Low-head high-amplitude pumped storage power station multi-task comprehensive utilization system and method

Abstract

The application provides a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system and method, which comprises an upper reservoir, a lower reservoir, a diversion tunnel, a pumped storage unit, a connecting pipeline and a peripheral water distribution main; the upper reservoir and the lower reservoir simultaneously have water supply functions and functions of guaranteeing operation and power generation of the pumped storage unit; water head differences are obtained through real-time monitoring of water level changes of the upper reservoir and the lower reservoir by an intelligent monitoring system; water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head differences, water supply requirements of regions around the project are preferentially met, and safe and stable operation of the power grid is simultaneously guaranteed as much as possible. The application optimizes power generation, water supply, ecological benefit targets by using a multi-objective genetic algorithm; simultaneously, excavated earthwork processing is used as building aggregate, the water surface of the power station is used to improve ecology, and local economy is driven. The method realizes multi-task cooperation of water supply, power generation, aggregate supply, ecological improvement and economic development, improves comprehensive benefits of the project, and promotes sustainable development.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical fields of water conservancy and electric power, and particularly relates to a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system and method. BACKGROUND

[0002] At present, there are many reservoirs with water supply as the main task, and a large amount of research has been conducted on the water supply task of the reservoir. For example, Beijing Miyun Reservoir mainly functions to supply water, and also serves the purposes of flood control, irrigation, power generation, breeding and tourism. For another example, Fushun's Dahuangshan Reservoir is a large-scale water conservancy project mainly serving the purpose of water supply, and also serving the purposes of flood control, irrigation, power generation and fish breeding. The construction of the above-mentioned reservoirs is mainly to provide water supply sources for surrounding cities, and during the engineering planning, construction and operation, engineering research and construction are carried out only for the utilization of water resources.

[0003] Pumped storage technology has been successfully used for more than 100 years, and is the most mature, reliable and economical technology in the current large-scale electric energy storage. Pumped storage refers to the storage of water in a high reservoir, and when needed, the water is released to generate electricity by using hydraulic turbine. At present, there are many studies on pumped storage, and there is a large amount of engineering experience. However, in the previous studies, the main task of pumped storage power station is power generation, and the function is too single, and the comprehensive benefits of the project are not fully utilized.

[0004] At present, there are many studies on the supply of building aggregates, but there are few precedents for studies that consider the demand for aggregates of the project itself, while minimizing resource waste, and taking into account the supply of aggregates in the surrounding areas, local interests and other factors.

[0005] In summary, in the previous studies on reservoir water supply, pumped storage power station power generation, building aggregate supply and ecological restoration, only single function or single field is considered, and there are few precedents for studies that can maximize the benefits of a single project in multiple fields. Therefore, there is an urgent need for a multi-task comprehensive utilization method for water supply reservoirs to maximize the benefits of the project. SUMMARY

[0006] In view of the defects in the prior art, the present application provides a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system and method, which can effectively solve the above problems.

[0007] The technical scheme adopted by the present application is as follows:

[0008] The present application provides a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system, which comprises an upper reservoir, a lower reservoir, a water diversion tunnel, a pumped storage unit, a connecting pipeline and a surrounding water distribution main line.

[0009] The upper reservoir provides online storage and water supply for the surrounding water distribution project, and the excavated materials during construction are used for building aggregate supply in the surrounding area.

[0010] The lower reservoir provides online storage and water supply for the surrounding water distribution project, and the excavated materials during construction are used for building aggregate supply in the surrounding area.

[0011] The water diversion tunnel is connected between the upper reservoir and the lower reservoir, and is used for mutual supplement of water between the upper reservoir and the lower reservoir.

[0012] The pumping and storage unit is arranged between the upper reservoir and the lower reservoir, and the reversible pump-turbine unit of the pumping and storage unit is used for water supplement, energy dissipation and power generation through the water diversion tunnel; specifically, the energy of water flow between the upper reservoir and the lower reservoir is converted into mechanical energy for driving various mechanical equipment or generating electricity.

[0013] The connecting pipeline is connected with the lower reservoir and the surrounding water distribution main line respectively, and is used for mutual supplement of water between the lower reservoir and the surrounding water distribution main line.

[0014] The application also provides a low-head high-amplitude pumped storage power station multi-task comprehensive utilization method based on a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system.

[0015] Step S1, building aggregate supply: processing the excavated earthwork of the upper reservoir and the lower reservoir as building aggregate to supply to the surrounding project;

[0016] Step S2, the upper reservoir and the lower reservoir have water supply function and function of guaranteeing operation and power generation of the pumping and storage unit; specifically, the intelligent monitoring system is used to monitor the water level change of the upper reservoir and the lower reservoir in real time to obtain the water head difference ΔH; the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head difference ΔH, the water supply requirement of the surrounding area of the project is preferentially met, and the safe and stable operation of the power grid is guaranteed as much as possible.

[0017] Preferably, step S2 is specifically as follows:

[0018] Step S2.1, according to the water head amplitude range allowed by the pumping and storage unit, the water level change is divided into three gears: normal operation gear, early warning gear and emergency control gear;

[0019] Step S2.2, the gear to which the current water level change belongs is determined according to the water head difference ΔH;

[0020] Under the normal operation gear, the water head difference ΔH satisfies:

[0021] △H min,limit +△H safe≤△H≤△H max,limit -△H safe

[0022] wherein:△H safe is a set safety water head margin for ensuring the pumped storage unit to run in a stable and efficient interval;△H min,limit and△H max,limit are the minimum and maximum water heads allowed when the pumped storage unit is running, respectively;

[0023] Under the pre-warning gear, the water head difference△H satisfies:

[0024] △H min,limit ≤△H<△H min,limit +△H safe

[0025] or△H max,limit -△H safe <△H≤△H max,limit

[0026] Under the emergency control gear, the water head difference△H satisfies:

[0027] △H<△H min,limit or△H>△H max,limit

[0028] Step S2.3, according to the gear where the current water level change is located, the corresponding reservoir water quantity scheduling strategy is executed:

[0029] If it is the normal operation gear, the current running state is maintained, and the water levels of the upper and lower reservoirs are adjusted according to the conventional scheduling strategy, and the water supply and power generation demands are preferentially met;

[0030] If it is the pre-warning gear, the changes of the water levels of the upper and lower reservoirs are closely observed, the reservoir water quantity scheduling strategy is adjusted, the safe and stable operation of the pumped storage unit is preferentially ensured, and the water supply demand is as much as possible met;

[0031] If it is the emergency control gear, emergency measures need to be taken immediately, the water quantity exchange between the upper and lower reservoirs is quickly adjusted, the safety of the pumped storage unit is preferentially ensured, part of the non-key water supply tasks are suspended, and the damage of the pumped storage unit or system failure is avoided.

[0032] Preferably, the set safety water head margin△H safe is determined by using the following adaptive safety boundary formula based on the unit performance curve:

[0033] △H safe =f(η(t),P(t),Q(t),T(t))

[0034] Wherein: f() is the adaptive security boundary function based on the unit performance curve; η(t) is the real-time efficiency coefficient of pumped storage unit, P(t) is the output power of pumped storage unit, Q(t) is the flow through the pumped storage unit, T(t) is the water temperature environment parameter.

[0035] Preferably, the upper and lower reservoir water level operating range needs to meet the maximum water head amplitude allowed by the pumped storage unit:

[0036] △H min,limit = H up,min -H down,max

[0037] △H max,limit = H up,max -H down,min

[0038] △H limit =△H max,limit -△H min,limit ≥△H

[0039] Wherein: H down,min and H down,max are the minimum and maximum water levels of the lower reservoir under the condition of meeting water supply and the water head amplitude limit of the pumped storage unit; H up,min and H up,max are the minimum and maximum water levels of the upper reservoir under the condition of meeting water supply and the water head amplitude limit of the pumped storage unit;△H min,limit and△H max,limit are the minimum and maximum water heads allowed by the pumped storage unit during operation;△H limit is the maximum water head allowed by the pumped storage unit.

[0040] Preferably, when the lower reservoir needs to supply water to the surrounding water trunk, the water level of the lower reservoir changes as follows:

[0041]

[0042] Wherein: Q supply is the water supply flow, A down is the average water surface area of the lower reservoir, is the water level of the lower reservoir before the change, is the water level of the lower reservoir after the change,△t is the water supply time;

[0043] At this time, the minimum operating water level of the lower reservoir decreases due to the supply of water to the surrounding water trunk, resulting in a water head amplitude exceeding the maximum water head amplitude allowed by the pumped storage unit, i.e.△H limit <△H, the maximum operating water level of the upper reservoir needs to be reduced, and water needs to be discharged from the upper reservoir to the lower reservoir in time for compensation, using the real-time compensation flow calculation formula:

[0044]

[0045] wherein: Q comp is the compensation flow, A up is the average water surface area of the upper reservoir, is the water level of the upper reservoir before compensation;

[0046] When the upper reservoir continuously supplies water to the lower reservoir to replenish the water, the minimum operating water level of the upper reservoir decreases, resulting in a water head amplitude exceeding the maximum water head allowed by the pumping and storage unit, i.e.△H limit <△H, the maximum operating water level of the lower reservoir needs to be reduced;

[0047] Therefore, by detecting the water level changes of the upper reservoir and the lower reservoir, and dynamically regulating the water level according to the maximum and minimum water head amplitude, the water is smoothly discharged to meet the water demand of the water users.

[0048] Preferably, when dynamically scheduling the water of the upper reservoir and the lower reservoir according to the water head difference△H, a multi-objective optimization algorithm based on genetic algorithm is adopted, taking water supply, power generation, and ecological benefits as objective functions, taking water level, water head, flow, and water balance as constraint conditions, and outputting a Pareto optimal solution set that meets the water supply, power generation, and ecological benefits target through iterative calculation.

[0049] Preferably, the multi-objective optimization algorithm based on genetic algorithm outputs a Pareto optimal solution set that meets the water supply, power generation, and ecological benefits target, specifically:

[0050] Step A1, define a set of decision variables, denoted as:

[0051] [△H up ,△H down , Q gen , Q pump , Q supply ]; wherein,△H up and△H down are the water level changes of the upper reservoir and the lower reservoir, Q gen is the power generation flow, Q pump is the pumping flow, and Q supply is the water supply flow;

[0052] Step A2, define the objective functions and constraint conditions as follows:

[0053] The water supply benefit target B water is related to the water supply flow and water supply reliability, and is expressed as:

[0054] B water =k1×Q supply ×R supply

[0055] wherein: k1 is the water supply benefit coefficient, rsupply is the water supply reliability, with a value range of [0, 1];

[0056] Power generation benefit target B power : related to power generation power and power generation duration:

[0057] B power = k2 x P gen x t gen

[0058] P gen = η x p x g x Q gen x ΔH

[0059] wherein: k2 is a power generation benefit coefficient, t gen is the power generation duration, P gen is the power generation power; η is the total efficiency of the pumped storage unit, p is the density of water, g is the acceleration of gravity;

[0060] Ecological benefit target B eco : related to the satisfaction degree of ecological flow, expressed as:

[0061]

[0062] wherein: k3 is an ecological benefit coefficient, Q eco is the ecological flow demand, Q actual is the actual provided ecological flow;

[0063] Considering the water level, water head, flow and water balance requirements in the actual operation process, the constraint conditions are determined as follows:

[0064] Water level constraint:

[0065] H up,min ≤ H up ≤ H up,max , H down,min ≤ H down ≤ H down,max

[0066] wherein: H up and H down are the water levels of the upper reservoir and the lower reservoir respectively;

[0067] Water head constraint:

[0068] ΔH min,limit ≤ ΔH ≤ ΔH max,limit

[0069] Flow constraint:

[0070] 0 ≤ Q gen ≤ Q gen,max

[0071] 0≤Q pump ≤Q pump,max

[0072] Q supply,min ≤Q supply ≤Q supply,max

[0073] Q eco,min ≤Q eco ≤Q eco,max

[0074] wherein: Q gen,max is the upper limit of power generation flow; Q pump,max is the upper limit of pumping flow; Q supply,min and Q supply,max are the lower limit and upper limit of water supply flow, respectively; Q eco,min and Q eco,max are the lower limit and upper limit of ecological flow demand, respectively;

[0075] Water balance constraint: according to the water balance equation of the reservoir △V=Q in ·△t-Q out ·△t, the water volume change of the upper and lower reservoirs is ensured to be consistent with the actual situation; wherein, △V is the water volume of the reservoir; Q in and Q out are the inflow and outflow of the reservoir, respectively;

[0076] According to the water supply, power generation and ecological benefits, the water supply-power generation-ecological benefit balance index EBI is proposed:

[0077] EBI=(B water / B water-max )^β×(B power / B power-max )^γ×(B eco / B eco-max )^(1-β-γ)

[0078] wherein: B water-max , B power-max , B eco-max are the maximum water supply benefit, the maximum power generation benefit and the maximum ecological benefit, respectively; β and γ are the water supply benefit weight and the power generation benefit weight, respectively;

[0079] Step A3, the genetic algorithm is used to solve the objective function to obtain the optimal solution set of the decision variables.

[0080] Preferably, when the water volume of the upper and lower reservoirs is dynamically scheduled according to the head difference ΔH, the following scheduling operation principles are adopted:

[0081] Comprehensive scheduling operation principles:

[0082] According to the principle of water regulation priority, the water supply requirements of the surrounding areas of the project are met, and the safe and stable operation of the power grid is ensured as much as possible;

[0083] According to the inflow and water regime prediction, the storage and supply water time and quantity are determined in advance, and the storage and supply water plan is formulated;

[0084] According to the inflow of the upper and lower reservoirs and the water demand of the water receiving area, the water supply emergency plan is formulated to deal with the sudden water supply safety accidents caused by serious water pollution or other major safety accidents;

[0085] Water supply dispatching principles:

[0086] When the water receiving area needs the upper and lower reservoirs to store water for supply, water is discharged from the upper reservoir to the lower reservoir through the diversion tunnel, and the water in the lower reservoir is supplied to the surrounding water distribution main through the connecting pipeline;

[0087] For water replenishment dispatching operation, when the upper and lower reservoirs need to be replenished, water is transported from the surrounding water distribution main to the lower reservoir through the connecting pipeline, and then pumped from the lower reservoir to the upper reservoir through the diversion tunnel;

[0088] Power generation dispatching principles:

[0089] After the construction of the pumped storage power station, it undertakes the tasks of system peak shaving, valley filling, frequency regulation, phase regulation and emergency backup in the power grid;

[0090] For peak shaving operation, the pumped storage power station generates power during the peak of the power grid system, solving the problem of power system peak shaving;

[0091] For valley filling operation, the pumped storage power station pumps water when the power system load is low;

[0092] For frequency regulation operation, due to the flexible operation of the pumped storage power station and the fast speed of load increase and decrease, after being put into operation, it tracks the load operation according to the change of system frequency, ensures that the system frequency is within the allowed range, and improves the power supply quality of the entire power system;

[0093] For phase regulation operation, the pumped storage power station not only can output active power, but also has phase regulation function. No matter in which working condition, it can adjust the reactive power output of the system by changing the excitation current; it can not only make up for the lack of reactive power of the system, but also eliminate the excess of reactive power of the system. Especially when the system has excess reactive power, the pumped storage power station can operate in phase regulation mode to absorb the reactive power in the system, thereby reducing the system voltage and ensuring that the system voltage is within the normal range;

[0094] For accident backup, the pumped storage power station carries out normal power generation or pumping operation in the normal operation water level range of upper and lower reservoirs, and when power system accident occurs, the unit without full load can be used to generate accident power to replace the unit stopped due to failure in the system; in the pumping condition, the whole unit can be withdrawn from the pump operation according to the system requirement to reduce the load of the power grid, play the role of accident backup, and can be converted to power generation operation in a short time and bear the accident backup; in the static condition, the power generation can be started urgently.

[0095] The low-head high-amplitude pumped storage power station multi-task comprehensive utilization system and method provided by the application has the following advantages:

[0096] The low-head high-amplitude pumped storage power station multi-task comprehensive utilization system and method provided by the application collects data by means of an intelligent monitoring system, and dynamically schedules water quantity according to water level changes. A multi-objective genetic algorithm is used to optimize the power generation, water supply, and ecological benefit targets; at the same time, excavated earthwork processing is used as building aggregate, and the water surface of the power station is used to improve the ecology and drive local economy. The method solves the disadvantages of single function utilization of traditional projects, realizes the multi-task cooperation of water supply, power generation, aggregate supply, ecological improvement, and economic development, improves the comprehensive benefits of the project, and promotes sustainable development. BRIEF DESCRIPTION OF DRAWINGS

[0097] Figure 1 The low-head high-amplitude pumped storage power station structure provided by the application takes into account water supply, power generation, and ecological benefits;

[0098] Figure 2 The water level dynamic regulation flow chart provided by the application;

[0099] Figure 3 The multi-objective optimization algorithm flow chart provided by the application.

[0100] 1: upper reservoir; 2: lower reservoir; 3: water diversion tunnel; 4: pumped storage unit; 5: connecting pipeline. DETAILED DESCRIPTION

[0101] In order to make the technical problems, technical solutions and beneficial effects solved by the application clearer and more apparent, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and do not limit the application.

[0102] The application aims to provide a low-head high-amplitude pumped storage power station multi-task comprehensive utilization method which takes into account water supply, power generation and ecological benefits, which collects data by means of an intelligent monitoring system, and dynamically schedules water volume according to water level changes. A multi-objective genetic algorithm is used to optimize the power generation, water supply, and ecological benefit targets. At the same time, excavated earthwork is processed as building aggregate, and the power station water surface is used to improve the ecology and drive local economy. The method solves the drawbacks of traditional single-function utilization of projects, realizes the multi-task cooperation of water supply, power generation, aggregate supply, ecological improvement and economic development, improves the comprehensive benefits of projects, and promotes sustainable development.

[0103] Reference Figure 1 The application provides a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system, which comprises an upper reservoir, a lower reservoir, a water diversion tunnel, a pumped storage unit, a connecting pipeline and a surrounding water distribution main;

[0104] The upper reservoir provides online storage and water supply for the surrounding water distribution project, and the excavated material during construction is used for building aggregate supply in the surrounding area.

[0105] The lower reservoir provides online storage and water supply for the surrounding water distribution project, and the excavated material during construction is used for building aggregate supply in the surrounding area.

[0106] The water diversion tunnel is connected between the upper reservoir and the lower reservoir, and is used for mutual supply of water volume between the upper reservoir and the lower reservoir.

[0107] The pumped storage unit is arranged between the upper reservoir and the lower reservoir, and the reversible pump-turbine unit of the pumped storage unit is used for water supplementing, energy dissipation and power generation through the water diversion tunnel. Specifically, it is used for converting the energy of water flow between the upper reservoir and the lower reservoir into mechanical energy, which is used to drive various mechanical equipment or generate electricity.

[0108] The connecting pipeline is connected with the lower reservoir and the surrounding water distribution main respectively, and is used for mutual supply of water volume between the lower reservoir and the surrounding water distribution main.

[0109] The application further provides a low-head high-amplitude pumped storage power station multi-task comprehensive utilization method, comprising the following steps:

[0110] Step S1, building aggregate supply: processing the excavated earthwork of the upper reservoir and the lower reservoir as building aggregate to supply to surrounding projects;

[0111] In step S2, the upper reservoir and the lower reservoir have the water supply function and the function of ensuring the operation of the pumped storage unit to generate power at the same time; specifically, the water level change of the upper reservoir and the lower reservoir is monitored in real time through an intelligent monitoring system to obtain the water head difference AH; the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head difference AH, the water supply requirement of the surrounding area of the project is preferentially met, and the safe and stable operation of the power grid is ensured as much as possible.

[0112] Step S2 specifically includes:

[0113] In step S2.1, according to the water head amplitude range allowed by the pumped storage unit, the water level change is divided into three gears: a normal operation gear, a pre-warning gear and an emergency control gear.

[0114] In step S2.2, the gear to which the current water level change belongs is determined according to the water head difference AH.

[0115] Under the normal operation gear, the water head difference AH satisfies:

[0116] △H min,limit +△H safe ≤△H≤△H max,limit -△H safe

[0117] Wherein: AH is the set safety water head allowance, which is used to ensure that the pumped storage unit operates in a stable and efficient interval; AH and AH are the minimum water head and the maximum water head allowed when the pumped storage unit operates, respectively. safe min,limit max,limit

[0118] The set safety water head allowance AH is determined by using the following adaptive safety boundary formula based on the unit performance curve: safe

[0119] AH = f (η (t), P (t), Q (t), T (t) ) safe

[0120] Wherein: f () is an adaptive safety boundary function based on the unit performance curve; η (t) is the real-time efficiency coefficient of the pumped storage unit, P (t) is the output power of the pumped storage unit, Q (t) is the flow through the pumped storage unit, and T (t) is the water temperature environment parameter.

[0121] Under the pre-warning gear, the water head difference AH satisfies:

[0122] △H min,limit ≤△H<△H min,limit +△H safe

[0123] or AH - AH nax,linit -△H safe <△H≤△H max,limit ​​​​​

[0124] In the emergency control gear, the water head difference AH satisfies:

[0125] AH < AH min,limit or AH > AH max,limit

[0126] Step S2.3, according to the gear of the current water level change, the corresponding reservoir water quantity scheduling strategy is executed:

[0127] If it is a normal operation gear, the current operation state is maintained, and the water levels of the upper and lower reservoirs are adjusted according to the conventional scheduling strategy, and the water supply and power generation demand are preferentially met;

[0128] If it is a pre-warning gear, the upper and lower reservoir water level changes are closely observed, the reservoir water quantity scheduling strategy is adjusted, the safe and stable operation of the pumping storage unit is preferentially guaranteed, and the water supply demand is as much as possible met;

[0129] If it is an emergency control gear, emergency measures need to be taken immediately, the water quantity exchange between the upper and lower reservoirs is quickly adjusted, the safety of the pumping storage unit is preferentially guaranteed, part of the non-key water supply task is suspended, and the damage of the pumping storage unit or system failure is avoided.

[0130] In the operation process of the upper and lower reservoirs, the water level operation range of the upper and lower reservoirs needs to meet the maximum water head amplitude allowed by the pumping storage unit:

[0131] AH min,limit = H up,min - H down,max

[0132] AH max,limit = H up,max - H down,min

[0133] AH limit = AH max,limit - AH min,limit ≥ AH

[0134] Wherein: H down,min and H down,max are the minimum and maximum water levels of the lower reservoir under the condition of meeting the water supply and the water head amplitude limit of the pumping storage unit; H up,min and H up,max are the minimum and maximum water levels of the upper reservoir under the condition of meeting the water supply and the water head amplitude limit of the pumping storage unit; AH min,limit and AH max,limit are the minimum and maximum water heads allowed by the pumping storage unit when it is running; AH limit is the maximum water head allowed by the pumping storage unit.

[0135] When the lower reservoir needs to supply water to the surrounding water trunk, the water level of the lower reservoir changes as follows:

[0136]

[0137] Q = Q + Q supply Q = Q + Q down Q = Q + Q Q = Q + Q Q = Q + Q

[0138] At this time, the minimum operating water level of the lower reservoir decreases due to the water supply to the surrounding water supply pipeline, so that the water head amplitude exceeds the maximum water head amplitude allowed by the pumping and storage unit, that is, AH limit AH, the maximum operating water level of the upper reservoir needs to be reduced, and water is discharged from the upper reservoir to the lower reservoir in time to compensate, and a real-time compensation flow calculation formula is adopted:

[0139]

[0140] Q = Q + Q comp Q = Q + Q up Q = Q + Q Q = Q + Q

[0141] When the upper reservoir continuously supplies water to the lower reservoir to supplement the water, the minimum operating water level of the upper reservoir decreases, so that the water head amplitude exceeds the maximum water head allowed by the pumping and storage unit, that is, AH limit AH, the maximum operating water level of the lower reservoir needs to be reduced;

[0142] Therefore, by detecting the water level changes of the upper reservoir and the lower reservoir, the water level is dynamically controlled according to the maximum and minimum water head amplitude, and the water is smoothly discharged to meet the water demand of the water user.

[0143] In the present application, when the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head difference AH, a multi-objective optimization algorithm based on genetic algorithm is adopted, the water supply, power generation and ecological benefit are taken as the objective function, the water level, water head, flow and water quantity balance are taken as the constraint condition, and the Pareto optimal solution set meeting the water supply, power generation and ecological benefit target is output through iterative calculation.

[0144] The multi-objective optimization algorithm based on genetic algorithm outputs the Pareto optimal solution set meeting the water supply, power generation and ecological benefit target, and specifically:

[0145] Step A1, a group of decision variables are defined, which are represented as:

[0146] [△H up , AH down , Q gen , Q pump , Q supply]; wherein, △H up and △H down are the water level change of the upper reservoir and the lower reservoir, respectively, Q gen is the power generation flow, Q oump is the pumping flow, Q supply is the water supply flow;

[0147] Step A2, define the objective function and the constraint condition as follows:

[0148] Water supply benefit objective B water : related to the water supply flow and the water supply reliability, expressed as:

[0149] B water = k1 x Q supply x R supply

[0150] wherein: k1 is the water supply benefit coefficient, R supply is the water supply reliability, with a value range of [0, 1];

[0151] Power generation benefit objective B power : related to the power generation power and the power generation time length:

[0152] B power = k2 x P gen x t gen

[0153] P gen = η x p x g x Q gen x △H

[0154] wherein: k2 is the power generation benefit coefficient, t gen is the power generation time length, P gen is the power generation power; η is the total efficiency of the pumping and storage unit, p is the density of water, and g is the acceleration of gravity;

[0155] Ecological benefit objective B eco : related to the satisfaction degree of the ecological flow, expressed as:

[0156]

[0157] wherein: k3 is the ecological benefit coefficient, Q eco is the ecological flow demand, Q actual is the actual provided ecological flow;

[0158] Considering the water level, water head, flow and water balance requirements in the actual operation process, the constraint condition is determined as follows:

[0159] Water level constraint:

[0160] H up,min ≤ Hup ≤H up,max , H down,min ≤H down ≤H down,max

[0161] where H up and H down are the water levels of the upper reservoir and the lower reservoir, respectively;

[0162] Head constraint:

[0163] △H min,limit ≤△H≤△H max,limit

[0164] Flow constraint:

[0165] 0≤Q gen ≤Q gen,max

[0166] 0≤Q pump ≤Q pump,max

[0167] Q supply,min ≤Q supply ≤Q supply,max

[0168] Q eco,min ≤Q eco ≤Q eco,max

[0169] where Q gen,max is the upper limit of power generation flow; Q pump,max is the upper limit of pumping flow; Q supply,min and Q supply,max are the lower and upper limits of water supply flow, respectively; Q eco,min and Q eco,max are the lower and upper limits of ecological flow demand, respectively;

[0170] Water balance constraint: according to the water balance equation of the reservoir △V = Q in ·△t - Q out ·△t, the water volume change of the upper and lower reservoirs is ensured to be consistent with the actual situation; where △V is the water volume of the reservoir; Q in and Q out are the inflow and outflow of the reservoir, respectively;

[0171] According to the water supply, power generation, and ecological benefits, the water supply-power generation-ecological benefit balance index EBI is proposed:

[0172] EBI = (B water / B water-max )^β × (B power / B power-max )^γ × (Beco / B eco-max )^(1-β-γ)

[0173] Wherein: B water-max , B power-max , B eco-max , respectively, the maximum water supply benefit, the maximum power generation benefit and the maximum ecological benefit; beta and gamma, respectively, the water supply benefit weight and power generation benefit weight;

[0174] Step A3, genetic algorithm is used to solve the objective function, and the optimal solution set of decision variables is obtained.

[0175] In the present application, when the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the head difference Delta H, the following scheduling operation principles are adopted:

[0176] Comprehensive scheduling operation principle:

[0177] According to the principle that the electric regulation is subject to the water regulation, the water supply requirements of the surrounding areas of the project are preferentially met, and the safe and stable operation of the power grid is ensured as much as possible;

[0178] According to the inflow and water regime prediction, the regulation and storage water supply time and quantity are judged in advance, and the regulation and storage water supply plan is formulated;

[0179] According to the inflow of the upper reservoir and the lower reservoir and the water demand of the water receiving area, an emergency plan for water supply is formulated to deal with the sudden water supply safety accidents caused by serious water pollution or other major safety accidents;

[0180] Water supply scheduling principle:

[0181] When the water receiving area needs the upper reservoir and the lower reservoir to carry out interannual or intra-annual regulation and storage water supply, water is discharged from the upper reservoir to the lower reservoir through the diversion tunnel, and the water of the lower reservoir is supplied to the surrounding water distribution main through the connecting pipeline;

[0182] For water replenishment scheduling operation, when the upper reservoir and the lower reservoir need to be replenished, water is transported from the surrounding water distribution main to the lower reservoir through the connecting pipeline, and then pumped from the lower reservoir to the upper reservoir through the diversion tunnel;

[0183] Power generation scheduling principle:

[0184] After the pumped storage power station is built, it undertakes the tasks of system peak regulation, valley filling, frequency regulation, phase regulation and emergency backup in the power grid;

[0185] For peak regulation operation, the pumped storage power station generates power when the power grid system is in power consumption peak, solving the problem of power system peak regulation;

[0186] For valley filling operation, the pumped storage power station pumps water when the power system load is in low valley;

[0187] For frequency modulation operation, due to the flexible operation of pumped storage power station, the load can be increased or decreased quickly, and after being put into operation, the load operation can be tracked according to the change of system frequency to ensure that the system frequency is within the allowed range and improve the power supply quality of the whole power system.

[0188] For phase modulation operation, pumped storage power station not only can output active power, but also has phase modulation function. In any operating condition, the reactive power output of the system can be adjusted by changing the excitation current. It can not only make up for the lack of reactive power of the system, but also eliminate the excess of reactive power of the system. Especially when the system has excess reactive power, pumped storage power station can operate in phase modulation mode to absorb the reactive power in the system, thereby reducing the system voltage and ensuring that the system voltage is within the normal range.

[0189] For emergency standby, when the pumped storage power station operates normally in the normal operating water level range of the upper and lower reservoirs, if an accident occurs in the power system, the unit without full load can be used to output emergency power to replace the unit stopped due to failure in the system in the power generation condition. In the pumping condition, the whole unit can be withdrawn from the pump operation to reduce the load of the power grid to play the role of emergency standby, and can be converted to power generation operation in a short time and bear the emergency standby. In the static condition, the power generation can be started urgently.

[0190] An embodiment will be introduced below:

[0191] The embodiment provides a multi-task comprehensive utilization system of low-head high-amplitude pumped storage power station, which is a low-head high-amplitude pumped storage power station considering water supply, power generation and ecological benefits, and comprises an upper reservoir, a lower reservoir, a water diversion tunnel, pumped storage units, a connecting pipeline and a surrounding water distribution trunk.

[0192] The upper reservoir can store water for city water supply, and the excavated materials in the construction process can be used for building aggregate supply in the surrounding area.

[0193] The lower reservoir can store water for city water supply, and the excavated materials in the construction process can be used for building aggregate supply in the surrounding area.

[0194] The upper reservoir and the lower reservoir have water supply function at the same time, and when they play the role of water supply, they can be called water supply reservoirs, and have the following characteristics: the stored water in the upper and lower reservoirs can be used to provide online storage for the surrounding water distribution trunk and provide strong guarantee for water supply safety, and increase the ability of the city to cope with water resource shortage, uneven coming water in flood and drought seasons, sudden water pollution events, water supply line maintenance, ice period operation and emergency water supply.

[0195] The water diversion tunnel is connected between the upper and lower reservoirs and is used for mutual supply of water between the upper and lower reservoirs.

[0196] The pumped storage unit adopts a bidirectional generator set and is arranged between the upper reservoir and the lower reservoir to generate electricity by using the reversible pump-turbine set. The turbine set is used to convert the energy of water flow between the upper reservoir and the lower reservoir into mechanical energy to drive various mechanical equipment or generate electricity. The reversible pump-turbine set is arranged between the high-level water storage area and the low-level water storage area and is used to supplement water, dissipate energy and generate electricity by the water turbine set through the water diversion tunnel.

[0197] The connecting pipeline is used for mutual supplement of water quantity between the lower reservoir and the water distribution main.

[0198] In the application, the upper and lower reservoirs are excavated to supply construction aggregates: the excavated earth and stone are fully utilized in various aspects of engineering construction, greatly saving construction cost, greatly reducing land resource occupation, and correspondingly reducing the adverse effects of the piled excavated materials on regional land productivity, ecological environment, river water quality, and residents' production and life. In addition to the utilization measures, high-quality green construction aggregates can be centrally supplied to the surrounding cities according to the construction of the surrounding cities.

[0199] In the application, the water storage capacity of the upper and lower reservoirs can provide online storage and water supply for the surrounding water distribution projects, the excavated materials during construction can be used to supply construction aggregates for the surrounding areas, construction cost is saved, land resource occupation is reduced, the adverse effects of the piled excavated materials on regional land productivity, ecological environment, river water quality, and residents' production and life are reduced, and the social, economic and environmental benefits of the project are fully realized.

[0200] The reservoir capacity between the initial operation water level intervals of the upper and lower reservoirs is greater than the required reservoir capacity for power generation. In order to flexibly exchange water quantity between the storage reservoir and the main line canal, it is necessary to ensure stable operation of the unit and to simultaneously raise and lower the water level of the upper and lower reservoirs to expand the water level operation interval of the storage reservoir power station.

[0201] In the scenario of the upper and lower reservoirs being used as water supply reservoirs and cooperating with pumped storage power stations, the water supply reservoirs usually shoulder multiple functions such as regional water supply and flood control. Because they need to meet the long-term water demand in a large area and respond to sudden conditions such as floods, they often have a large reservoir capacity.

[0202] The demand for reservoir capacity of pumped storage power stations mainly focuses on the storage and release of electric energy during peak and valley periods of electricity. In the power generation condition, the water in the upper reservoir flows to the lower reservoir through the pump-turbine to generate electric energy. In the pumping condition, the water in the lower reservoir is pumped back to the upper reservoir to store energy. Because the operation cycle of the pumped storage power station is relatively short, it is usually adjusted in hours or days to meet the demand and supply of electricity. Compared with the long-term water supply demand of the water supply reservoir, the required reservoir capacity is smaller. Even for large pumped storage power stations, the total reservoir capacity of the upper and lower reservoirs is usually in the tens of millions of cubic meters, which is much smaller than the reservoir capacity of large water supply reservoirs.

[0203] When the lower reservoir needs to supply water to the surrounding projects, the water level operation range of the lower reservoir increases to meet the water supply requirements. Due to the limitation of the unit head amplitude, the water level operation range of the upper reservoir decreases, and the water quantity is supplemented from the upper reservoir to the lower reservoir in time.

[0204] Further, when the upper reservoir continuously supplies water to supplement the water quantity of the lower reservoir, the water level operation range of the upper reservoir increases. Due to the limitation of the unit head amplitude, the water level operation range of the lower reservoir decreases.

[0205] Specifically, the water level operation ranges of the upper and lower reservoirs need to meet the maximum head amplitude allowed by the unit:

[0206] △H min,limit = H up,min - H down,max

[0207] △H max,limit = H up,max - H down,min

[0208] △H limit = △H max,limit - △H min,limit ≥ △H

[0209] Wherein, H down,min and H down,max are the minimum and maximum water levels of the lower reservoir under the conditions of meeting the water supply and the limitation of the unit head amplitude, H up,min and H up,max are the minimum and maximum water levels of the upper reservoir under the conditions of meeting the water supply and the limitation of the unit head amplitude, △H min,limit and △H max,limit are the minimum and maximum head amplitudes allowed by the unit during operation, and △H limit is the maximum head amplitude allowed by the unit.

[0210] Since the water supply of the upper and lower reservoirs is a linkage process, a double-reservoir nonlinear coupling equation considering the water supply demand is established.

[0211] Further, when the lower reservoir needs to supply water to the surrounding water trunk, the water level of the lower reservoir changes as follows:

[0212]

[0213] Wherein, Q supply is the water supply flow, A down is the average water surface area of the lower reservoir, is the water level before the change of the lower reservoir, is the water level after the change of the lower reservoir, and △t is the water supply time.

[0214] At this time, the minimum operating water level of the lower reservoir decreases due to the water supply to the peripheral water supply pipeline, resulting in a water head amplitude exceeding the maximum water head amplitude allowed by the unit, that is, ΔH limit <△H, the maximum operating water level of the upper reservoir needs to be reduced, and water is discharged from the upper reservoir to the lower reservoir in time to compensate, and a real-time compensation flow calculation formula is developed:

[0215]

[0216] Wherein, Q comp is the compensation flow, A up is the average water surface area of the upper reservoir, is the water level before compensation of the upper reservoir.

[0217] When the upper reservoir continuously supplies water to the lower reservoir to supplement the water volume, the minimum operating water level of the upper reservoir decreases, resulting in a water head amplitude exceeding the maximum water head allowed by the unit, that is, ΔH limit <△H, the maximum operating water level of the lower reservoir needs to be reduced.

[0218] This is a constantly changing process that requires timely detection of water level changes and dynamic regulation of water level according to the maximum and minimum water head amplitude to smoothly discharge water to meet the water demand of water users.

[0219] According to the principle of first supplying water to the peripheral water supply project from the lower reservoir and then supplying water to the lower reservoir from the upper reservoir, the water level is controlled according to the water head amplitude of the unit to achieve the purpose of supplying water to the peripheral water supply project and meet the function of operating the pumping storage unit to generate electricity.

[0220] According to the characteristics of the constantly changing water level, an adaptive safety boundary calculation method based on the performance curve of the unit is proposed:

[0221] △H safe = f(η(t), P(t), Q(t), T(t))

[0222] Wherein, f() is an adaptive safety boundary function based on the performance curve of the unit; ΔH safe is the set safety water head allowance, η(t) is the real-time efficiency coefficient of the unit, P(t) is the output power of the pumping storage unit, Q(t) is the flow through the pumping storage unit, and T(t) is the water temperature environmental parameter. Used to ensure that the unit operates in a stable and efficient range.

[0223] Further, according to the water head amplitude range allowed by the unit, combined with the actual operation of the power station, the water level change is divided into three gears: normal operation gear, warning gear and emergency control gear.

[0224] Under the normal operation gear, the water head difference ΔH satisfies:

[0225] △H min,limit +△H safe≤△H≤△H max,limit -△H safe

[0226] wherein, △H safe is the set safety water head margin, used to ensure the unit runs in stable and efficient interval. In this gear, the water level of upper and lower reservoirs can be adjusted according to the conventional scheduling strategy, and the water supply and power generation demand are prioritized.

[0227] In the early warning gear, the water head difference ΔH satisfies:

[0228] △H min,limit ≤△H<△H min,limit +△H safe

[0229] or△H max,limit -△H safe <△H≤△H max,limit

[0230] At this time, close attention should be paid to the water level change, and the reservoir water quantity scheduling strategy should be adjusted to prioritize the safe and stable operation of the unit while trying to meet the water supply demand.

[0231] In the emergency control gear, the water head difference ΔH satisfies:

[0232] △H<△H min,limit or△H>△H max,limit

[0233] At this time, immediate emergency measures should be taken to quickly adjust the water exchange between the upper and lower reservoirs, prioritize the safety of the unit, and suspend part of the non-critical water supply tasks to avoid damage to the unit or system failure.

[0234] The above dynamic control process is shown in Figure 2 , with the help of intelligent monitoring system to monitor water level change in real time, calculate △H, judge the gear of current water level change, and dynamically schedule water quantity according to the water level change gear. After completing the control, return to the real-time monitoring step, continue to circulate, ensure that the water level of the power station is always within a reasonable range, ensure the safe and stable operation of the power station, and realize the comprehensive benefits of multiple tasks.

[0235] Further, to realize the above dynamic control process, a multi-objective optimization algorithm considering water supply, power generation, and ecological benefits is proposed, taking water supply, power generation, and ecological benefits as objective functions, taking water level, water head, flow, and water quantity balance as constraint conditions, using genetic algorithm for iterative calculation, and outputting the Pareto optimal solution set meeting the water supply, power generation, and ecological benefits. The algorithm flow chart is shown in Figure 3 .

[0236] First, define a set of decision variables, represented as:

[0237] [△Hup , ΔH down , Q gen , Q pump , Q supply ]

[0238] where ΔH up and ΔH down are the water level changes of the upper reservoir and the lower reservoir, Q gen is the power generation flow, Q pump is the pumping flow, and Q supply is the water supply flow.

[0239] Secondly, the objective function is defined as follows:

[0240] The water supply benefit objective B water is related to the water supply flow and the water supply reliability, and is expressed as:

[0241] B water = k1 x Q supply x R supply

[0242] where k1 is the water supply benefit coefficient, R supply is the water supply reliability, and the value range is [0, 1].

[0243] The power generation benefit objective B power is related to the power generation power and the power generation time length. The power generation power is:

[0244] P gen = η x p x g x Q gen x ΔH

[0245] and the B power = k2 x P gen x t gen

[0246] where k2 is the power generation benefit coefficient, t gen is the power generation time length, P gen is the power generation power; η is the total efficiency of the pumping and storage unit, p is the density of water, and g is the acceleration of gravity.

[0247] The ecological benefit objective B eco is related to the satisfaction degree of the ecological flow, and is expressed as:

[0248]

[0249] where k3 is the ecological benefit coefficient, Q eco is the ecological flow demand, and Q actual is the actual provided ecological flow.

[0250] Considering the water level, water head, flow and water balance requirements in actual operation process, the constraint conditions are determined as follows:

[0251] Water level constraint:

[0252] H up,min ≤H up ≤H up,max , H down,min ≤H down ≤H down,max

[0253] Wherein H up and H down are the water level of upper reservoir and lower reservoir.

[0254] Water head constraint:

[0255] △H min,limit ≤△H≤△H max,limit

[0256] Flow constraint:

[0257] 0≤Q gen ≤Q gen,max

[0258] 0≤Q pump ≤Q pump,max

[0259] Q supply,min ≤Q supply ≤Q supply,max

[0260] Q eco,min ≤Q eco ≤Q eco,max

[0261] Wherein: Q gen,max is the upper limit of power generation flow; Q pump,max is the upper limit of pumping flow; Q supply,min and Q supoly,max are the lower limit and upper limit of water supply flow respectively; Q eco,min and Q eco,max are the lower limit and upper limit of ecological flow demand respectively;

[0262] Water balance constraint: according to the water balance equation of reservoir △V = Q in ·△t-Q out ·△t, ensure that the change of water volume of upper and lower reservoirs meets the actual situation. Wherein, △V is the water volume of reservoir; Q in and Q out are the inflow and outflow of reservoir respectively;

[0263] According to water supply, power generation, ecological benefits, the water supply-power generation-ecological benefit balance index is proposed:

[0264] EBI=(B water / B water-max )^β×(B power / B power-max )^γ×(B eco / B eco-max )^(1-β-γ)

[0265] Wherein: B water-max , B power-max , B eco-max , respectively, the maximum water supply benefit, the maximum power generation benefit and the maximum ecological benefit; β and γ, respectively, the water supply benefit weight and the power generation benefit weight;

[0266] Further, according to the comprehensive utilization method, the following scheduling operation principles are formulated:

[0267] According to the principle of "electricity regulation subject to water regulation", the water supply requirements of the surrounding areas of the project are prioritized, while the safe and stable operation of the power grid is ensured.

[0268] According to the inflow and water regime prediction, the water storage and supply time and water quantity are determined in advance, and the water storage and supply plan is formulated.

[0269] According to the inflow of the water supply reservoir and the water demand of the water receiving area, the water supply emergency plan is formulated to deal with the sudden water supply safety accidents caused by serious water pollution or other major safety accidents.

[0270] For water supply regulation, the following principles are formulated:

[0271] When the water receiving area needs the water supply reservoir to store and supply water interannually or within a year, water is discharged from the upper reservoir to the lower reservoir through the diversion tunnel, and the water of the lower reservoir is supplied to the local water supply main through the culvert.

[0272] For water replenishment operation, when the water storage reservoir needs to be replenished, water is transported from the water distribution main to the lower reservoir through the connecting pipeline, and then pumped from the lower reservoir to the upper reservoir through the diversion tunnel.

[0273] For power generation regulation, the following principles are formulated:

[0274] After the construction of pumped storage power station, it mainly undertakes the tasks of system peak regulation, valley filling, frequency regulation, phase regulation and emergency backup in the power grid.

[0275] For peak regulation operation, pumped storage power station generates power during the peak of the power grid system, solving the problem of power system peak regulation.

[0276] For valley filling operation, pumped storage power station generally pumps water during the low load period of the power system.

[0277] For frequency modulation operation, due to the flexible operation of pumped storage power station, the load can be quickly increased or decreased, and after being put into operation, the load operation can be tracked according to the change of system frequency, so that the system frequency is ensured to be within the allowable range, and the power supply quality of the entire power system is improved.

[0278] For phase modulation operation, the pumped storage power station not only can send active power, but also has the function of phase modulation. In any operating condition, the system reactive power can be adjusted by changing the excitation current. The system reactive power deficiency can be made up, and the system reactive power surplus can be eliminated. Especially when the system reactive power is surplus, the pumped storage power station can operate in phase modulation mode to absorb the system reactive power, thereby reducing the system voltage and ensuring the system voltage within the normal range.

[0279] For emergency standby, when the pumped storage power station operates normally in the normal operating water level range of the upper and lower reservoirs, if an accident occurs in the power system, the unit not carrying full load can be used to send emergency power to replace the unit stopped due to failure in the system in the power generation condition. In the pumping condition, the entire unit can be withdrawn from the pump operation according to the system needs to reduce the load of the power grid, play the role of emergency standby, and in a short time, the unit can be converted to power generation operation and bear the emergency standby. In the static condition, the unit can be started for power generation in emergency.

[0280] The application constructs a water supply reservoir and pumped storage power station cooperative operation system, realizes double breakthroughs of comprehensive utilization of water resources and efficient conversion of energy, on the basis of meeting the safety of urban water supply, through intelligent monitoring and dynamic water level regulation strategy, the unit operation efficiency is ensured, the excavated material of the upper and lower reservoirs of the pumped storage power station is used as building aggregate, the problems of land occupation and ecological destruction of traditional engineering waste slag are effectively solved, through a multi-objective genetic algorithm optimization scheduling model, dynamic balance of water supply, power generation and ecological benefits is realized, while guaranteeing the daily water supply capacity of the water transfer project, the construction conditions and advantages of the pumped storage power station are fully tapped, the peak shaving and valley filling capacity of the power grid is improved, and the safe and stable operation of the power grid is ensured, the application breaks through the limitation of single engineering function, provides an innovative solution for the water resource-energy-ecological coupling system, and has remarkable engineering application value and social and economic benefits.

[0281] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the art, without departing from the principles of the application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the application.

Claims

1. A low-head high-amplitude pumped storage power station multi-task comprehensive utilization method, characterized in that, The method comprises the following steps: Step S1, building aggregate supply: processing the earthwork excavated from the upper reservoir and the lower reservoir as building aggregate to supply to the surrounding projects; Step S2, the upper reservoir and the lower reservoir have the functions of water supply and guaranteeing the operation of the pumping and storage unit; specifically, the water level changes of the upper reservoir and the lower reservoir are monitored in real time through an intelligent monitoring system to obtain the water head difference ΔH; the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head difference ΔH to preferentially meet the water supply requirements of the surrounding areas, while the safe and stable operation of the power grid is guaranteed as much as possible; When the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head difference ΔH, a multi-objective optimization algorithm based on a genetic algorithm is adopted, the water supply, power generation and ecological benefits are taken as objective functions, the water level, water head, flow and water quantity balance are taken as constraint conditions, and the Pareto optimal solution set meeting the water supply, power generation and ecological benefit targets is output through iterative calculation; The multi-objective optimization algorithm based on the genetic algorithm outputs the Pareto optimal solution set meeting the water supply, power generation and ecological benefit targets, and specifically comprises the following steps: Step A1, a group of decision variables is defined and represented as: ; wherein, and are the water level change amounts of the upper reservoir and the lower reservoir, respectively, is the power generation flow rate, is the pumping flow rate, is the water supply flow rate; Step A2, the objective functions and constraint conditions are defined as follows: Water supply efficiency target : related to water supply flow and water supply reliability, expressed as: ； wherein: is a water supply efficiency coefficient, is a water supply reliability, taking a value in the range [0, 1]; Generation benefit targets : related to power and duration of generation: ； ； wherein: is the power generation benefit coefficient, is the power generation duration, is the power generation power; is the total efficiency of the pumped storage unit, is the density of water, is the acceleration due to gravity; Ecological benefit objective : related to the degree of satisfaction of the ecological flow, expressed as: ； wherein: is the ecological benefit coefficient, is the ecological flow demand, is the actual provided ecological flow; Considering the water level, water head, flow and water quantity balance requirements in the actual operation process, the constraint conditions are determined as follows: Water level constraint: ， ； wherein: and are the upper and lower reservoir water levels, respectively; Water head constraint: ； Flow constraint: ； ； ； ； wherein: is an upper limit on the power generation flow rate; is an upper limit on the pumping flow rate; and are, respectively, a lower limit and an upper limit on the water supply flow rate; and are, respectively, a lower limit and an upper limit on the ecological flow demand; Water balance constraint: according to the water balance equation of the reservoir , ensure that the water volume change of the upper and lower reservoirs conforms to the actual situation; wherein, is the water volume of the reservoir; and , respectively, are the inflow and outflow of the reservoir. According to water supply, power generation, ecological benefits, water supply-power generation-ecological benefit balance index is proposed : ； wherein: , , , are the maximum water supply benefit, the maximum power generation benefit and the maximum ecological benefit, respectively; and are the water supply benefit weight and the power generation benefit weight, respectively. Step A3, the genetic algorithm is adopted to solve the objective functions to obtain the optimal solution set of the decision variables.

2. The multi-task comprehensive utilization method of low-head high-amplitude pumped storage power station according to claim 1, characterized in that, Step S2 specifically comprises: Step S2.1, according to the water head amplitude range allowed by the pumping and storage unit, the water level change is divided into three gears: a normal operation gear, a pre-warning gear and an emergency control gear; Step S2.2, the current water level change belongs to which gear is determined according to the water head difference ΔH; Under the normal operation gear, the water head difference ΔH satisfies: ； wherein: is a set safety head margin for ensuring the pumped storage unit operates in a stable and efficient range; and are the minimum and maximum water heads allowed for the pumped storage unit to operate, respectively. Under the pre-warning gear, the water head difference ΔH satisfies: ； or ; Under the emergency control gear, the water head difference ΔH satisfies: or ; Step S2.3, according to the gear where the current water level change is located, the corresponding reservoir water quantity scheduling strategy is executed: If it is the normal operation gear, the current operation state is maintained, and the water levels of the upper reservoir and the lower reservoir are adjusted according to the conventional scheduling strategy to preferentially meet the water supply and power generation demands; If it is the pre-warning gear, the water level changes of the upper reservoir and the lower reservoir are closely observed, the reservoir water quantity scheduling strategy is adjusted, the safe and stable operation of the pumping and storage unit is preferentially guaranteed, and the water supply demand is as much as possible satisfied; If it is the emergency control gear, immediate emergency measures need to be taken to quickly adjust the water quantity exchange between the upper reservoir and the lower reservoir, the safety of the pumping and storage unit is preferentially guaranteed, part of the non-key water supply tasks are suspended, and the damage or system failure of the pumping and storage unit is avoided.

3. The multi-task comprehensive utilization method of low-head high-amplitude pumped storage power station according to claim 2, characterized in that, Set safety head margin The following adaptive safety margin formula based on unit performance curve is used to determine: ； wherein: is an adaptive security boundary function based on the unit performance curve; is the real-time efficiency coefficient of the pumped storage unit, is the output power of the pumped storage unit, is the flow rate through the pumped storage unit, is the water temperature environmental parameter.

4. The multi-task comprehensive utilization method of low-head high-amplitude pumped storage power station according to claim 2, characterized in that, The upper reservoir and the lower reservoir water level operation range needs to meet the maximum water head amplitude allowed by the pumping and storage unit: ； ； ； wherein: and are the minimum and maximum water levels of the lower reservoir under the head variation limit of the water supply and pumping storage unit; and are the minimum and maximum water levels of the upper reservoir under the head variation limit of the water supply and pumping storage unit; and are the minimum and maximum water heads allowed when the pumping storage unit is operating; is the maximum water head allowed for the pumping storage unit.

5. The multi-task comprehensive utilization method of low-head high-amplitude pumped storage power station according to claim 2, characterized in that, When the lower reservoir needs to supply water to the surrounding water trunk, the water level change of the lower reservoir is: ； wherein: is the water supply flow rate, is the average water surface area of the lower reservoir, is the water level of the lower reservoir before the change, is the water level of the lower reservoir after the change, is the water supply time; At this time, the minimum operating water level of the lower reservoir decreases due to supplying water to the peripheral water supply pipeline, causing the water head amplitude to exceed the maximum water head amplitude allowed by the pumping and storage unit, i.e. , the maximum operating water level of the upper reservoir needs to be reduced, and water is discharged from the upper reservoir to the lower reservoir in time for compensation, and a real-time compensation flow calculation formula is adopted: ； wherein: is the compensation flow rate, is the average water surface area of the upper reservoir, is the water level of the upper reservoir before compensation; When the upper reservoir continuously supplies water to the lower reservoir to replenish the water, the minimum operating water level of the upper reservoir decreases, causing the water head amplitude to exceed the maximum water head allowed by the pumping and storage unit, i.e. , the maximum operating water level of the lower reservoir needs to be reduced; Therefore, by detecting the water level changes of the upper reservoir and the lower reservoir, the water level is dynamically controlled according to the maximum and minimum water head amplitude, and the water is smoothly discharged to meet the water demand of the water users.

6. The multi-task comprehensive utilization method of low-head high-amplitude pumped storage power station according to claim 1, characterized in that, When the water quantity of the upper reservoir and the lower reservoir is dynamically scheduled according to the water head difference ΔH, the following scheduling operation principles are adopted: Comprehensive scheduling operation principle: According to the principle of water regulation priority, the water supply requirements of the surrounding areas of the project are met, and the safe and stable operation of the power grid is ensured as much as possible; According to the inflow and water regime prediction, the time and water volume of regulation and storage water supply are determined in advance, and the regulation and storage water supply plan is formulated; According to the inflow of the upper reservoir and the lower reservoir and the water demand of the water receiving area, an emergency plan for water supply is formulated to deal with the sudden water supply safety accidents caused by serious water pollution or other major safety accidents; Water supply regulation principles: When the water receiving area needs the upper reservoir and the lower reservoir to store water for inter-annual or intra-annual water supply, water is discharged from the upper reservoir to the lower reservoir through the diversion tunnel, and the water in the lower reservoir is supplied to the surrounding water distribution main through the connecting pipeline; For water replenishment operation, when the upper reservoir and the lower reservoir need to be replenished, water is transported from the surrounding water distribution main to the lower reservoir through the connecting pipeline, and then pumped from the lower reservoir to the upper reservoir through the diversion tunnel; Power generation regulation principles: After the construction of the pumped storage power station, it undertakes the tasks of system peak regulation, valley filling, frequency regulation, phase regulation and emergency standby in the power grid; For peak regulation operation, the pumped storage power station generates power during the power system peak load to solve the problem of power system peak regulation; For valley filling operation, the pumped storage power station pumps water during the low load of the power system; For frequency regulation operation, due to the flexible operation of the pumped storage power station and the fast speed of load increase and decrease, after being put into operation, it tracks the load operation according to the change of system frequency to ensure that the system frequency is within the allowed range and improve the power supply quality of the entire power system; For phase regulation operation, the pumped storage power station not only can output active power, but also has the function of phase regulation. No matter in which working condition, it can adjust the reactive power output of the system by changing the excitation current; It can not only make up for the lack of reactive power of the system, but also eliminate the excess of reactive power of the system. Especially when the system has excess reactive power, the pumped storage power station can operate in phase regulation mode to absorb the reactive power in the system, thereby reducing the system voltage and ensuring that the system voltage is within the normal range; For emergency standby, when the power system fails, the pumped storage power station can use the non-full load unit to generate emergency power to replace the units that are out of operation due to system failure in the power generation condition; In the pumping condition, it can exit the pump operation according to the system needs to reduce the load of the power grid, play the role of emergency standby, and can be converted to power generation operation in a short time and undertake the task of emergency standby; In the static working condition, it can start to generate power in an emergency.

7. The multi-task comprehensive utilization method of low-head high-amplitude pumped storage power station according to claim 1, characterized in that, The low-head high-amplitude pumped storage power station multi-task comprehensive utilization method is applied to a low-head high-amplitude pumped storage power station multi-task comprehensive utilization system; The low-head high-amplitude pumped storage power station multi-task comprehensive utilization system comprises an upper reservoir, a lower reservoir, a diversion tunnel, a pumped storage unit, a connecting pipeline and a surrounding water distribution main; The upper reservoir provides online regulation and storage and water supply for the surrounding water distribution project, and the excavated material during the construction process is used for the supply of building aggregates in the surrounding areas; The lower reservoir provides online regulation and storage and water supply for the surrounding water distribution project, and the excavated material during the construction process is used for the supply of building aggregates in the surrounding areas; The diversion tunnel is connected between the upper reservoir and the lower reservoir and is used for mutual supplement of water between the upper reservoir and the lower reservoir. The pumping and storing unit is arranged between the upper reservoir and the lower reservoir, and a reversible pump-turbine unit of the pumping and storing unit is used for supplement of water, energy dissipation and power generation through the diversion tunnel; specifically, the pumping and storing unit is used for converting energy of water flow between the upper reservoir and the lower reservoir into mechanical energy, and is used for driving various mechanical equipment or generating power. The connecting pipeline is connected with the lower reservoir and the peripheral water distribution main line respectively and is used for mutual supplement of water between the lower reservoir and the peripheral water distribution main line.

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