Reverse osmosis seawater desalination plant scheduling method considering pressure delay osmosis link

Abstract

The invention discloses a reverse osmosis seawater desalination plant scheduling method considering a pressure delay osmosis link. The method comprises the following steps: 1) acquiring basic parameters of a seawater desalination plant; 2) based on the basic parameters, modeling a seawater desalination process to obtain a seawater desalination plant equipment unit model; 3) based on the basic model of the equipment unit model of the seawater desalination plant, establishing operation constraint conditions of the seawater desalination plant; 4) combining the seawater desalination plant equipment unit model and the seawater desalination plant operation constraint conditions to construct a seawater desalination plant overall scheduling model; and 5) solving the overall dispatching model of the seawater desalination plant to obtain an optimized dispatching scheme of the seawater desalination plant. According to the reverse osmosis seawater desalination plant scheduling method considering the pressure delay osmosis link, a more efficient and environment-friendly seawater desalination process can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of integrated energy systems, and in particular to a reverse osmosis seawater desalination plant scheduling method taking into account a pressure delayed osmosis link. Background Art

[0002] About 40% of the world's population is facing the severe challenge of fresh water shortage. Against this background, seawater desalination technology has developed rapidly in countries with scarce water resources. Reverse osmosis technology is the most widely used seawater desalination method, although its energy consumption per ton of water has been reduced to 3 ～ 5kWh, but energy costs still account for about 40% of the total cost, indicating that the technology still has the problem of high energy consumption. In addition, the concentrated brine produced during the desalination process contains a large amount of chemical elements. If it is directly discharged, it will have a serious impact on the offshore environment and marine ecosystem.

[0003] In order to reduce the energy consumption of reverse osmosis desalination technology, researchers have found that the salinity difference in concentrated brine can be recycled. Pressure-delayed osmosis technology applies pressure on the high-concentration solution side to delay the osmosis of water molecules from low-concentration solution to high-concentration solution, thereby forming a larger hydraulic pressure on the high-concentration solution side to drive the turbine to generate electricity. This technology can not only convert the chemical energy in salt water into electrical energy for recycling, reducing the energy consumption of seawater desalination, but also reduce the pollution of high-concentration salt water to the ocean.

[0004] However, most of the current research literature on desalination plants focuses on the description of the reverse osmosis process, and few studies have made detailed descriptions of desalination plants that combine reverse osmosis with pressure delayed osmosis. At the same time, existing studies often ignore the impact of seawater temperature and concentration on energy consumption when exploring the desalination process. Summary of the invention

[0005] The object of the present invention is to provide a method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link, comprising the following steps:

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

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

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

[0009] 4) Combine the desalination plant equipment unit model and the desalination plant operation constraints to build the overall scheduling model of the desalination plant;

[0010] 5) Solve the overall scheduling model of the seawater desalination plant and obtain the optimal scheduling plan of the seawater desalination plant.

[0011] Furthermore, the basic parameters of the desalination plant include parameters of various equipment in the desalination plant, time-of-use electricity purchase / sale price, fresh water load, predicted wind power, seawater concentration, and seawater temperature.

[0012] Furthermore, the 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] Further, the water intake pump model is as follows:

[0014]

[0015] Wherein, the subscript t represents the period t; and are the water pump power and water flow in the tth period respectively; H In is the head of the water pump; ρ and g are the density of water and the acceleration of gravity respectively; η In The efficiency of water pump operation;

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

[0017]

[0018] in, is the high pressure pump power of the reverse osmosis module; Feed seawater flow rate for reverse osmosis module; The pressure applied by the high-pressure pump to the feed seawater; η RO is the operating efficiency of the high-pressure pump of the reverse osmosis module; q PR,t K is the product permeate flow rate; RO , S RO are the permeability coefficient and membrane area of ​​the permeable membrane respectively; is the feed water temperature coefficient; T is the water temperature; N is the number of reverse osmosis membranes; is the hydraulic pressure difference of the reverse osmosis module; p BR,t and p PR,t are the water pressures of concentrated brine and product water respectively; Δπ t is the osmotic pressure difference of the reverse osmosis module; π FD,t , π BR,t and π PR,t are the osmotic pressures of feed seawater, brine and product water, respectively; is the concentration polarization coefficient; C FD,t , C BR,t and C PR,t are the concentrations of feed seawater, concentrated brine and product water respectively; κ is the proportional coefficient between solution osmotic pressure and solution concentration. BR,t is the brine flow rate; R is the reverse osmosis recovery rate;

[0019] The pressure-delayed osmosis unit model includes a water flow calculation equation, a pressure-delayed osmosis power generation calculation equation, a pressure-delayed osmosis module hydraulic pressure difference calculation equation, and a pressure-delayed osmosis module high-pressure pump power consumption calculation equation;

[0020] The water flow calculation equation in the pressure delayed permeation module is as follows:

[0021]

[0022] Among them, q w,t is the water flow rate through the semipermeable membrane; is the temperature coefficient of concentrated brine in the concentrated brine pool; is the hydraulic pressure difference of the pressure-delayed osmosis module; A, k, S, D, and β are the membrane permeability coefficient, mass transfer coefficient, membrane structure parameter, volume diffusion coefficient, and solute permeability, respectively;

[0023] The calculation equation of pressure-delayed osmosis power generation is as follows:

[0024]

[0025] in, is the turbine power generation; η TUR is the turbine operating efficiency;

[0026] The calculation equation of the hydraulic pressure difference of the pressure delayed permeation module is as follows:

[0027]

[0028] in, p FS,t and p w,t They are the hydraulic pressure of the pressurized high-salinity extraction solution, the hydraulic pressure of the low-salinity feed solution, and the hydraulic pressure of water passing through the semipermeable membrane;

[0029] The power consumption calculation equation of the high-pressure pump of the pressure delayed permeation module is as follows:

[0030]

[0031] in, The power consumption of the high pressure pump of the reverse osmosis module; is the concentrated brine flow rate entering the pressure delayed osmosis module; η PRO The operating efficiency of the high-pressure pump of the reverse osmosis module;

[0032] The energy storage device includes a water reservoir model and an electrical energy storage device model;

[0033] The reservoir model is as follows:

[0034]

[0035] in, and are the water levels of the clean water pool, product water pool and concentrated brine pool during period t respectively; and are the water levels of the clean water tank and the product water tank at time t-1; r Pre is the ratio of the flow rate of pretreated seawater to feed water; The water outflow rate of the product pool; A is the feed seawater flow rate of the pressure delayed osmosis module; CLT , A PRT and A BRT are the bottom areas of the clean water pool, product water pool and concentrated brine pool respectively; T T is the total number of time slots in a scheduling cycle; and They are the initial and final values ​​of the water level in the clear water tank during the scheduling period; and They are the initial and final values ​​of the product pool water level in the scheduling cycle respectively; and They are the initial and final values ​​of the water level in the concentrated brine pool during the scheduling period; h CLT They are the upper and lower limits of the water level in the clear water tank respectively; h PRT They are the upper and lower limits of the product water pool water level respectively; h BRT are the upper and lower limits of the brine pool water level respectively; q t is the total freshwater production of all reverse osmosis units during period t; Δt is the scheduling time interval;

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

[0037]

[0038] Among them, C BRT,t , C BRT,t-1 are the concentrations of the concentrated brine in the concentrated brine pool at time periods t and t-1 respectively; is the water intake flow in the tth period; C In,t is the water concentration; T In,t , T BR,t The water intake temperature of the water intake pump and the concentrated brine temperature;

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

[0040]

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

[0042] The electric energy storage model is as follows:

[0043]

[0044] in, and are the charging and discharging power of the energy storage respectively; η CH and η DCH are the charging and discharging efficiency of electric energy storage respectively; is the energy storage capacity at time t-1 during period t; and are 0-1 variables representing the charging and discharging states of the energy storage; and They are the initial and final values ​​of the electric energy storage capacity in the dispatching cycle respectively; P CH , are the lower and upper limits of the electric energy storage charging power respectively; P DCH , are the lower and upper limits of the energy storage discharge power respectively; Δt is the scheduling time interval; E BE , They are the lower and upper limits of the electric energy storage capacity respectively.

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

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

[0047]

[0048] in, is the water intake pump flow; is a 0-1 variable representing the working status of the water intake pump; and q In They are the upper and lower limits of the water intake pump flow rate respectively;

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

[0050]

[0051] Among them, P In,UP and P In,DN They are the upper and lower climbing power limits of the water intake pump respectively; is the power of the water intake pump in period t and period t-1; The upper and lower limits of the water pump power; is a 0-1 variable representing the operating status of the water intake pump during period t and period t-1;

[0052] The start and stop constraints of the water intake pump are as follows:

[0053]

[0054] Among them, C In , are the single start-stop cost of the water pump and the total start-stop cost in time period t; M In The maximum allowed start and stop times of the water intake pump within the scheduling cycle; is a 0-1 variable representing the operating status of the water intake pump during period t+1;

[0055] The high pressure pump flow constraints for the reverse osmosis module and the pressure delayed osmosis module are as follows:

[0056]

[0057] in, Feed seawater flow rate for reverse osmosis module; A 0-1 variable representing the working state of the high-pressure pump of the reverse osmosis module; and They are the upper and lower limits of the flow rate of the high-pressure pump of the reverse osmosis module respectively; Feed seawater flow rate for the pressure delayed osmosis module; is a 0-1 variable that characterizes the working state of the high-pressure pump of the pressure-delayed permeation module; and They are the upper and lower limits of the high-pressure pump flow rate of the pressure delayed osmosis module respectively.

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

[0059]

[0060] in, The upper and lower limits of the reverse osmosis module working pressure; is the high pressure pump power of the reverse osmosis module; The pressure applied by the high-pressure pump to the feed seawater; η RO The operating efficiency of the high-pressure pump of the reverse osmosis module; Output power for the high pressure pump of 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 as follows:

[0062]

[0063] Among them, P RO,UP and P RO,DN They are respectively the upper and lower climbing power limits of the high-pressure pump of the reverse osmosis module; is the power of the high-pressure pump of the reverse osmosis module in time period t and time period t-1; The upper and lower limits of the high-pressure pump power of the reverse osmosis module; is a 0-1 variable representing the operating status of the high-pressure pump of the reverse osmosis module during period t and period t-1; PRO,UP and P PRO,DN They are respectively the upper and lower climbing power limits of the high-pressure pump of the pressure delayed permeation module; is the power of the high-pressure pump of the pressure delayed permeation module in time periods t and t-1; The upper and lower limits of the high-pressure pump power of the pressure delayed permeation module; is a 0-1 variable representing the operating state of the high-pressure pump of the pressure-delayed permeation module during period t and period t-1;

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

[0065]

[0066] in, is the working pressure of the reverse osmosis unit in period t and period t-1; is the upper and lower limits of the reverse osmosis module working pressure; p RO,UP and p RO,DN The upper limit of the increment and decrement of the working pressure of the reverse osmosis module per unit time period; Δ p RO The upper and lower limits of the pressure difference of the reverse osmosis module; is the working pressure of the pressure delayed permeation unit at time period t and time period t-1; is the upper and lower limits of the working pressure of the pressure delayed permeation module; p PRO,UP and p PRO,DN Δπ is the upper limit of the increment and decrement of the working pressure of the pressure delayed penetration module per unit time period; t is the osmotic pressure difference of the reverse osmosis module; is the pressure difference of the reverse osmosis module;

[0067] The high-pressure pump start and stop times constraints are as follows:

[0068]

[0069] Among them, M RO M is the maximum allowed start and stop times of the high-pressure pump of the reverse osmosis module within the scheduling period; PRO The maximum allowed start and stop times of the high-pressure pump of the pressure-delayed permeation module within the scheduling period;

[0070] The total water production constraint of the reverse osmosis unit is as follows:

[0071]

[0072] Among them, S RO is the lower limit of freshwater production within the scheduling period; Δt is the scheduling time interval; q PR,t The water flow rate for product penetration;

[0073] The turbine flow constraints are as follows:

[0074]

[0075] Among them, q w,t is the turbine flow rate; is a 0-1 variable representing the working state of the turbine; and q In are the upper and lower limits of turbine flow respectively; q w , are the lower and upper limits of turbine flow;

[0076] The turbine power constraints are as follows:

[0077]

[0078] Among them, P TUR,UP and P TUR,DN They are respectively the climbing and descending power upper limits of the turbine; is the power of the turbine in period t and period t-1; are the upper and lower limits of turbine power; It is a 0-1 variable that characterizes the operating status of the turbine in period t and period t-1.

[0079] The turbine start and stop constraints are as follows:

[0080]

[0081] Among them, M TUR The maximum allowable start and stop times of the turbine within the dispatching period.

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

[0083]

[0084] in, and They are the predicted power and curtailed power of wind turbines in desalination plants;

[0085] The power balance constraints are as follows:

[0086]

[0087] in, The amount of electricity purchased from the distribution grid for the desalination plant; The amount of electricity sold to the distribution grid for the desalination plant; It is the interactive power limit between the desalination plant and the distribution network; is the high pressure pump power of the reverse osmosis module; is the water intake pump power in the tth period; and are the charging and discharging power of the electric energy storage respectively; The power consumption of the high pressure pump of the reverse osmosis module; is the power generated by the turbine.

[0088] Furthermore, the objective function of the overall scheduling model of the 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 is the number of scheduling period periods; C is the total operating cost of the desalination plant, Equipment operation and maintenance costs, is the equipment start-up and shutdown cost, To reduce the power interaction cost between the desalination plant and the distribution network, For the operation and maintenance cost of electric energy storage, is the wind turbine operation and maintenance cost, Punishment for abandoning the wind, Punishment for discharging brine.

[0091] Furthermore, equipment operation and maintenance costs Equipment start-up and shutdown costs Power interaction cost between desalination plant and distribution network Energy storage operation and maintenance costs Wind turbine operation and maintenance costs Wind abandonment penalty Brine discharge penalty As shown below:

[0092]

[0093] in and They are the operation and maintenance cost coefficient of the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficient of the high-pressure pump of the pressure delayed osmosis module and the operation and maintenance cost coefficient of the turbine; and They are the single start-stop cost of the high-pressure pump of the reverse osmosis module, the single start-stop cost of the high-pressure pump of the pressure delayed osmosis module and the single start-stop cost of the turbine; The unit prices of electricity purchased / sold by the desalination plant to the distribution network are respectively; is the operation and maintenance cost coefficient of electric energy storage; is the wind turbine operation and maintenance cost coefficient; is the wind abandonment penalty coefficient; is the environmental pollution penalty coefficient; C ST is the standard concentration for seawater discharge; is the concentration of discharged water.

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

[0095] Furthermore, the tool for solving the overall dispatch model of the desalination plant includes the Gurobi solver.

[0096] The technical effect of the present invention is unquestionable. The present invention provides a reverse osmosis seawater desalination plant scheduling method taking into account the pressure delayed osmosis link, which can achieve a more efficient and environmentally friendly seawater desalination process. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 The figure is a flowchart of 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 The present invention is a flow chart of a reverse osmosis-pressure delayed osmosis seawater desalination plant.

[0100] Figure 4 This is a chart of sea water temperature in winter and summer.

[0101] Figure 5 This is the water load prediction diagram.

[0102] Figure 6 The results of reverse osmosis desalination plant scheduling in winter.

[0103] Figure 7 The results of the reverse osmosis-pressure delayed osmosis desalination plant scheduling in winter. DETAILED DESCRIPTION

[0104] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0105] Embodiment 1:

[0106] See also Figures 1 to 7 A method for scheduling a reverse osmosis desalination plant taking into account a pressure delayed osmosis link comprises the following steps:

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

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

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

[0110] 4) Combine the desalination plant equipment unit model and the desalination plant operation constraints to build the overall scheduling model of the desalination plant;

[0111] 5) Solve the overall scheduling model of the seawater desalination plant and obtain the optimal scheduling plan of the seawater desalination plant.

[0112] Embodiment 2:

[0113] A method for scheduling a reverse osmosis desalination plant taking into account a pressure delayed osmosis link, the technical content of which is the same as that of Example 1, and further, the basic parameters of the desalination plant include parameters of various equipment in the desalination plant, time-sharing electricity purchase / sale price, fresh water load, predicted wind power, seawater concentration, and seawater temperature.

[0114] Embodiment 3:

[0115] A method for scheduling a reverse osmosis desalination plant taking into account a pressure-delayed osmosis link, the technical content of which is the same as any one of Examples 1-2, and further, the 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] Embodiment 4:

[0117] A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link, the technical content of which is the same as any one of Embodiments 1-3, and further, the water intake pump model is as follows:

[0118]

[0119] Wherein, the subscript t represents the period t; and are the water pump power and water flow in the tth period respectively; H In is the head of the water pump; ρ and g are the density of water and the acceleration of gravity respectively; η In The efficiency of water pump operation;

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

[0121]

[0122] in, is the high pressure pump power of the reverse osmosis module; Feed seawater flow rate to the reverse osmosis module; The pressure applied by the high-pressure pump to the feed seawater; η RO is the operating efficiency of the high-pressure pump of the reverse osmosis module; q PR,t K is the product permeate flow rate; RO , S RO are the permeability coefficient and membrane area of ​​the permeable membrane respectively; is the feed water temperature coefficient; T is the water temperature; N is the number of reverse osmosis membranes; is the hydraulic pressure difference of the reverse osmosis module; p BR,t and p PR,t are the water pressures of brine and product water respectively; Δπ t is the osmotic pressure difference of the reverse osmosis module; π FD,t , π BR,t and π PR,t are the osmotic pressures of feed seawater, brine and product water, respectively; is the concentration polarization coefficient; C FD,t , C BR,t and C PR,t are the concentrations of feed seawater, concentrated brine and product water respectively; κ is the proportional coefficient between solution osmotic pressure and solution concentration. BR,t is the brine flow rate; R is the reverse osmosis recovery rate;

[0123] The pressure-delayed osmosis unit model includes a water flow calculation equation, a pressure-delayed osmosis power generation calculation equation, a pressure-delayed osmosis module hydraulic pressure difference calculation equation, and a pressure-delayed osmosis module high-pressure pump power consumption calculation equation;

[0124] The water flow calculation equation in the pressure delayed permeation module is as follows:

[0125]

[0126] Among them, q w,t is the water flow rate through the semipermeable membrane; is the temperature coefficient of concentrated brine in the concentrated brine pool; is the hydraulic pressure difference of the pressure-delayed osmosis module; A, k, S, D, and β are the membrane permeability coefficient, mass transfer coefficient, membrane structure parameter, volume diffusion coefficient, and solute permeability, respectively;

[0127] The calculation equation of pressure-delayed osmosis power generation is as follows:

[0128]

[0129] in, is the turbine power generation; η TUR is the turbine operating efficiency;

[0130] The calculation equation of the hydraulic pressure difference of the pressure delayed permeation module is as follows:

[0131]

[0132] in, p FS,t and p w,t They are the hydraulic pressure of the pressurized high-salinity extraction solution, the hydraulic pressure of the low-salinity feed solution, and the hydraulic pressure of water passing through the semipermeable membrane;

[0133] The power consumption calculation equation of the high-pressure pump of the pressure delayed permeation module is as follows:

[0134]

[0135] in, The power consumption of the high pressure pump of the reverse osmosis module; is the concentrated brine flow rate entering the pressure delayed osmosis module; η PRO The operating efficiency of the high-pressure pump of the reverse osmosis module;

[0136] The energy storage device includes a water reservoir model and an electrical energy storage device model;

[0137] The reservoir model is as follows:

[0138]

[0139] in, and are the water levels of the clean water pool, product water pool and concentrated brine pool during period t respectively; and are the water levels of the clean water tank and the product water tank at time t-1; r Pre is the ratio of the flow rate of pretreated seawater to feed water; The water outflow rate of the product pool; A is the feed seawater flow rate of the pressure delayed osmosis module; CLT , A PRT and A BRTare the bottom areas of the clean water pool, product water pool and concentrated brine pool respectively; T T is the total number of time slots in a scheduling cycle; and They are the initial and final values ​​of the water level in the clear water tank during the scheduling period; and They are the initial and final values ​​of the product pool water level in the scheduling cycle respectively; and They are the initial and final values ​​of the water level in the concentrated brine pool during the scheduling period; h CLT They are the upper and lower limits of the water level in the clear water tank respectively; h PRT They are the upper and lower limits of the product water pool water level respectively; h BRT are the upper and lower limits of the brine pool water level respectively; q t is the total freshwater production of all reverse osmosis units during period t; Δt is the scheduling time interval;

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

[0141]

[0142] Among them, C BRT,t , C BRT,t-1 are the concentrations of the concentrated brine in the concentrated brine pool at time periods t and t-1 respectively; is the water intake flow in the tth period; C In,t is the water concentration; T In,t , T BR,t The water intake temperature of the water intake pump and the concentrated brine temperature;

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

[0144]

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

[0146] The electric energy storage model is as follows:

[0147]

[0148] in, and are the charging and discharging power of the energy storage respectively; η CH and η DCH are the charging and discharging efficiency of electric energy storage respectively; is the energy storage capacity at time t-1 during period t; and are 0-1 variables representing the charging and discharging states of the energy storage; and They are the initial and final values ​​of the electric energy storage capacity in the dispatching cycle respectively; P CH , are the lower and upper limits of the electric energy storage charging power respectively; P DCH , are the lower and upper limits of the energy storage discharge power respectively; Δt is the scheduling time interval; E BE , They are the lower and upper limits of the electric energy storage capacity respectively.

[0149] Embodiment 5:

[0150] A method for scheduling a reverse osmosis desalination plant taking into account a pressure delayed osmosis link, the technical content of which is the same as any one of Examples 1-4, and further, the operating constraints of the desalination plant include water intake pump flow constraints, water intake pump power constraints, water intake pump start and stop constraints, linear constraints on energy consumption of reverse osmosis module high-pressure pumps, reverse osmosis module and pressure delayed osmosis module high-pressure pump flow constraints, high-pressure pump power constraints, high-pressure pump working pressure constraints, high-pressure pump start and stop times constraints, reverse osmosis unit total water production constraints, turbine power constraints, turbine start and stop constraints, wind turbine operation constraints, and power balance constraints.

[0151] Embodiment 6:

[0152] A method for scheduling a reverse osmosis desalination plant taking into account a pressure delayed osmosis link, the technical content of which is the same as any one of Embodiments 1-5, and further, the flow constraint of the water intake pump is as follows:

[0153]

[0154] in, is the water intake pump flow; is a 0-1 variable representing the working status of the water intake pump; and q In They are the upper and lower limits of the water intake pump flow rate respectively;

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

[0156]

[0157] Among them, P In,UP and P In,DN They are the upper and lower climbing power limits of the water intake pump respectively; is the power of the water intake pump in period t and period t-1; The upper and lower limits of the water pump power; is a 0-1 variable representing the operating status of the water intake pump during period t and period t-1;

[0158] The start and stop constraints of the water intake pump are as follows:

[0159]

[0160] Among them, C In , are the single start-stop cost of the water pump and the total start-stop cost in time period t; M In The maximum allowed start and stop times of the water intake pump within the scheduling cycle; is a 0-1 variable representing the operating status of the water intake pump during period t+1;

[0161] The high pressure pump flow constraints for the reverse osmosis module and the pressure delayed osmosis module are as follows:

[0162]

[0163] in, Feed seawater flow rate to the reverse osmosis module; A 0-1 variable representing the working state of the high-pressure pump of the reverse osmosis module; and They are the upper and lower limits of the flow rate of the high-pressure pump of the reverse osmosis module respectively; Feed seawater flow rate for the pressure delayed osmosis module; is a 0-1 variable that characterizes the working state of the high-pressure pump of the pressure-delayed permeation module; and They are the upper and lower limits of the high-pressure pump flow rate of the pressure delayed osmosis module respectively.

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

[0165]

[0166] in, The upper and lower limits of the reverse osmosis module working pressure; is the high pressure pump power of the reverse osmosis module; The pressure applied by the high-pressure pump to the feed seawater; η RO The operating efficiency of the high-pressure pump of the reverse osmosis module; Output power for the high pressure pump of 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 as follows:

[0168]

[0169]

[0170] Among them, P RO,UP and P RO,DN They are respectively the upper and lower climbing power limits of the high-pressure pump of the reverse osmosis module; is the power of the high-pressure pump of the reverse osmosis module in time period t and time period t-1; The upper and lower limits of the high-pressure pump power of the reverse osmosis module; is a 0-1 variable representing the operating status of the high-pressure pump of the reverse osmosis module during period t and period t-1; PRO,UP and P PRO,DN They are respectively the upper and lower climbing power limits of the high-pressure pump of the pressure delayed permeation module; is the power of the high-pressure pump of the pressure delayed permeation module in time periods t and t-1; The upper and lower limits of the high-pressure pump power of the pressure delayed permeation module; is a 0-1 variable representing the operating state of the high-pressure pump of the pressure-delayed permeation module during period t and period t-1;

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

[0172]

[0173] in, is the working pressure of the reverse osmosis unit in period t and period t-1; is the upper and lower limits of the reverse osmosis module working pressure; p RO,UP and p RO,DN The upper limit of the increment and decrement of the working pressure of the reverse osmosis module per unit time period; Δ p RO The upper and lower limits of the pressure difference of the reverse osmosis module; is the working pressure of the pressure delayed permeation unit at time period t and time period t-1; is the upper and lower limits of the working pressure of the pressure delayed permeation module; p PRO,UP and p PRO,DN Δπ is the upper limit of the increment and decrement of the working pressure of the pressure delayed penetration module per unit time period; t is the osmotic pressure difference of the reverse osmosis module; is the pressure difference of the reverse osmosis module;

[0174] The high-pressure pump start and stop times constraints are as follows:

[0175]

[0176]

[0177] Among them, M RO M is the maximum allowed start and stop times of the high-pressure pump of the reverse osmosis module within the scheduling period; PRO The maximum allowed start and stop times of the high-pressure pump of the pressure-delayed permeation module within the scheduling period;

[0178] The total water production constraint of the reverse osmosis unit is as follows:

[0179]

[0180] Among them, S RO is the lower limit of freshwater production within the scheduling period; Δt is the scheduling time interval; q PR,t The water flow rate for product penetration;

[0181] The turbine flow constraints are as follows:

[0182]

[0183] Among them, q w,t is the turbine flow rate; is a 0-1 variable representing the working state of the turbine; and q In are the upper and lower limits of turbine flow respectively; q w , are the lower and upper limits of turbine flow;

[0184] The turbine power constraints are as follows:

[0185]

[0186] Among them, P TUR,UP and P TUR,DN They are respectively the climbing and descending power upper limits of the turbine; is the power of the turbine in period t and period t-1; are the upper and lower limits of turbine power; It is a 0-1 variable that characterizes the operating status of the turbine in period t and period t-1.

[0187] The turbine start and stop constraints are as follows:

[0188]

[0189] Among them, M TUR The maximum allowable start and stop times of the turbine within the dispatching period.

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

[0191]

[0192] in, and They are the predicted power and curtailed power of wind turbines in desalination plants;

[0193] The power balance constraints are as follows:

[0194]

[0195] in, The amount of electricity purchased from the distribution grid for the desalination plant; The amount of electricity sold to the distribution grid for the desalination plant; It is the interactive power limit between the desalination plant and the distribution network; is the high pressure pump power of the reverse osmosis module; is the water intake pump power in the tth period; and are the charging and discharging power of the electric energy storage respectively; The power consumption of the high pressure pump of the reverse osmosis module; is the power generated by the turbine.

[0196] Embodiment 7:

[0197] A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link, the technical content of which is the same as any one of Embodiments 1-6, and further, the objective function of the overall scheduling model of the 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 is the number of scheduling period periods; C is the total operating cost of the desalination plant, Equipment operation and maintenance costs, is the equipment start-up and shutdown cost, To reduce the power interaction cost between the desalination plant and the distribution network, For the operation and maintenance cost of energy storage, is the wind turbine operation and maintenance cost, Punishment for abandoning the wind, Punishment for discharging brine.

[0200] Embodiment 8:

[0201] A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link, the technical content is the same as any one of embodiments 1-7, further, the equipment operation and maintenance cost Equipment start-up and shutdown costs Power interaction cost between desalination plant and distribution network Energy storage operation and maintenance costs Wind turbine operation and maintenance costs Wind abandonment penalty Brine discharge penalty As shown below:

[0202]

[0203] in and They are the operation and maintenance cost coefficient of the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficient of the high-pressure pump of the pressure delayed osmosis module and the operation and maintenance cost coefficient of the turbine; and They are the single start-stop cost of the high-pressure pump of the reverse osmosis module, the single start-stop cost of the high-pressure pump of the pressure delayed osmosis module and the single start-stop cost of the turbine; The unit prices of electricity purchased / sold by the desalination plant to the distribution network are respectively; is the operation and maintenance cost coefficient of electric energy storage; is the wind turbine operation and maintenance cost coefficient; is the wind abandonment penalty coefficient; is the environmental pollution penalty coefficient; C ST is the standard concentration for seawater discharge; is the concentration of discharged water.

[0204] Embodiment 9:

[0205] A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link, the technical content of which is the same as any one of Examples 1-8, and further, the constraints of the overall scheduling model of the desalination plant are the operating constraints of the desalination plant (20)-(36).

[0206] Embodiment 10:

[0207] A method for scheduling a reverse osmosis desalination plant taking into account a pressure delayed osmosis link, the technical content of which is the same as any one of embodiments 1-9. Furthermore, a tool for solving the overall scheduling model of the desalination plant includes a Gurobi solver.

[0208] Embodiment 11:

[0209] A method for scheduling a reverse osmosis desalination plant taking into account a pressure delayed osmosis link, the steps are as follows:

[0210] Enter the basic parameters of the desalination plant;

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

[0212] Based on the above basic model, the operating constraints of the desalination plant are established;

[0213] Solve the above-mentioned overall model of the seawater desalination plant and obtain the optimal scheduling plan of the seawater desalination plant.

[0214] The specific implementation steps are as follows:

[0215] Basic parameters:

[0216] The basic parameters of the desalination plant include equipment parameters, time-sharing electricity purchase / sale price, fresh water load, wind power forecast power, seawater concentration, seawater temperature, etc. Detailed parameters will be given in the following example.

[0217] Device Model:

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

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

[0220]

[0221] The subscript t represents the time period t; P Int and q Int are the water pump power and water flow in the tth period respectively; H In is the head of the water pump; ρ and g are the density of water and the acceleration of gravity respectively; η In is the water pump operating efficiency. To simplify the description, the time period subscript t of the variable will not be specifically explained below.

[0222] The energy consumption characteristics of the reverse osmosis module high pressure pump are as follows:

[0223]

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

[0225] The high-pressure pump flow calculation equation and its parameter variable definitions are as follows:

[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 is the product permeate flow rate; RO , A RO are the permeability coefficient and membrane area of ​​the permeable membrane respectively; is the feed water temperature coefficient; T is the water temperature; N is the number of reverse osmosis membranes; is the hydraulic pressure difference of the reverse osmosis module; p BR,t and p PR,t are the water pressures of concentrated brine and product water respectively; Δπ t is the osmotic pressure difference of the reverse osmosis module; π FD,t , π BR,t and π PR,t are the osmotic pressures of feed seawater, concentrated brine and product water respectively; C t F is the concentration polarization coefficient; C FD,t , C BR,t and C PR,t are the concentrations of feed seawater, brine and product water respectively; κ is the proportional coefficient of solution osmotic pressure and solution concentration.

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

[0231]

[0232] where q PR,t is the product water flow rate; q BR,t is the brine flow rate; R is the reverse osmosis recovery rate.

[0233] The water flow calculation equation in the pressure delayed permeation module is as follows:

[0234]

[0235] where q w,t is the water flow rate through the semipermeable membrane; is the temperature coefficient of concentrated brine in the concentrated brine pool; is the hydraulic difference of the pressure-delayed osmosis module; A, k, S, D, and β are the permeability coefficient, mass transfer coefficient, membrane structure parameters, volume diffusion coefficient, and solute permeability of the membrane, respectively.

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

[0237]

[0238] in is the turbine power generation; η TUR The operating efficiency of the turbine.

[0239] The hydraulic pressure difference of the pressure delayed permeation module is as follows:

[0240]

[0241] in p FS,t and p w,t They are the hydraulic pressure of the pressurized high-salinity extraction solution, the hydraulic pressure of the low-salinity feed solution, and the hydraulic pressure of water passing through the semipermeable membrane.

[0242] The power consumption of the high pressure pump of the pressure delayed osmosis module is as follows:

[0243]

[0244] in The power consumption of the high pressure pump of the reverse osmosis module; is the concentrated brine flow rate entering the pressure delayed osmosis module; η PRO The high pressure pump operating efficiency for the reverse osmosis module.

[0245] The energy storage device includes a water tank model and an electric energy storage device model, where the water tank model is as follows:

[0246]

[0247] in, and are the water levels of the clean water pool, product water pool and concentrated brine pool during period t respectively; and are the water levels of the clean water tank and the product water tank at time t-1; r Pre is the ratio of the flow rate of pretreated seawater to feed water; q Outt The water outflow rate of the product pool; A is the feed seawater flow rate of the pressure delayed osmosis module; CLT , A PRT and A BRT are the bottom areas of the clean water pool, product water pool and concentrated brine pool respectively; T T is the total number of time slots in a scheduling cycle; and They are the initial and final values ​​of the water level in the clear water tank during the scheduling period; and They are the initial and final values ​​of the product pool water level in the scheduling cycle respectively; and They are the initial and final values ​​of the water level in the concentrated brine pool during the scheduling period; h CLT They are the upper and lower limits of the water level in the clear water tank respectively; h PRTThey are the upper and lower limits of the product water pool water level respectively; h BRT are the upper and lower limits of the brine pool water level respectively; q t is the total freshwater production of all reverse osmosis units during period t.

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

[0249]

[0250] Among them C BRT,t , C BRT,t-1 are the concentrations of the brine in the brine pool at time periods t and t-1 respectively.

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

[0252]

[0253] in is the concentration of discharged water.

[0254] The electric energy storage model is as follows:

[0255]

[0256] in and are the charging and discharging power of the energy storage respectively; η CH and η DCH are the charging and discharging efficiency of electric energy storage respectively; is the energy storage capacity at time t-1 during period t; and are 0-1 variables representing the charging and discharging states of the energy storage; and They are the initial and final values ​​of the electric energy storage capacity in the dispatching cycle respectively; P CH , are the lower and upper limits of the electric energy storage charging power respectively; P DCH , are the lower and upper limits of the energy storage discharge power respectively; Δt is the scheduling time interval.

[0257] Constraints:

[0258] The operating constraints of the seawater desalination plant include water intake pump flow constraint, water intake pump power constraint, water intake pump start and stop constraint, reverse osmosis module and pressure delayed osmosis module high-pressure pump flow constraint, high-pressure pump power constraint, high-pressure pump working pressure constraint, high-pressure pump start and stop times constraint, reverse osmosis unit total water production constraint, turbine power constraint, turbine start and stop constraint, wind turbine operation constraint, power balance constraint, etc.

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

[0260]

[0261] in is the water intake pump flow; is a 0-1 variable representing the working status of the water intake pump; and q In They are the upper and lower limits of the water intake pump flow rate respectively.

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

[0263]

[0264] Where P In,UP and P In,DN They are the upper and lower climbing power limits of the water intake pump respectively; is the power of the water intake pump in period t and period t-1; The upper and lower limits of the water pump power; It is a 0-1 variable that represents the operating status of the water pump in period t and period t-1.

[0265] The start and stop constraints of the water intake pump are as follows:

[0266]

[0267] Among them C In , are the single start-stop cost of the water pump and the total start-stop cost in time period t; M In The maximum allowed start and stop times of the water intake pump within the scheduling cycle.

[0268] The high pressure pump flow constraints for the reverse osmosis module and the pressure delayed osmosis module are as follows:

[0269]

[0270] in Feed seawater flow rate for reverse osmosis module; A 0-1 variable representing the working state of the high-pressure pump of the reverse osmosis module; and They are the upper and lower limits of the flow rate of the high-pressure pump of the reverse osmosis module respectively; Feed seawater flow rate for the pressure delayed osmosis module; is a 0-1 variable that characterizes the working state of the high-pressure pump of the pressure-delayed permeation module; and They are the upper and lower limits of the high-pressure pump flow rate of the pressure delayed osmosis module respectively.

[0271] Processing the bilinear constraints of formula (2) yields:

[0272]

[0273] in The upper and lower limits of the reverse osmosis module working pressure are the same as those of equations (11) and (13).

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

[0275]

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

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

[0278]

[0279] In the formula, is the working pressure of the reverse osmosis unit in period t and period t-1; is the upper and lower limits of the reverse osmosis module working pressure; p RO,UP and p RO,DN The upper limit of the increment and decrement of the working pressure of the reverse osmosis module per unit time period; Δ p ROThe upper and lower limits of the pressure difference of the reverse osmosis module; is the working pressure of the pressure delayed permeation unit at time period t and time period t-1; is the upper and lower limits of the working pressure of the pressure delayed permeation module; p PRO,UP and p PRO,DN It is the upper limit of the working pressure increase and decrease per unit time period of the pressure delayed infiltration module.

[0280]

[0281] Among them C RO , are the single start-stop cost of the high-pressure pump of the reverse osmosis module and its total start-stop cost within time period t; M RO C is the maximum allowed start and stop times of the high-pressure pump of the reverse osmosis module within the scheduling period; PRO , are the single start-stop cost of the high-pressure pump of the pressure delayed osmosis module and its total start-stop cost within time period t; M PRO The maximum allowed start and stop times of the high-pressure pump of the pressure delayed permeation module within the scheduling period.

[0282] The total water production constraint of the reverse osmosis unit is as follows:

[0283]

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

[0285] The turbine flow constraints are as follows:

[0286]

[0287] where q w,t is the turbine flow rate; is a 0-1 variable representing the working state of the turbine; and q In are the upper and lower limits of turbine flow respectively.

[0288] The turbine power constraints are as follows:

[0289]

[0290] Where P TUR,UP and P TUR,DN They are respectively the climbing and descending power upper limits of the turbine; is the power of the turbine in period t and period t-1; are the upper and lower limits of turbine power; It is a 0-1 variable that characterizes the operating status of the turbine in period t and period t-1.

[0291] The turbine start and stop constraints are as follows:

[0292]

[0293] Among them C TUR , are the single start-stop cost of the turbine and the total start-stop cost in time period t; M TUR The maximum allowable start and stop times of the turbine within the dispatching period.

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

[0295]

[0296] in and They are the predicted power and curtailed power of wind turbines in desalination plants;

[0297] The power balance constraints are as follows:

[0298]

[0299] in The amount of electricity purchased from the distribution grid for the desalination plant; The amount of electricity sold to the distribution grid for the desalination plant; It is the interactive power limit between the desalination plant and the distribution network.

[0300] Model solution:

[0301] Based on the above desalination plant model, 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 is the number of scheduling period time periods (T T =24); C is the total operating cost of the desalination plant, Equipment operation and maintenance costs, is the equipment start-up and shutdown cost, To reduce the power interaction cost between the desalination plant and the distribution network, For the operation and maintenance cost of energy storage, is the wind turbine operation and maintenance cost, Punishment for abandoning the wind, Punishment for discharging brine.

[0304] The specific calculation of various costs and benefits is as follows:

[0305]

[0306] in and They are the operation and maintenance cost coefficient of the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficient of the high-pressure pump of the pressure delayed osmosis module and the operation and maintenance cost coefficient of the turbine; and They are the single start-stop cost of the high-pressure pump of the reverse osmosis module, the single start-stop cost of the high-pressure pump of the pressure delayed osmosis module and the single start-stop cost of the turbine; The unit prices of electricity purchased / sold by the desalination plant to the distribution network are respectively; is the operation and maintenance cost coefficient of electric energy storage; is the wind turbine operation and maintenance cost coefficient; is the wind abandonment penalty coefficient; is the environmental pollution penalty coefficient; C ST It is the standard concentration for seawater discharge.

[0307] In summary, the Gurobi solver is used to solve the model and obtain the optimization result.

[0308] Embodiment 12:

[0309] The verification of a reverse osmosis desalination plant scheduling method taking into account the pressure delayed osmosis link is as follows:

[0310] 1) Obtain the structural diagram of the desalination plant. Among them: the electric bus is connected to the power grid, electric energy storage, wind turbines and energy-consuming equipment of the desalination plant. The wind farm supplies energy to the desalination plant, and the distribution network sells electricity to the desalination plant, allowing the wind power of the desalination plant to be connected to the grid.

[0311] As attached Figure 3 As shown, the seawater first enters the clear water tank through the water intake pump for pretreatment. After flocculation, sedimentation and other treatments, a part of it enters the reverse osmosis unit for desalination treatment. The high-pressure pump of the reverse osmosis unit is pressurized to achieve salt-water separation, and the concentrated brine enters the concentrated brine tank; the desalinated fresh water enters the product water tank to supply water load; a part of the seawater and the concentrated brine enter 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 a clear water tank, a product water tank and a concentrated brine tank to achieve flexible regulation of the water production plan.

[0312] 2) Input basic data:

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

[0314] Table 1 Purchase / sale electricity prices

[0315]

[0316] Table 2 Wind power in winter and summer during the dispatch period

[0317]

[0318]

[0319] Table 3 Seawater parameters

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

[0321] 3) Model establishment and solution

[0322] As mentioned above, the models of each device in the desalination plant are established, and equation (37) is used as the objective function. Then, the Gurobi solver is called in Yalmip to solve and obtain the optimization result.

[0323] 4) Experimental results

[0324] The desalination plant scheme is analyzed from two examples to verify the effectiveness and superiority of the present invention. On the one hand, Example 1 is set as follows:

[0325] Comparison of winter reverse osmosis desalination plant scheduling with summer reverse osmosis desalination plant scheduling;

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

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

[0328] (1) Calculation example 1

[0329] First, two schemes for the scheduling of the reverse osmosis desalination plant in two seasons are analyzed. Table 4 below gives the various costs and energy consumption of the desalination plant under the two schemes.

[0330] Table 4 Cost and energy consumption of Example 1

[0331]

[0332]

[0333] A comprehensive comparison shows that the cost of high-pressure pumps and water intake pumps in winter and summer is the same because the water output is the same, resulting in the same total water flow of high-pressure pumps and water intake pumps. However, wind power in summer is significantly less than in winter, resulting in more electricity purchases from the distribution network by the desalination plant, resulting in higher interaction costs. In both seasons, electricity is purchased and charged to the energy storage when the electricity price is low, and discharged when the electricity price is high to reduce the cost of purchasing electricity.

[0334] From the perspective of energy consumption comparison, it is mainly because the seawater temperature is different in different seasons. The temperature in summer is higher than that in winter, which leads to the need to increase the energy consumption of the high-pressure pump in summer to maintain the stability of the water flow rate.

[0335] In summary, the correctness and effectiveness of the reverse osmosis seawater desalination plant operation scheduling considering temperature and concentration proposed in the present invention have been verified through examples.

[0336] (2) Calculation example 2

[0337] To further verify the pressure delayed osmosis model of the present invention, the scheduling results of the reverse osmosis desalination plant and the reverse osmosis-pressure delayed osmosis desalination plant were compared in a winter environment. 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 / yuan 13383 13383 High-pressure pump start-stop cost / yuan 0 0 Water pump operation and maintenance cost / yuan 8579 10724 Water pump start-stop cost / yuan 0 0 Turbine operation and maintenance cost / yuan 0 2230 Turbine start-up and shutdown cost / yuan 0 0 Interaction cost / yuan 4840 3522 Electric energy storage operation and maintenance cost / yuan 128 23 Wind turbine operation and maintenance cost / yuan 369 369 Wind abandonment penalty / yuan 0 0 Emission penalty / yuan 4099 0 Desalination plant energy consumption / kWh 20157 21784 Turbine power generation / kWh 0 3340

[0340] As can be seen from Table 5, the total cost of the reverse osmosis-pressure delayed osmosis desalination plant is lower than that of the reverse osmosis desalination plant. This is because pressure delayed osmosis can recover the energy in the brine to reduce the interaction cost, and the treatment of the brine reduces the discharge penalty. The turbine power generation accounts for 15.33% of the energy consumption of the desalination plant, and the energy saving effect is more obvious.

[0341] contrast Figure 6 and Figure 7 The common point is that in both cases, the desalination plants purchase a large amount of electricity when the electricity purchase price is low, that is, during the 1-7 period, to increase fresh water production; and stop purchasing electricity when the electricity purchase price is high during the 10-12 and 17-21 periods, and rely entirely on wind power to produce water, thereby reducing costs. In both cases, electric energy storage is used to shift the peak power consumption to reduce the cost of purchasing electricity. Figure 7 At each time period, the turbine collects energy through pressure-delayed permeation to reduce energy consumption.

[0342] In summary, the present invention discloses a reverse osmosis desalination plant scheduling method taking into account the pressure delayed osmosis link. The present invention fully exploits the flexibility of the desalination plant, can make the load stable and perform peak load shifting, and improves the economy and environmental protection of the desalination plant through pressure delayed osmosis.

Claims

1. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link, characterized in that: The following steps are involved: 1) Obtain the basic parameters of the desalination plant. 2) Based on the basic parameters, the desalination process is modeled to obtain the desalination plant equipment unit model; 3) Based on the basic model of the desalination plant equipment unit model, establish the operating constraints of the desalination plant; 4) Combine the desalination plant equipment unit model and the desalination plant operation constraints to build the overall scheduling model of the desalination plant; 5) Solve the overall scheduling model of the seawater desalination plant and obtain the optimal scheduling plan of the seawater desalination plant.

2. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 1, characterized in that: The basic parameters of a desalination plant include parameters of each device in the desalination plant, time-of-use electricity purchase / sale price, fresh water load, predicted wind power, seawater concentration, and seawater temperature.

3. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 1, characterized in that: The 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.

4. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 3, characterized in that: The water intake pump model is shown below: Wherein, the subscript t represents the time period t; P t In and are the water pump power and water flow in the tth period respectively; H In is the head of the water pump; ρ and g are the density of water and the acceleration of gravity respectively; η In The efficiency of water pump operation; The reverse osmosis high pressure pump unit model is shown below: p FD,t =κC FD,t ,p BR,t =κC BR,t ,p PR,t =κC PR,t (7) Among them, P t RO is the high pressure pump power of the reverse osmosis module; Feed seawater flow rate for reverse osmosis module; The pressure applied by the high-pressure pump to the feed seawater; η RO is the operating efficiency of the high-pressure pump of the reverse osmosis module; q PR,t K is the product permeate flow rate; RO , S RO are the permeability coefficient and membrane area of ​​the permeable membrane respectively; is the feed water temperature coefficient; T is the water temperature; N is the number of reverse osmosis membranes; is the hydraulic pressure difference of the reverse osmosis module; p BR,t and p PR,t are the water pressures of concentrated brine and product water respectively; Δπ t is the osmotic pressure difference of the reverse osmosis module; π FD,t , π BR,t and π PR,t are the osmotic pressures of feed seawater, brine and product water, respectively; is the concentration polarization coefficient; C FD,t , C BR,t and C PR,t are the concentrations of feed seawater, concentrated brine and product water respectively; κ is the proportional coefficient between solution osmotic pressure and solution concentration. BR,t is the brine flow rate; R is the reverse osmosis recovery rate; The pressure-delayed osmosis unit model includes a water flow calculation equation, a pressure-delayed osmosis power generation calculation equation, a pressure-delayed osmosis module hydraulic pressure difference calculation equation, and a pressure-delayed osmosis module high-pressure pump power consumption calculation equation; The water flow calculation equation in the pressure delayed permeation module is as follows: Among them, q w,t is the water flow rate through the semipermeable membrane; is the temperature coefficient of concentrated brine in the concentrated brine pool; is the hydraulic pressure difference of the pressure-delayed osmosis module; A, k, S, D, and β are the membrane permeability coefficient, mass transfer coefficient, membrane structure parameter, volume diffusion coefficient, and solute permeability, respectively; The calculation equation of pressure-delayed osmosis power generation is as follows: Among them, P t TUR is the turbine power generation; η TUR is the turbine operating efficiency; The calculation equation of the hydraulic pressure difference of the pressure delayed permeation module is as follows: in, p FS,t and p w,t They are the hydraulic pressure of the pressurized high-salinity extraction solution, the hydraulic pressure of the low-salinity feed solution, and the hydraulic pressure of water passing through the semipermeable membrane; The power consumption calculation equation of the high-pressure pump of the pressure delayed permeation module is as follows: Among them, P t PRO The power consumption of the high pressure pump of the reverse osmosis module; is the concentrated brine flow rate entering the pressure delayed osmosis module; η PRO The operating efficiency of the high-pressure pump of the reverse osmosis module; The energy storage device includes a water reservoir model and an electrical energy storage device model; The reservoir model is as follows: in, and are the water levels of the clean water pool, product water pool and concentrated brine pool during period t respectively; and are the water levels of the clean water tank and the product water tank at time t-1; r Pre is the ratio of the flow rate of pretreated seawater to feed water; The water outflow rate of the product pool; A is the feed seawater flow rate of the pressure delayed osmosis module; CLT , A PRT and A BRT are the bottom areas of the clean water pool, product water pool and concentrated brine pool respectively; T T is the total number of time slots in a scheduling cycle; and They are the initial and final values ​​of the water level in the clear water tank during the scheduling period; and They are the initial and final values ​​of the product pool water level in the scheduling cycle respectively; and They are the initial and final values ​​of the water level in the concentrated brine pool during the scheduling period; h CLT They are the upper and lower limits of the water level in the clear water tank respectively; h PRT They are the upper and lower limits of the product pool water level respectively; h BRT are the upper and lower limits of the brine pool water level respectively; q t is the total freshwater production of all reverse osmosis units during period t; Δt is the scheduling time interval; The solution concentration balance and temperature balance in the reservoir are shown below: Among them, C BRT,t , C BRT,t-1 are the concentrations of the concentrated brine in the concentrated brine pool at time periods t and t-1 respectively; is the water intake flow in the tth period; C In,t is the water concentration; T In,t 、T BR,t The water intake temperature of the water intake pump and the concentrated brine temperature; The concentration balance of the pressure-delayed osmosis module in the reservoir is shown below: in, is the concentration of discharged water; The electric energy storage model is as follows: Among them, P t CH and P t DCH are the charging and discharging power of the energy storage respectively; η CH and η DCH are the charging and discharging efficiency of electric energy storage respectively; is the energy storage capacity at time t-1 during period t; and are 0-1 variables representing the charging and discharging states of the energy storage; and They are the initial and final values ​​of the electric energy storage capacity in the dispatching cycle respectively; P CH , are the lower and upper limits of the electric energy storage charging power respectively; P DCH , are the lower and upper limits of the energy storage discharge power respectively; Δt is the scheduling time interval; E BE , They are the lower and upper limits of the electric energy storage capacity respectively.

5. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 1, characterized in that: The operating constraints of the seawater desalination plant include water intake pump flow constraint, water intake pump power constraint, water intake pump start and stop constraint, reverse osmosis module high-pressure pump energy consumption linear constraint, reverse osmosis module and pressure delayed osmosis module high-pressure pump flow constraint, high-pressure pump power constraint, high-pressure pump working pressure constraint, high-pressure pump start and stop times constraint, reverse osmosis unit total water production constraint, turbine power constraint, turbine start and stop constraint, wind turbine operation constraint, and power balance constraint.

6. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 5, characterized in that: The water intake pump flow constraints are as follows: in, is the water intake pump flow; is a 0-1 variable representing the working status of the water intake pump; and q In They are the upper and lower limits of the water intake pump flow rate respectively; The water intake pump power constraints are as follows: Among them, P In,UP and P In,DN They are the upper and lower climbing power limits of the water intake pump respectively; is the power of the water intake pump in period t and period t-1; P t In The upper and lower limits of the water pump power; is a 0-1 variable representing the operating status of the water intake pump during period t and period t-1; The start and stop constraints of the water intake pump are as follows: Among them, C In 、F t In are the single start-stop cost of the water pump and the total start-stop cost in time period t; M In The maximum allowed start and stop times of the water intake pump within the scheduling cycle; is a 0-1 variable representing the operating status of the water intake pump during period t+1; The high pressure pump flow constraints for the reverse osmosis module and the pressure delayed osmosis module are as follows: in, Feed seawater flow rate to the reverse osmosis module; A 0-1 variable representing the working state of the high-pressure pump of the reverse osmosis module; and They are the upper and lower limits of the flow rate of the high-pressure pump of the reverse osmosis module respectively; Feed seawater flow rate for the pressure delayed osmosis module; is a 0-1 variable that characterizes the working state of the high-pressure pump of the pressure-delayed permeation module; and They are the upper and lower limits of the high-pressure pump flow rate of the pressure delayed osmosis module respectively. The linear constraint on the energy consumption of the high-pressure pump of the reverse osmosis module is as follows: in, P is the upper and lower limits of the reverse osmosis module working pressure; t RO is the high pressure pump power of the reverse osmosis module; The pressure applied by the high-pressure pump to the feed seawater; η RO The operating efficiency of the high-pressure pump of the reverse osmosis module; Output power for the high pressure pump of the reverse osmosis module; The power constraints of the high-pressure pumps in the reverse osmosis module and the pressure delayed osmosis module are as follows: Among them, P RO,UP and P RO,DN are the upper and lower climbing power limits of the high-pressure pump of the reverse osmosis module respectively; P t RO , is the power of the high-pressure pump of the reverse osmosis module in time period t and time period t-1; The upper and lower limits of the high-pressure pump power of the reverse osmosis module; is a 0-1 variable representing the operating status of the high-pressure pump of the reverse osmosis module during period t and period t-1; PRO,UP and P PRO,DN are the upper and lower climbing power limits of the high-pressure pump of the pressure delayed permeation module respectively; P t PRO , is the power of the high-pressure pump of the pressure delayed permeation module in time periods t and t-1; The upper and lower limits of the high-pressure pump power of the pressure delayed permeation module; is a 0-1 variable representing the operating state of the high-pressure pump of the pressure-delayed permeation module during period t and period t-1; The operating pressure constraints of the high-pressure pumps of the reverse osmosis module and the pressure delayed osmosis module are as follows: in, is the working pressure of the reverse osmosis unit in period t and period t-1; is the upper and lower limits of the reverse osmosis module working pressure; p RO,UP and p RO,DN The upper limit of the increment and decrement of the working pressure of the reverse osmosis module per unit time period; Δ p RO The upper and lower limits of the pressure difference of the reverse osmosis module; is the working pressure of the pressure delayed permeation unit at time period t and time period t-1; is the upper and lower limits of the working pressure of the pressure delayed permeation module; p PRO,UP and p PRO,DN Δπ is the upper limit of the increment and decrement of the working pressure of the pressure delayed penetration module per unit time period; t is the osmotic pressure difference of the reverse osmosis module; is the pressure difference of the reverse osmosis module; The high-pressure pump start and stop times constraints are as follows: Among them, M RO M is the maximum allowed start and stop times of the high-pressure pump of the reverse osmosis module within the scheduling period; PRO The maximum allowed start and stop times of the high-pressure pump of the pressure-delayed permeation module within the scheduling period; The total water production constraint of the reverse osmosis unit is as follows: Among them, S RO is the lower limit of freshwater production within the scheduling period; Δt is the scheduling time interval; q PR,t The water flow rate for product penetration; The turbine flow constraints are as follows: Among them, q w,t is the turbine flow; is a 0-1 variable representing the working state of the turbine; and q In are the upper and lower limits of turbine flow respectively; q w , are the lower and upper limits of turbine flow; The turbine power constraints are as follows: Among them, P TUR,UP and P TUR,DN are the upper and lower climbing power limits of the turbine respectively; P t TUR , is the power of the turbine in period t and period t-1; P t TUR are the upper and lower limits of turbine power; It is a 0-1 variable that characterizes the operating status of the turbine in period t and period t-1. The turbine start and stop constraints are as follows: Among them, M TUR The maximum allowable start and stop times of the turbine within the dispatching period. The operating constraints of wind turbines are as follows: 0≤P t WAG ≤P t WG (35) Among them, P t WG and P t WAG They are the predicted power and curtailed power of wind turbines in desalination plants; The power balance constraints are as follows: Among them, P t P2D The amount of electricity purchased by the desalination plant from the distribution network; P t D2P The amount of electricity sold to the distribution grid for the desalination plant; is the interactive power limit between the desalination plant and the distribution network; P t RO is the high pressure pump power of the reverse osmosis module; P t In is the water pump power in the tth period; P t CH and P t DCH are the charging and discharging power of the energy storage respectively; P t PRO P is the power consumption of the high pressure pump of the reverse osmosis module; t TUR is the power generated by the turbine.

7. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 1, characterized in that: The objective function of the overall scheduling model of the desalination plant is as follows: minC=C OP +C SU +C EN +C BE +C WG +C AW +C ENV (37) Among them, T T is the number of scheduling period periods; C is the total operating cost of the desalination plant, Equipment operation and maintenance costs, is the equipment start-up and shutdown cost, To reduce the power interaction cost between the desalination plant and the distribution network, For the operation and maintenance cost of energy storage, is the wind turbine operation and maintenance cost, Punishment for abandoning the wind, Punishment for discharging brine.

8. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 7, characterized in that: Equipment operation and maintenance costs Equipment start-up and shutdown costs Power interaction cost between desalination plant and distribution network Energy storage operation and maintenance costs Wind turbine operation and maintenance costs Wind abandonment penalty Brine discharge penalty As shown below: in and They are the operation and maintenance cost coefficient of the high-pressure pump of the reverse osmosis module, the operation and maintenance cost coefficient of the high-pressure pump of the pressure delayed osmosis module and the operation and maintenance cost coefficient of the turbine; and They are the single start-stop cost of the high-pressure pump of the reverse osmosis module, the single start-stop cost of the high-pressure pump of the pressure delayed osmosis module and the single start-stop cost of the turbine; The unit prices of electricity purchased / sold by the desalination plant to the distribution network are respectively; is the operation and maintenance cost coefficient of electric energy storage; is the wind turbine operation and maintenance cost coefficient; is the wind abandonment penalty coefficient; is the environmental pollution penalty coefficient; C ST is the standard concentration for seawater discharge; is the concentration of discharged water.

9. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 6, characterized in that: The constraints of the overall scheduling model of the desalination plant are the desalination plant operation constraints (20)-(36).

10. A method for scheduling a reverse osmosis desalination plant taking into account the pressure delayed osmosis link according to claim 1, characterized in that: Tools for solving the overall dispatch model of a desalination plant include the Gurobi solver.

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