectively. q w , These are the lower and upper limits of the turbine's flow rate;

[0184] The power constraints of the water turbine are as follows:

[0185]

[0186] Among them, P TUR,UP and P TUR,DN These are the upper and lower power limits for the turbine's upward and downward travel, respectively. This represents the power output of the turbine during time interval t and time interval t-1. These are the upper and lower limits of the turbine's power output; The variables are 0-1 variables that characterize the operating status of the turbine during time period t and t-1.

[0187] The turbine start-up and shutdown constraints are as follows:

[0188]

[0189] Among them, M TUR This represents the maximum number of times the turbine can be started and stopped within the scheduling cycle.

[0190] The operating constraints of wind turbine units are as follows:

[0191]

[0192] in, and These are the predicted power and reduced power of the wind turbine units in the desalination plant, respectively.

[0193] The power balance constraints are as follows:

[0194]

[0195] in, To facilitate the purchase of electricity from the power distribution network by the desalination plant; To supply the electricity sold by the desalination plant to the power distribution network; To limit the interaction power between the desalination plant and the distribution network; Power of the high-pressure pump for the reverse osmosis module; Let be the power of the water intake pump in the t-th time period; and These refer to the charging and discharging power of the energy storage system, respectively. Power consumption of the high-pressure pump in the reverse osmosis module; It refers to the power generation capacity of the water turbine.

[0196] Example 7:

[0197] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, with the same technical content as any one of Examples 1-6. Furthermore, the objective function of the overall scheduling model for the seawater desalination plant is as follows:

[0198] minC=C OP +C SU +C EN +C BE +C WG +C AW +C ENV (37)

[0199] Among them, T T C represents the number of time periods in the scheduling cycle; C represents the total operating cost of the desalination plant. For equipment operation and maintenance costs, For equipment start-up and shutdown costs, To mitigate the power interaction costs between power plants and distribution networks, For the operation and maintenance costs of energy storage, For wind turbine operation and maintenance costs, As punishment for abandoning the wind, Punishment for discharging concentrated brine.

[0200] Example 8:

[0201] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, with the same technical content as any one of Examples 1-7, further reducing equipment operation and maintenance costs. Equipment start-up and shutdown costs Power interaction cost between desalination plant and power distribution network Energy storage operation and maintenance costs Wind turbine operation and maintenance costs wind abandonment punishment Discharging concentrated brine is a penalty As shown below:

[0202]

[0203] in and These are the operation and maintenance cost coefficients for the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficients for the high-pressure pump of the pressure-delayed osmosis module, and the operation and maintenance cost coefficients for the turbine. and These are the costs for a single start-up and shutdown of the high-pressure pump in the reverse osmosis module, the cost for a single start-up and shutdown of the high-pressure pump in the pressure-delayed osmosis module, and the cost for a single start-up and shutdown of the turbine. These are the unit prices for electricity purchased / sold by the desalination plant from the power distribution network; This is the coefficient for the operation and maintenance costs of energy storage. This is the coefficient for wind turbine operation and maintenance costs; This is the wind curtailment penalty coefficient; C is the environmental pollution penalty coefficient. ST The standard concentration for seawater discharge; The concentration of the discharged water.

[0204] Example 9:

[0205] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure delay permeation stage, with the same technical content as any one of Examples 1-8. Further, the constraints of the overall scheduling model of the seawater desalination plant are the seawater desalination plant operation constraints (20)-(36).

[0206] Example 10:

[0207] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, with the same technical content as any one of Examples 1-9. Furthermore, the tool for solving the overall scheduling model of the seawater desalination plant includes the Gurobi solver.

[0208] Example 11:

[0209] A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, comprising the following steps:

[0210] Input the basic parameters of the seawater desalination plant;

[0211] Based on the basic parameters, the seawater desalination process is modeled to obtain the equipment unit model of the seawater desalination plant;

[0212] Based on the above basic model, operational constraints for seawater desalination plants are established.

[0213] Solve the overall model of the above seawater desalination plant to obtain the optimal scheduling scheme for the seawater desalination plant.

[0214] The specific implementation steps are as follows:

[0215] Basic parameters:

[0216] The basic parameters of a seawater desalination plant include the parameters of each piece of equipment, time-of-use electricity price, freshwater load, predicted wind power, seawater concentration, and seawater temperature. Detailed parameters will be given in the following examples.

[0217] Equipment Model:

[0218] The equipment unit model of a seawater desalination plant includes a water intake pump model, a reverse osmosis high-pressure pump unit model, a pressure delayed osmosis unit model, and an energy storage device model.

[0219] The energy consumption characteristics of the water intake pump are shown below:

[0220]

[0221] Where the subscript t represents the time period t; P Int and q Int These represent the water intake pump power and water intake flow rate for the t-th time period, respectively; H In The pump head is given by ρ; ρ and g are the density of water and the acceleration due to gravity, respectively; η is the pump head. In This is to measure the operating efficiency of the water pump. For simplicity, the time period subscript 't' for the variable will not be specifically explained below.

[0222] The energy consumption characteristics of the high-pressure pump in the reverse osmosis module are shown below:

[0223]

[0224] Where P ROt Power of the high-pressure pump for the reverse osmosis module; The seawater flow rate for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO This refers to the operating efficiency of the high-pressure pump in the reverse osmosis module.

[0225] The equation for calculating the flow rate of a high-pressure pump and the definitions of its parameters are shown below:

[0226]

[0227] π FD,t =κC FD,t ,π BR,t =κC BR,t ,π PR,t =κC PR,t (7)

[0228]

[0229] Where q PR,t K represents the product's permeate flow rate. RO A RO These are the permeability coefficient and membrane area of ​​the permeable membrane, respectively. T is the feed water temperature coefficient; N is the water temperature; and N is the number of reverse osmosis membranes. For the hydraulic differential pressure of the reverse osmosis module; p BR,t and p PR,t The water pressures of the concentrated brine and the product water are respectively; Δπ t π represents the osmotic pressure difference of the reverse osmosis module. FD,t π BR,t and π PR,t These are the osmotic pressures of the feed seawater, concentrated brine, and product water, respectively; C t F C is the concentration polarization coefficient; FD,t C BR,t and C PR,t , respectively, represent the concentrations of feed seawater, concentrated brine, and product water; κ is the ratio coefficient of solution osmotic pressure to solution concentration.

[0230] The flow balance of the reverse osmosis module is shown below:

[0231]

[0232] Where q PR,t q represents the product's water flow rate; BR,t R is the concentrated brine flow rate; R is the reverse osmosis recovery rate.

[0233] The equation for calculating water flow rate in a pressure-delayed permeation module is shown below:

[0234]

[0235] Where q w,t This refers to the flow rate of water passing through the semipermeable membrane. This refers to the temperature coefficient of concentrated brine in the concentrated brine tank. The pressure delay permeation module has a hydraulic differential; A, k, S, D, and β are the membrane's permeability coefficient, mass transfer coefficient, membrane structural parameters, volume diffusion coefficient, and solute permeability, respectively.

[0236] The power generation capacity of pressure-delayed infiltration is shown below:

[0237]

[0238] in It is the power generation capacity of the water turbine; η TUR For the operating efficiency of the water turbine.

[0239] The pressure differential of the pressure-delayed permeation module is shown below:

[0240]

[0241] in p FS,t and p w,t These are hydraulic pressure for extracting high-salinity solutions under pressure, hydraulic pressure for feeding low-salinity solutions, and hydraulic pressure for water passing through a semi-permeable membrane.

[0242] The power consumption of the high-pressure pump in the pressure-delayed permeation module is shown below:

[0243]

[0244] in Power consumption of the high-pressure pump in the reverse osmosis module; For the concentrated brine flow rate entering the pressure-delayed permeation module; η PRO This refers to the operating efficiency of the high-pressure pump in the reverse osmosis module.

[0245] The energy storage device includes a water tank model and an electric energy storage device model, wherein the water tank model is shown below:

[0246]

[0247] in, and The water levels in the clear water tank, product water tank, and concentrated brine tank during time period t are respectively. and The water levels in the clear water tank and the product water tank at time t-1 are respectively; r Pre q is the ratio of pretreated seawater to feed water flow rate; Outt This refers to the water flow rate from the product's water tank. A represents the seawater flow rate for the pressure-delayed permeation module. CLT A PRT and A BRT The bottom areas of the clear water tank, product water tank, and concentrated brine tank are respectively; T T The total number of time periods in a scheduling cycle; and These represent the initial and final values ​​of the water level in the clear water reservoir during the scheduling cycle; and These represent the initial and final values ​​of the product pool water level during the scheduling cycle; and These represent the initial and final values ​​of the water level in the concentrated brine pool during the scheduling cycle; h CLT These are the upper and lower limits of the water level in the clear water pool; h PRTThese are the upper and lower limits of the water level in the product pool, respectively. h BRT These represent the upper and lower limits of the water level in the concentrated brine tank, respectively; q t The total freshwater production of all reverse osmosis units during time period t is given.

[0248] The concentration and temperature balances of the solution in the pool are shown below:

[0249]

[0250] Where C BRT,t C BRT,t-1 These represent the concentrations of concentrated brine in the brine pool during time periods t and t-1, respectively.

[0251] The concentration balance of the pressure-delayed permeation module is shown below:

[0252]

[0253] in The concentration of the discharged water.

[0254] The energy storage model is shown below:

[0255]

[0256] in and These represent the charging and discharging power of the energy storage system; η CH and η DCH These refer to the charging and discharging efficiencies of the energy storage system. The energy stored at time t and time t-1 is the energy stored during the time period t. and These are 0-1 variables representing the charging and discharging states of electrical energy storage; and These represent the initial and final values ​​of the energy storage capacity within the dispatch cycle; P CH , These are the lower and upper limits of the charging power for electric energy storage, respectively. P DCH , These represent the lower and upper limits of the energy storage discharge power, respectively; Δt is the scheduling time interval.

[0257] Constraints:

[0258] The operational constraints of a seawater desalination plant include intake pump flow constraints, intake pump power constraints, intake pump start-up and shutdown constraints, high-pressure pump flow constraints, high-pressure pump power constraints, high-pressure pump operating pressure constraints, high-pressure pump start-up and shutdown frequency constraints, total water production constraints of the reverse osmosis unit, turbine power constraints, turbine start-up and shutdown constraints, wind turbine operation constraints, and power balance constraints.

[0259] The flow constraints of the water intake pump are as follows:

[0260]

[0261] in This refers to the water intake pump flow rate; A 0-1 variable representing the working state of the water intake pump; and q In These are the upper and lower limits of the water intake pump flow rate, respectively.

[0262] The power constraints of the water intake pump are as follows:

[0263]

[0264] Where P In,UP and P In,DN These are the upper and lower power limits for the water intake pump, respectively. The power of the water pump during time period t and time period t-1; This refers to the upper and lower limits of the water pump power. The variables are 0-1 variables that characterize the operating status of the water intake pumps during time periods t and t-1.

[0265] The start / stop constraints for the water intake pump are as follows:

[0266]

[0267] Where C In , These are the single start-up and shutdown costs of the water intake pump and its total start-up and shutdown costs over time period t; M In This represents the maximum number of times the water intake pump can be started and stopped within the scheduling cycle.

[0268] The flow constraints of the high-pressure pumps in the reverse osmosis module and the pressure-delayed permeation module are shown below:

[0269]

[0270] in The seawater flow rate for the reverse osmosis module; A 0-1 variable representing the operating state of the high-pressure pump in the reverse osmosis module; and These are the upper and lower limits of the flow rate of the high-pressure pump in the reverse osmosis module, respectively. The seawater flow rate for the pressure-delayed permeation module; 0-1 variables characterizing the operating state of the high-pressure pump in the pressure-delayed permeation module; and These are the upper and lower limits of the high-pressure pump flow rate for the pressure delay permeation module, respectively.

[0271] By processing the bilinear constraint in equation (2), we obtain:

[0272]

[0273] in These are the upper and lower limits of the working pressure of the reverse osmosis module. Equations (11) and (13) are similar.

[0274] The power constraints of the high-pressure pumps in the reverse osmosis module and the pressure delayed osmosis module are shown below:

[0275]

[0276] Where P RO,UP and P RO,DN These are the upper and lower power limits for the high-pressure pump of the reverse osmosis module, respectively. The power of the high-pressure pump of the reverse osmosis module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the reverse osmosis module; P is a 0-1 variable characterizing the operating status of the high-pressure pump of the reverse osmosis module during time period t and t-1. PRO,UP and P PRO,DN These are the upper and lower power limits of the high-pressure pump in the pressure delay permeation module, respectively. The power of the high-pressure pump in the pressure-delayed permeation module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the pressure-delayed permeation module; The variable is a 0-1 variable representing the operating status of the high-pressure pump in the pressure-delayed permeation module during time periods t and t-1.

[0277] The operating pressure constraints of the high-pressure pumps for the reverse osmosis module and the pressure-delayed osmosis module are as follows:

[0278]

[0279] In the formula, The operating pressure of the reverse osmosis unit during time period t and time period t-1; This represents the upper and lower limits of the operating pressure of the reverse osmosis module; p RO,UP and p RO,DN This refers to the upper limit of the increase and decrease in operating pressure of the reverse osmosis module per unit time period; Δ p ROThese are the upper and lower limits of the pressure difference in the reverse osmosis module; The pressure of the pressure-delayed permeation unit during time period t and time period t-1; p represents the upper and lower limits of the operating pressure of the pressure-delayed permeation module. PRO,UP and p PRO,DN This refers to the upper limit of the working pressure increment and decrement of the pressure delay permeation module per unit time period.

[0280]

[0281] Where C RO , These are the single start-up and shutdown costs of the high-pressure pump in the reverse osmosis module and its total start-up and shutdown costs within time period t; M RO C represents the maximum permissible number of start-stop cycles for the high-pressure pump of the reverse osmosis module within the scheduling cycle. PRO , These are the single start-up and shutdown costs of the high-pressure pump in the pressure-delayed permeation module and its total start-up and shutdown costs over time period t; M PRO This represents the maximum number of permissible start-stop cycles for the high-pressure pump in the pressure delay permeation module within the scheduling cycle.

[0282] The total permeate capacity constraint of the reverse osmosis unit is shown below:

[0283]

[0284] Where S RO Δt represents the lower limit of freshwater production within the scheduling cycle; Δt represents the scheduling time interval.

[0285] The turbine flow constraints are shown below:

[0286]

[0287] Where q w,t The turbine flow rate; A 0-1 variable characterizing the operating state of the water turbine; and q In These are the upper and lower limits of the turbine's flow rate, respectively.

[0288] The power constraints of the water turbine are as follows:

[0289]

[0290] Where P TUR,UP and P TUR,DN These are the upper and lower power limits for the turbine's upward and downward travel, respectively. This represents the power output of the turbine during time interval t and time interval t-1. These are the upper and lower limits of the turbine's power output; The variables are 0-1 variables that characterize the operating status of the turbine during time period t and t-1.

[0291] The turbine start-up and shutdown constraints are as follows:

[0292]

[0293] Where C TUR , These are the single start-up and shutdown costs of the turbine and its total start-up and shutdown costs over time period t; M TUR This represents the maximum number of times the turbine can be started and stopped within the scheduling cycle.

[0294] The operating constraints of wind turbine units are as follows:

[0295]

[0296] in and These are the predicted power and reduced power of the wind turbine units in the desalination plant, respectively.

[0297] The power balance constraints are as follows:

[0298]

[0299] in To facilitate the purchase of electricity from the power distribution network by the desalination plant; To supply the electricity sold by the desalination plant to the power distribution network; To reduce the power exchange limit between the plant and the distribution network.

[0300] Model solution:

[0301] Based on the desalination plant model described above, the objective function is as follows:

[0302] minC=C OP +C SU +C EN +C BE +C WG +C AW +C ENV (37)

[0303] Where T T The number of time periods in the scheduling cycle (T) T =24); C is the total operating cost of the desalination plant. For equipment operation and maintenance costs, For equipment start-up and shutdown costs, To mitigate the power interaction costs between power plants and distribution networks, For the operation and maintenance costs of energy storage, For wind turbine operation and maintenance costs, As punishment for abandoning the wind, Punishment for discharging concentrated brine.

[0304] The specific calculations for each cost and benefit are as follows:

[0305]

[0306] in and These are the operation and maintenance cost coefficients for the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficients for the high-pressure pump of the pressure-delayed osmosis module, and the operation and maintenance cost coefficients for the turbine. and These are the costs for a single start-up and shutdown of the high-pressure pump in the reverse osmosis module, the cost for a single start-up and shutdown of the high-pressure pump in the pressure-delayed osmosis module, and the cost for a single start-up and shutdown of the turbine. These are the unit prices for electricity purchased / sold by the desalination plant from the power distribution network; This is the coefficient for the operation and maintenance costs of energy storage. This is the coefficient for wind turbine operation and maintenance costs; This is the wind curtailment penalty coefficient; C is the environmental pollution penalty coefficient. ST This refers to the standard concentration for seawater discharge.

[0307] In summary, the model was solved using the Gurobi solver, and the optimized results were obtained.

[0308] Example 12:

[0309] The verification of a reverse osmosis seawater desalination plant scheduling method that takes into account the pressure-delayed permeation stage is as follows:

[0310] 1) Obtain the structural diagram of the seawater desalination plant. This diagram shows: the power busbar is connected to the power grid, energy storage, wind turbine generators, and energy-consuming equipment within the desalination plant. The wind farm supplies energy to the desalination plant, the power distribution network sells electricity to the desalination plant, and the desalination plant is permitted to connect its wind power to the grid.

[0311] As attached Figure 3 As shown, seawater is first pumped into the clear water tank for pretreatment. After flocculation and sedimentation, a portion enters the reverse osmosis unit for desalination. The high-pressure pump in the reverse osmosis unit pressurizes the water to achieve salt-water separation, and the concentrated brine enters the concentrated brine tank. The desalinated freshwater enters the product water tank to supply the water load. A portion of the seawater and concentrated brine enters the pressure delayed osmosis unit for energy recovery, and the energy obtained from the concentrated brine is collected by the turbine. The seawater desalination plant is equipped with clear water tanks, product water tanks, and concentrated brine tanks to achieve flexible control of the water production plan.

[0312] 2) Input basic data:

[0313] As mentioned earlier, input the basic parameters of the seawater desalination plant. Among them, the electricity purchase / sale price is shown in Table 1; the wind power output during the winter and summer seasons within the dispatch cycle is shown in Table 2; the seawater parameters are shown in Table 3; and the wind and solar power output is shown in the appendix. Figure 5 As shown.

[0314] Table 1 Electricity Purchase / Sale Prices

[0315]

[0316] Table 2 Wind power output during the winter and summer seasons within the scheduling cycle.

[0317]

[0318]

[0319] Table 3 Seawater Parameters

[0320] parameter value Seawater concentration (mg / L) 3E4

[0321] 3) Model building and solution

[0322] As mentioned above, models of each piece of equipment in the seawater desalination plant are established, with Equation (37) as the objective function, and then the Gurobi solver is called in Yalmip to solve the problem and obtain the optimization results.

[0323] 4) Experimental Results

[0324] Two calculation examples are used to analyze the schemes of seawater desalination plants, verifying the effectiveness and superiority of the present invention. On one hand, calculation example 1 is set up as follows:

[0325] Comparison of winter and summer scheduling of reverse osmosis desalination plants;

[0326] On the other hand, to verify the effect of pressure-delayed permeation, Example 2 is as follows:

[0327] Comparison of winter scheduling of reverse osmosis desalination plants and winter scheduling of reverse osmosis-pressure delayed osmosis desalination plants.

[0328] (1) Calculation example 1

[0329] First, we analyze two scheduling schemes for reverse osmosis desalination plants in two different seasons. Table 4 below shows the various costs and energy consumption of the seawater desalination plant under the two schemes.

[0330] Table 4 Cost and Energy Consumption of Example 1

[0331]

[0332]

[0333] A comprehensive comparison reveals that the costs of the high-pressure pump and the intake pump are the same in winter and summer because the water production is the same, resulting in the same total water flow for both pumps. However, wind power is significantly less in summer than in winter, leading to the desalination plant purchasing more electricity from the distribution network and higher interaction costs. In both seasons, the plant purchases electricity and charges its energy storage system when electricity prices are low, then discharges it when prices are high to reduce the cost of electricity purchases.

[0334] From the perspective of energy consumption comparison, the main reason is that the seawater temperature varies in different seasons. The temperature in summer is higher than in winter, which leads to an increase in the energy consumption of the high-pressure pump in summer in order to maintain a stable water flow rate.

[0335] In summary, the numerical examples verified the correctness and effectiveness of the reverse osmosis seawater desalination plant operation scheduling method proposed in this invention, which considers temperature and concentration.

[0336] (2) Calculation example 2

[0337] To further verify the pressure-delayed permeation model of this invention, the scheduling results of a reverse osmosis desalination plant and a reverse osmosis-pressure-delayed permeation desalination plant were compared under winter conditions. Table 5 below shows the various costs and energy consumption of the seawater desalination plant under the two schemes.

[0338] Table 5 Cost and Energy Consumption of Example 2

[0339] plan reverse osmosis Reverse osmosis - pressure delayed osmosis Total cost / yuan 31398 30253 High-pressure pump operation and maintenance cost (RMB) 13383 13383 High-pressure pump start-up and shutdown cost (RMB) 0 0 Water intake pump operation and maintenance cost / yuan 8579 10724 Water pump start-up and shutdown cost (RMB) 0 0 Water turbine operation and maintenance cost / yuan 0 2230 Turbine start-up and shutdown cost (yuan) 0 0 Interaction cost / yuan 4840 3522 Energy storage operation and maintenance cost (RMB) 128 23 Wind turbine operation and maintenance cost / yuan 369 369 Wind abandonment penalty / yuan 0 0 Emissions penalty / yuan 4099 0 Desalination plant energy consumption / kWh 20157 21784 Hydropower generation capacity / kWh 0 3340

[0340] As shown in Table 5, the total cost of a reverse osmosis-pressure delayed permeation desalination plant is lower than that of a reverse osmosis desalination plant. This is because pressure delayed permeation can recover energy from the concentrated brine, reducing interaction costs, and the treatment of concentrated brine reduces discharge penalties. The turbine power generation accounts for 15.33% of the desalination plant's energy consumption, demonstrating a significant energy-saving effect.

[0341] contrast Figure 6 and Figure 7 In both scenarios, the desalination plants purchase large amounts of electricity during the 1-7 hour period when electricity prices are low, thus increasing freshwater production. Conversely, they cease purchasing electricity during the 10-12 and 17-21 hour periods when prices are high, relying entirely on wind power for water production to reduce costs. Both scenarios also utilize energy storage to shift peak electricity demand and lower electricity purchase costs. Figure 7 During each period, the turbine collects energy through pressure-delayed infiltration to reduce energy consumption.

[0342] In summary, this invention discloses a scheduling method for a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage. This invention fully leverages the flexibility of seawater desalination plants, enabling stable loads and peak shaving / valley filling, and improves the economic efficiency and environmental friendliness of the desalination plant through pressure-delayed permeation.

Claims

1. A method for scheduling a reverse osmosis seawater desalination plant that takes into account the pressure-delayed permeation stage, characterized in that, Includes the following steps: 1) Obtain the basic parameters of the seawater desalination plant; 2) Based on the basic parameters, the seawater desalination process is modeled to obtain the equipment unit model of the seawater desalination plant; 3) Based on the basic model of the equipment unit model of the seawater desalination plant, establish the operating constraints of the seawater desalination plant; 4) Combining the equipment unit model of the seawater desalination plant and the operating constraints of the seawater desalination plant, construct the overall scheduling model of the seawater desalination plant; 5) Solve the overall scheduling model of the seawater desalination plant to obtain the optimal scheduling scheme for the seawater desalination plant; The seawater desalination plant equipment unit model includes a water intake pump model, a reverse osmosis high-pressure pump unit model, a pressure delayed osmosis unit model, and an energy storage device model. The water intake pump model is shown below: Where the subscript t represents the time period t; P t In and These represent the water intake pump power and water intake flow rate for the t-th time period, respectively; H In The pump head is given by ρ; ρ and g are the density of water and the acceleration due to gravity, respectively; η is the pump head. In To improve the operating efficiency of the water intake pump; The reverse osmosis high-pressure pump unit model is shown below: p FD,t =kC FD,t ,p BR,t =kC BR,t ,p PR,t =κC PR,t (7) Among them, P t RO Power of the high-pressure pump for the reverse osmosis module; The seawater flow rate for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO For the operating efficiency of the high-pressure pump of the reverse osmosis module; q PR,t K represents the product's permeate flow rate. RO S RO These are the permeability coefficient and membrane area of ​​the permeable membrane, respectively. T is the feed water temperature coefficient; N is the water temperature; and N is the number of reverse osmosis membranes. For the hydraulic differential pressure of the reverse osmosis module; p BR,t and p PR,t The water pressures of the concentrated brine and the product water are respectively; Δπ t π represents the osmotic pressure difference of the reverse osmosis module. FD,t π BR,t and π PR,t These are the osmotic pressures of the feed seawater, concentrated brine, and product water, respectively. C is the concentration polarization coefficient; FD,t C BR,t and C PR,t q represents the concentrations of feed seawater, concentrated brine, and product water, respectively; k is the proportionality coefficient between solution osmotic pressure and solution concentration; q BR,t R is the concentrated brine flow rate; R is the reverse osmosis recovery rate. The pressure-delayed infiltration unit model includes equations for calculating water flow rate, power generation, hydraulic pressure difference in the pressure-delayed infiltration module, and power consumption of the high-pressure pump in the pressure-delayed infiltration module. The equation for calculating water flow rate in the pressure-delayed permeation module is shown below: Where, q w,t This refers to the flow rate of water passing through the semipermeable membrane. This refers to the temperature coefficient of concentrated brine in the concentrated brine tank. The pressure delay permeation module has a hydraulic differential; A, k, S, D, and β are the membrane's permeability coefficient, mass transfer coefficient, membrane structural parameters, volume diffusion coefficient, and solute permeability, respectively. The equation for calculating the power generation of pressure-delayed infiltration is shown below: Among them, P t TUR It is the power generation capacity of the water turbine; η TUR For the operating efficiency of the water turbine; The equation for calculating the hydraulic differential pressure in the pressure-delayed permeation module is shown below: in, p FS,t and p w,t These are hydraulic pressure for pressurized high-salinity extraction solution, hydraulic pressure for low-salinity feed solution, and hydraulic pressure for water passing through a semi-permeable membrane; The power consumption calculation equation for the high-pressure pump of the pressure-delayed permeation module is shown below: Among them, P t PRO Power consumption of the high-pressure pump in the reverse osmosis module; For the concentrated brine flow rate entering the pressure-delayed permeation module; η PRO To improve the operating efficiency of the high-pressure pump in the reverse osmosis module; The energy storage device model includes a water storage tank model and an electric energy storage device model; The reservoir model is shown below: in, and The water levels in the clear water tank, product water tank, and concentrated brine tank during time period t are respectively. and The water levels in the clear water tank and the product water tank at time t-1 are respectively; r Pre This represents the ratio of pretreated seawater to feed water flow rate. This refers to the water flow rate from the product's water tank. A represents the seawater flow rate for the pressure-delayed permeation module. CLT A PRT and A BRT The bottom areas of the clear water tank, product water tank, and concentrated brine tank are respectively; T T The total number of time periods in a scheduling cycle; and These represent the initial and final values ​​of the water level in the clear water reservoir during the scheduling cycle; and These represent the initial and final values ​​of the product pool water level during the scheduling cycle; and These represent the initial and final values ​​of the water level in the concentrated brine pool during the scheduling cycle; h CLT These are the upper and lower limits of the water level in the clear water pool; h PRT These are the upper and lower limits of the water level in the product pool, respectively. h BRT These represent the upper and lower limits of the water level in the concentrated brine tank, respectively; q t Δt represents the total freshwater production of all reverse osmosis units during time period t; Δt is the scheduling time interval. The concentration and temperature balance of the solution in the reservoir are shown below: Among them, C BRT,t C BRT,t-1 These represent the concentrations of concentrated brine in the brine tank at time periods t and t-1, respectively. Let C be the water intake flow in the t-th time period; In,t T represents the water concentration. In,t T BR,t The water intake temperature of the water pump and the temperature of the concentrated brine; The concentration balance of the pressure-delayed osmosis module in the reservoir is shown below: in, The concentration of the discharged water; The energy storage model is shown below: Among them, P t CH and P t DCH These represent the charging and discharging power of the energy storage, respectively; η CH and η DCH These refer to the charging and discharging efficiencies of the energy storage system. The energy stored at time t and time t-1 is the energy stored during the time period t. and These are 0-1 variables representing the charging and discharging states of electrical energy storage; and These represent the initial and final values ​​of the energy storage capacity within the dispatch cycle; P CH , These are the lower and upper limits of the charging power for electric energy storage, respectively. P DCH , These represent the lower and upper limits of the energy storage discharge power, respectively; Δt is the scheduling time interval. E BE , These represent the lower and upper limits of the energy storage capacity, respectively.

2. The method for scheduling a reverse osmosis seawater desalination plant considering pressure-delayed permeation as described in claim 1, characterized in that, The basic parameters of a seawater desalination plant include the parameters of each piece of equipment, time-of-use electricity price, freshwater load, wind power forecast, seawater concentration, and seawater temperature.

3. The method for scheduling a reverse osmosis seawater desalination plant considering the pressure-delayed permeation stage according to claim 1, characterized in that, The operational constraints of the seawater desalination plant include intake pump flow constraints, intake pump power constraints, intake pump start-stop constraints, linear energy consumption constraints of the high-pressure pump in the reverse osmosis module, flow constraints of the high-pressure pump in the reverse osmosis module and the pressure delayed osmosis module, high-pressure pump power constraints, high-pressure pump operating pressure constraints, high-pressure pump start-stop frequency constraints, total water production constraints of the reverse osmosis unit, turbine power constraints, turbine start-stop constraints, wind turbine operation constraints, and power balance constraints.

4. The method for scheduling a reverse osmosis seawater desalination plant considering pressure-delayed permeation as described in claim 3, characterized in that, The flow constraints of the water intake pump are as follows: in, This refers to the water intake pump flow rate; A 0-1 variable representing the working state of the water intake pump; and q In These are the upper and lower limits of the water intake pump flow rate, respectively. The power constraints of the water intake pump are as follows: Among them, P In,UP and P In,DN These are the upper and lower power limits for the water intake pump, respectively; P t In , The power of the water pump during time period t and time period t-1; P t In This refers to the upper and lower limits of the water pump power. These are 0-1 variables characterizing the operating status of the water intake pumps during time periods t and t-1. The start / stop constraints for the water intake pump are as follows: Among them, C In 、F t In These are the single start-up and shutdown costs of the water intake pump and its total start-up and shutdown costs over time period t; M In This refers to the maximum number of times the water intake pump can be started and stopped within the scheduling cycle. A 0-1 variable representing the operating status of the water intake pump during time period t+1; The flow constraints of the high-pressure pumps in the reverse osmosis module and the pressure-delayed permeation module are shown below: in, The seawater flow rate for the reverse osmosis module; A 0-1 variable representing the operating state of the high-pressure pump in the reverse osmosis module; and These are the upper and lower limits of the flow rate of the high-pressure pump in the reverse osmosis module, respectively. The seawater flow rate for the pressure-delayed permeation module; 0-1 variables characterizing the operating state of the high-pressure pump in the pressure-delayed permeation module; and These are the upper and lower limits of the high-pressure pump flow rate for the pressure-delayed permeation module, respectively. The linear constraint on the energy consumption of the high-pressure pump in the reverse osmosis module is shown below: in, P represents the upper and lower limits of the operating pressure of the reverse osmosis module. t RO Power of the high-pressure pump for the reverse osmosis module; η is the pressure applied to the feed seawater by the high-pressure pump; RO To improve the operating efficiency of the high-pressure pump in the reverse osmosis module; This refers to the output power of the high-pressure pump in the reverse osmosis module. The power constraints of the high-pressure pumps in the reverse osmosis module and the pressure delayed osmosis module are shown below: Among them, P RO,UP and P RO,DN These represent the upper and lower power limits of the high-pressure pump in the reverse osmosis module, respectively; P t RO , The power of the high-pressure pump of the reverse osmosis module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the reverse osmosis module; P is a 0-1 variable characterizing the operating status of the high-pressure pump of the reverse osmosis module during time period t and t-1. PRO,UP and P PRO,DN These represent the upper and lower power limits of the high-pressure pump in the pressure-delayed permeation module, respectively; P t PRO , The power of the high-pressure pump in the pressure-delayed permeation module during time period t and time period t-1; The upper and lower limits of the high-pressure pump power for the pressure-delayed permeation module; The 0-1 variables characterize the operating status of the high-pressure pump in the pressure-delayed permeation module during time period t and t-1. The operating pressure constraints of the high-pressure pumps for the reverse osmosis module and the pressure-delayed osmosis module are as follows: in, The operating pressure of the reverse osmosis unit during time period t and time period t-1; This represents the upper and lower limits of the operating pressure of the reverse osmosis module; p RO,UP and p RO,DN This refers to the upper limit of the increase and decrease in operating pressure of the reverse osmosis module per unit time period; Δ p RO These are the upper and lower limits of the pressure difference in the reverse osmosis module; The working pressure of the pressure-delayed permeation unit during time period t and time period t-1; p represents the upper and lower limits of the operating pressure of the pressure-delayed permeation module. PRO,UP and p PRO,DN The upper limit of the pressure increment and decrement per unit time period for the pressure delay permeation module; Δπ t This refers to the osmotic pressure difference of the reverse osmosis module; Pressure difference for the reverse osmosis module; The constraints on the number of start-stop cycles of the high-pressure pump are as follows: Among them, M RO M represents the maximum permissible number of start-stop cycles for the high-pressure pump of the reverse osmosis module within the scheduling cycle. PRO This represents the maximum permissible number of start-stop cycles for the high-pressure pump in the pressure delay permeation module within the scheduling cycle. The total permeate capacity constraint of the reverse osmosis unit is shown below: Among them, S RO Δt is the lower limit of freshwater production within the scheduling cycle; q is the scheduling time interval; Δt is the lower limit of freshwater production within the scheduling cycle. PR,t The product's permeate water flow rate; The turbine flow constraints are shown below: Where, q w,t The turbine flow rate; A 0-1 variable characterizing the operating state of the water turbine; and q In These are the upper and lower limits of the turbine's flow rate, respectively. q w , These are the lower and upper limits of the turbine's flow rate; The power constraints of the water turbine are as follows: Among them, P TUR,UP and P TUR,DN These represent the upper and lower power limits for the turbine's uphill and downhill travel, respectively; P t TUR , This represents the power output of the turbine during time interval t and time interval t-1. P t TUR These are the upper and lower limits of the turbine's power output; These are 0-1 variables characterizing the operating status of the turbine during time period t and t-1. The turbine start-up and shutdown constraints are as follows: Among them, M TUR This represents the maximum number of times the turbine can be started and stopped within the scheduling cycle. The operating constraints of wind turbine units are as follows: 0≤P t WAG ≤P t WG (35) Among them, P t WG and P t WAG These are the predicted power and reduced power of the wind turbine units in the desalination plant, respectively. The power balance constraints are as follows: Among them, P t P2D The electricity purchased by the desalination plant from the distribution network; P t D2P To supply the electricity sold by the desalination plant to the power distribution network; To limit the interaction power between the desalination plant and the distribution network; P t RO P represents the power of the high-pressure pump in the reverse osmosis module. t In P is the power of the water intake pump in the t-th time period; t CH and P t DCH These represent the charging and discharging power of the energy storage system; P t PRO Power consumption of the high-pressure pump in the reverse osmosis module; P t TUR It refers to the power generation capacity of the water turbine.

5. The method for scheduling a reverse osmosis seawater desalination plant considering pressure-delayed permeation as described in claim 1, characterized in that, The objective function of the overall scheduling model for a seawater desalination plant is shown below: minC=C OP +C SU +C EN +C BE +C WG +C AW +C ENV (37) Among them, T T C represents the number of time periods in the scheduling cycle; C represents the total operating cost of the desalination plant. For equipment operation and maintenance costs, For equipment start-up and shutdown costs, To mitigate the power interaction costs between power plants and distribution networks, For the operation and maintenance costs of energy storage, For wind turbine operation and maintenance costs, As punishment for abandoning the wind, Punishment for discharging concentrated brine.

6. The method for scheduling a reverse osmosis seawater desalination plant considering the pressure-delayed permeation stage according to claim 5, characterized in that, Equipment maintenance costs Equipment start-up and shutdown costs Power interaction cost between desalination plant and power distribution network Energy storage operation and maintenance costs Wind turbine operation and maintenance costs wind abandonment punishment Discharging concentrated brine penalty As shown below: in and These are the operation and maintenance cost coefficients for the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficients for the high-pressure pump of the pressure-delayed osmosis module, and the operation and maintenance cost coefficients for the turbine. and These are the costs for a single start-up and shutdown of the high-pressure pump in the reverse osmosis module, the cost for a single start-up and shutdown of the high-pressure pump in the pressure-delayed osmosis module, and the cost for a single start-up and shutdown of the turbine. These are the unit prices for electricity purchased / sold by the desalination plant from the power distribution network; This is the coefficient for the operation and maintenance costs of energy storage. This is the coefficient for wind turbine operation and maintenance costs; This is the wind curtailment penalty coefficient; C is the environmental pollution penalty coefficient. ST The standard concentration for seawater discharge; The concentration of the discharged water.

7. A method for scheduling a reverse osmosis seawater desalination plant considering a pressure-delayed permeation stage, as described in claim 4, is characterized in that... The constraints of the overall scheduling model of the seawater desalination plant are the operating constraints of the seawater desalination plant (20)-(36).

8. A method for scheduling a reverse osmosis seawater desalination plant considering a pressure-delayed permeation stage, as described in claim 1, is characterized in that... Tools for solving the overall scheduling model of a seawater desalination plant include the Gurobi solver.

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