Reservoir group water supply optimization scheduling method

Abstract

The invention discloses a reservoir group water supply optimization scheduling method, which comprises the following steps: equivalently transforming a reservoir group water supply optimization objective function and constraint conditions into a linear model, and simultaneously obtaining multi-reservoir group collaborative optimal water supply scheduling parameters by using a linear solver. The method has no special requirements on factors such as reservoir quantity, user quantity, water delivery line arrangement, and geographical environment of a basin or a region, is wide in application range, is convenient to calculate, is not influenced by a topological relation between reservoirs, and can effectively improve the working efficiency of water resource development, utilization and management.

Description

Technical Field

[0001] The invention relates to the technical field of reservoir dispatching, and is particularly applicable to a method for optimizing the dispatching of water supply of a reservoir group. Background Art

[0002] The optimal dispatching of water supply of a reservoir group is a non-engineering means of regulating the natural runoff process of a river. Its main function is to adjust the surplus water in the flood season or flood year to the dry season or dry year, or to divert (adjust) the surplus water in the water-rich area to the water-scarce area, so as to achieve the reasonable allocation of water resources in time and space. The essence of the optimal dispatching of water supply of a reservoir group is to study the relationship between incoming water, water use, reservoir regulation capacity and guarantee rate, and to achieve the storage of abundant water resources and the replenishment of scarce water resources through the storage and discharge dispatching of the reservoir group.

[0003] The optimized dispatching of water supply of reservoir groups is mainly applied in two aspects. One is to determine the scale of the project in the early demonstration stage of water diversion and regulation projects. The other is to optimize the dispatching and operation mode of reservoir water supply in the reservoir dispatching and operation stage.

[0004] Actual water supply projects usually have the characteristics of non-unique water supply objects, non-unique water sources, and different water supply guarantee rates. This determines that the water supply dispatching of a reservoir group is a multi-objective, multi-constrained, nonlinear optimization problem, so the modeling is complex and difficult to solve. At present, the country has not issued relevant standards and specifications for the optimal dispatching method of water supply of a reservoir group. Only the principles and ideas for the calculation of runoff regulation of a single reservoir are given in the "Hydraulic Calculation Specifications for Water Conservancy Projects" (SL 104-2015), and no specific calculation steps are given, nor does it involve the joint dispatching of reservoir groups. Therefore, it is impossible to effectively guide the preliminary demonstration and dispatching operation of water supply projects. Summary of the invention

[0005] The present invention aims to provide a method for optimizing the water supply scheduling of a reservoir group, so as to solve the problem of the current lack of a method for optimizing the water supply scheduling by regulating runoff from multiple reservoirs.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The reservoir group water supply optimization scheduling method described in the present invention is based on the network topology of the water resource system in the scheduling area, with the goal of maximizing the total water supply of the water resource system in the scheduling area during the calculation period. It constructs the objective function and the water level constraints of each node in the network topology of the water resource system in the scheduling area during the calculation period, the upper limit constraints of the outflow flow, the water supply constraints of the water supply object, the water supply guarantee rate constraints, and the maximum water supply damage depth constraints. After the water supply guarantee rate constraints are linearized based on the principle of equivalent transformation, the scheduling parameters of each node are determined using a linear solver.

[0007] Furthermore, the objective function is , where I, i are the total number and serial number of reservoirs; J, j are the total number and serial number of users; T, t are the total number and serial number of calculation periods; S i,j,t is the amount of water supplied from reservoir i to user j during period t.

[0008] Furthermore, the water level constraint condition of each node is: , where Z i,t , Z min,i,t , Z max,i,t are the operating water level, minimum operating water level and maximum operating water level of reservoir i in period t; the minimum operating water level is the dead water level, the maximum operating water level is the flood limit water level in the flood season and the normal water storage level in the non-flood season, and the operating water level is the planned operating water level.

[0009] Furthermore, the upper limit constraint condition of the outbound flow is: , where Q i,t , Q max,i,t is the outflow and maximum outflow of reservoir i in period t.

[0010] Furthermore, the water supply quantity constraint condition of the water supply object is: , where R j,t is the water demand of user j in period t, S i,j,t is the amount of water supplied from reservoir i to user j during period t.

[0011] Furthermore, the maximum damage depth constraint condition of water supply is: , where E out,j,t E is the maximum damage depth allowed for water supply to user j during period t; in,i,t It is the maximum damage depth allowed by the ecological flow under the dam of reservoir i during period t.

[0012] Furthermore, the water supply guarantee rate constraint condition includes the water supply guarantee rate outside the river channel and the ecological flow guarantee rate inside the river channel; the water supply guarantee rate constraint condition outside the river channel is , ; The constraint condition of ecological flow guarantee rate in the river is , ; where U out,j,t P is the water supply guarantee rate judgment variable for users outside the river during period t, and its value is 0 or 1, where 0 means that the water supply guarantee rate is not met and 1 means that the water supply guarantee rate is met; out,j Water supply guarantee rate for users outside the river; U in,i,t is the judgment variable of the ecological flow guarantee rate under the dam of reservoir i in period t, with a value of 0 or 1, 0 means that the ecological flow guarantee rate is not met, and 1 means that the ecological flow guarantee rate is met; P in,i is the ecological flow guarantee rate below the dam of reservoir i; Q st,i,t is the ecological flow downstream of reservoir i; S i,j,tis the water supply from reservoir i to user j during period t; R j,t is the water demand of user j in period t; Q i,t is the outflow from reservoir i during period t.

[0013] Furthermore, the water supply guarantee rate constraint condition is linearized as follows: , , , where k=1,2,3,4, a k The value is 0 or 1, and the value ranges of C1, C2, C3, and C4 are [0, R j,t ), [R j,t ,R j,t ]、[0,Q st,i,t ), [Q st,i,t ,Q st,i,t ]; C min,k , C max, k C k The minimum and maximum values ​​of .

[0014] The advantage of the present invention is that the objective function and constraint conditions of water supply optimization of a reservoir group are equivalently transformed into a linearized model, and the optimal water supply scheduling parameters of a multi-reservoir group are obtained simultaneously by using a linear solver. It has no special requirements on factors such as the number of reservoirs, the number of users, the layout of water transmission lines, the river basin or regional geographical environment, etc. It has a wide range of applications and is easy to calculate. It is not affected by the topological relationship between reservoirs and can effectively improve the efficiency of water resources development, utilization and management. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the outflow and inflow of nodes in the water resource system network topology.

[0016] Figure 2 It is a simple schematic diagram of the water resource system network topology.

[0017] Figure 3 It is a schematic diagram of the process of the method of the present invention.

[0018] Figure 4 It is a schematic diagram of the layout of a certain project in the present invention.

[0019] Figure 5 It is a network topology diagram of a water resource system of a certain project in the present invention. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The method for optimizing the water supply scheduling of a reservoir group of the present invention is based on the network topology of the water resource system in the scheduling area, takes the maximum total water supply of the water resource system in the scheduling area during the calculation period as the goal, constructs the objective function and the water level constraints of each node in the network topology structure of the water resource system in the scheduling area during the calculation period, the upper limit constraints of the outflow flow, the water supply quantity constraints of the water supply object, the water supply guarantee rate constraints, and the maximum damage depth constraints of the water supply. After the water supply guarantee rate constraints are linearized based on the principle of equivalent transformation, a linear solver is used to determine the scheduling parameters of each node.

[0022] Among them, the network topology of the water resource system is composed of nodes and lines. Nodes represent input water volume, output water volume, water storage volume, etc., and lines represent the direction of water flow. For the water resource system, nodes can correspond to reservoirs, water distribution hubs, control sections, water plants, water users, etc., among which reservoirs have water storage capacity and water distribution hubs have regulating pools, both of which have certain regulating and storage capabilities, and the water storage volume can change; lines can correspond to rivers, channels, tunnels, pipelines, etc., and the water storage volume of the lines is generally set to a constant value or 0. Nodes and lines follow the principle of water balance to form a water supply and demand network.

[0023] like Figure 1 , Figure 2 As shown, Figure 1 middle, R 上游 , R 区间 , R 退水 , R 地表 , R 地下 , R 其他 Node i The outflow volume, interval water volume, and retreat volume of the upstream adjacent nodes, local surface water volume, groundwater volume, and other water volume (recycled water, collected rainwater, desalinated water, etc.) are all nodes. i The amount of water input; C 下游 , C 退水 , C 损失 , C 生活 , C 工业 , C农业 , C 生态 Node i The inflow, return, and loss of the downstream adjacent nodes, as well as the node life, industry, agriculture, and ecological water supply are all node i Output water volume; S 时段初 , S 时段末 Node i Water storage at the beginning and end of the time period. Figure 2 middle, R 节点i For connection ij Upstream Node i The outflow volume (input volume); C 损失 , C 节点j Separately connect ij Water loss, downstream nodes j The inflow water volume (output water volume); connection line ij The arrows indicate the direction of water flow.

[0024] The network topology of the water resource system in the dispatching area consists of many such nodes and lines. The principle of optimal dispatching of water supply of a reservoir group is to fully tap the water supply potential of the reservoir group under the premise of meeting the water supply guarantee rate and maximum damage depth of each water supply object. Therefore, the objective function is constructed with the goal of maximizing the total water supply of the water resource system in the dispatching area during the calculation period, as shown in formula (1).

[0025] Formula (1) Where I, i are the total number and serial number of reservoirs; J, j are the total number and serial number of users; T, t are the total number and serial number of calculation periods; S i,j,t is the amount of water supplied from reservoir i to user j during period t, in ten thousand cubic meters.

[0026] At the same time, water level constraints for each node in the water resource system network topology structure in the scheduling area during the calculation period, outflow flow upper limit constraints, water supply quantity constraints for water supply objects, water supply guarantee rate constraints, and maximum water supply damage depth constraints are constructed.

[0027] The water level constraints of each node are shown in formula (2).

[0028] Formula (2) Where Z i,t , Z min,i,t , Z max,i,tis the operating water level, minimum operating water level and maximum operating water level of reservoir i in period t, in meters; the minimum operating water level is the dead water level, the maximum operating water level is the flood limit water level in the flood season and the normal water storage level in the non-flood season, and the operating water level is the planned operating water level.

[0029] The upper limit constraint of outbound flow is shown in formula (3).

[0030] Formula (3) Where Q i,t , Q max,i,t is the outflow and maximum outflow of reservoir i during period t, in m 3 / s.

[0031] The water supply constraint condition of the water supply object is shown in formula (4).

[0032] Formula (4) Where R j,t is the water demand of user j in period t, S i,j,t is the amount of water supplied from reservoir i to user j during period t, in ten thousand cubic meters.

[0033] The water supply guarantee rate constraints include the water supply guarantee rate constraints outside the river channel and the ecological flow guarantee rate constraints within the river channel.

[0034] The constraint condition of water supply guarantee rate outside the river is shown in formula (5).

[0035] Formula (5) in, Formula (6) The constraint condition of the ecological flow guarantee rate in the river is shown in formula (7).

[0036] Formula (7) in, Formula (8) In the above formula (5)-formula (8), U out,j,t P is the water supply guarantee rate judgment variable for users outside the river during period t, and its value is 0 or 1, where 0 means that the water supply guarantee rate is not met and 1 means that the water supply guarantee rate is met; out,j Water supply guarantee rate for users outside the river; U in,i,t is the judgment variable of the ecological flow guarantee rate under the dam of reservoir i in period t, with a value of 0 or 1, 0 means that the ecological flow guarantee rate is not met, and 1 means that the ecological flow guarantee rate is met; P in,i is the ecological flow guarantee rate below the dam of reservoir i; Q st,i,t is the ecological flow downstream of reservoir i, in m 3 / s;Si,j,t is the water supply from reservoir i to user j during period t; R j,t is the water demand of user j in period t; Q i,t is the outflow from reservoir i during period t, in m 3 / s.

[0037] Finally, the maximum damage depth constraint of water supply is shown in formula (9).

[0038] Formula (9) The depth of water supply damage refers to the ratio of water shortage to water demand of the water supply object, which is used to describe the degree of damage to the water supply task. out,j,t E is the maximum damage depth allowed for water supply to user j during period t; in,i,t It is the maximum damage depth allowed by the ecological flow under the dam of reservoir i during period t. E out,j,t The value is between 0 and 1.

[0039] It can be seen from the reservoir group water supply optimization scheduling model composed of the above objective functions and constraints that the water supply guarantee rate constraint conditions, including the water supply guarantee rate constraint conditions outside the river channel and the ecological flow guarantee rate constraint conditions inside the river channel, are piecewise functions, and other constraints and objective functions are all linear functions.

[0040] In the prior art, there are only single-reservoir runoff regulation calculation methods and processes. In the face of joint water supply optimization scheduling involving multiple reservoirs, technical personnel in this field adopt a one-by-one calculation method. That is, according to the upstream and downstream input-output cascade relationship between the reservoirs, according to the single-reservoir runoff regulation calculation method, the water supply scheduling of the upstream reservoir is first obtained, and on this basis, the water supply scheduling of the downstream reservoir is calculated. This is determined by the basic principle that the upstream water supply scheduling will inevitably affect the downstream water supply scheduling. In the water supply optimization scheduling of a reservoir group, the existing calculation methods are used, and the goal is often focused on whether each reservoir in the reservoir group has achieved the optimal water supply scheduling, while ignoring the coordination between the reservoirs. It seems that each small range is optimized, but the large-scale optimization is not achieved, and the efficiency is low.

[0041] The inventor of this application introduced a linear solution to this problem. First, according to the equivalent transformation principle, the piecewise functions of the water supply guarantee rate constraint outside the river channel and the ecological flow guarantee rate constraint inside the river channel are linearized. The processing results are as follows: Formula (10) Formula (11) Formula (12) Among them, k=1,2,3,4 is the auxiliary variable number and has no specific physical meaning.a k , C k , D k They are all intermediate auxiliary variables and have no specific physical meaning. k The value is 0 or 1, and the value ranges of C1, C2, C3, and C4 are [0, R j,t ), [R j,t ,R j,t ]、[0,Q st,i,t ), [Q st,i,t ,Q st,i,t ]; C min,k , C max, k C k The model after linearization is a standard linear programming model, which can be solved by a mature linear solver without considering the influence of the reservoir cascade relationship, so that the same planning and coordinated dispatch of the reservoir group can be achieved. Although it may not be possible to achieve the optimal dispatch of each reservoir, it can provide dispatch efficiency and dispatch effect for the entire region.

[0042] The specific solution process is as follows Figure 3 shown.

[0043] First, a reservoir water supply regulation calculation optimization model is constructed according to the reservoir group water supply optimization dispatching method of the present invention. It is determined whether the model is a linear model. If it is not a linear model, the model is converted into a linear model according to the equivalent transformation principle.

[0044] Then, the model objective is converted into a minimization form, that is, the total water shortage is minimized (total water shortage = total water demand - total water supply), the formula is: , the constraint condition is converted to the form of less than or equal to "≤", that is, the left side of the "≤" inequality sign is the decision variable, and the right side is the constant. For example, the water level constraint condition of each node , after conversion to and The transformation methods of the two inequalities and other constraints are similar and will not be repeated here.

[0045] Next, extract the decision variable coefficient vector in the objective function, the decision variable coefficient matrix and constant vector in the constraint conditions, the upper and lower limits of the decision variables, integers, non-integers and other information.

[0046] (1) Extraction of the coefficient vector of the objective function decision variables: represents the user's water demand, which is a known condition and a constant. represents the water supply, which is the variable that needs to be optimized and is the decision variable. The coefficient of is equal to 1, so the decision variable coefficient vector extracted by the objective function is .

[0047] (2) Extraction of constraint decision variable coefficient vector and constant vector, based on the water level constraint of each node and Take this as an example to illustrate.

[0048] represents the highest operating water level of the reservoir, which is a known condition and a constant. represents the operating water level of the reservoir, which is the variable that needs to be optimized and is the decision variable. The coefficient of is equal to 1, so the constraint The extracted decision variable coefficient vector is , the extracted constant vector is . Water level constraints The method of extracting decision variable coefficient vectors and constant vectors for other constraints is similar and will not be repeated here.

[0049] (3) For the extraction of the upper and lower limit constant vectors of decision variables, the decision variables Take this as an example to illustrate. Indicates the water supply. According to the actual situation, the water supply should be between 0 and the water demand. Therefore, the decision variables extracted The lower limit constant vector of , the upper limit constant vector is The methods for extracting the upper and lower limit constant vectors of other decision variables are similar and will not be described in detail.

[0050] (4) For the extraction of information when the decision variable is an integer or a non-integer, if the decision variable is an integer, the extracted value is 1; if the decision variable is a non-integer, the extracted value is 0.

[0051] Finally, the linear solver is called to perform optimization calculations, and the optimization results are parsed and output in the preset output format.

[0052] The following takes a large-scale inter-basin long-distance water diversion project as an example to illustrate the application process and application effect of the technical solution of the present invention.

[0053] According to the actual situation of the project, first draw a schematic diagram of the project layout, see Figure 4 . Construct the network topology of the project according to the project layout, see Figure 5 . Figure 5 The numbers in the nodes correspond to the node numbers and are used to uniquely identify each node.

[0054] According to the reservoir group water supply optimization scheduling method described in the present invention, the project-related data is collected, substituted into the constructed linear model, and solved using a linear solver. It is calculated that the total adjustable water volume of the 7 water source reservoirs of the project is 500.97 billion m³, and the multi-year average adjustable water volume is 9.109 billion m³, among which the multi-year average adjustable water volume of water source reservoir 1 to water source reservoir 7 is 2.162 billion m³, 370 million m³, 427 million m³, 520 million m³, 412 million m³, 256 million m³, and 4.962 billion m³ respectively. The multi-year average adjustable water volume of each water source reservoir calculated according to the model can further carry out the demonstration of engineering scale indicators such as the characteristic water level of the water source reservoir and the design flow of the water transmission line.

Claims

1. A method for optimizing water supply scheduling of a reservoir group, characterized in that: According to the network topology of the water resources system in the scheduling area, with the goal of maximizing the total water supply of the water resources system in the scheduling area during the calculation period, the objective function and the water level constraints of each node in the network topology of the water resources system in the scheduling area during the calculation period, the upper limit constraints of the outflow flow, the water supply constraints of the water supply objects, the water supply guarantee rate constraints, and the maximum damage depth constraints of the water supply are constructed. After the water supply guarantee rate constraints are linearized based on the principle of equivalent transformation, the scheduling parameters of each node are determined using a linear solver.

2. The method for optimizing water supply and dispatching of a reservoir group according to claim 1, characterized in that: The objective function is , where I, i are the total number and serial number of reservoirs; J, j are the total number and serial number of users; T, t are the total number of calculation periods and the period sequence number; S i,j,t is the amount of water supplied from reservoir i to user j during period t.

3. The method for optimizing water supply and dispatching of a reservoir group according to claim 1, characterized in that: The water level constraints of each node are: , where Z i,t , Z min,i,t , Z max,i,t are the operating water level, minimum operating water level and maximum operating water level of reservoir i in period t; the minimum operating water level is the dead water level, the maximum operating water level is the flood limit water level in the flood season and the normal water storage level in the non-flood season, and the operating water level is the planned operating water level.

4. The method for optimizing water supply and dispatching of a reservoir group according to claim 1, characterized in that: The upper limit constraint condition of the outbound flow is: , where Q i,t , Q max,i,t is the outflow and maximum outflow of reservoir i in period t.

5. The method for optimizing water supply and dispatching of a reservoir group according to claim 1, characterized in that: The water supply constraint condition of the water supply object is: , where R j,t is the water demand of user j in period t, S i,j,t is the amount of water supplied from reservoir i to user j during period t.

6. The method for optimizing water supply and dispatching of a reservoir group according to claim 1, characterized in that: The maximum damage depth constraint condition for water supply is: , where E out,j,t E is the maximum damage depth allowed for water supply to user j during period t; in,i,t It is the maximum damage depth allowed by the ecological flow under the dam of reservoir i during period t.

7. The method for optimizing water supply and dispatching of a reservoir group according to claim 1, characterized in that: The water supply guarantee rate constraint condition includes the water supply guarantee rate outside the river channel and the ecological flow guarantee rate inside the river channel; the water supply guarantee rate constraint condition outside the river channel is: , ; The constraint condition of ecological flow guarantee rate in the river is , ;in; T, t are the total number of calculation periods and the period sequence number; U out,j,t P is the water supply guarantee rate judgment variable for users outside the river during period t, and its value is 0 or 1, where 0 means that the water supply guarantee rate is not met and 1 means that the water supply guarantee rate is met; out,j Water supply guarantee rate for users outside the river; U in,i,t is the judgment variable of the ecological flow guarantee rate under the dam of reservoir i in period t, with a value of 0 or 1, 0 means that the ecological flow guarantee rate is not met, and 1 means that the ecological flow guarantee rate is met; P in,i is the ecological flow guarantee rate below the dam of reservoir i; Q st,i,t is the ecological flow downstream of reservoir i; S i,j,t is the water supply from reservoir i to user j during period t; R j,t is the water demand of user j in period t; Q i,t is the outflow from reservoir i during period t.

8. The method for optimizing water supply and dispatching of a reservoir group according to claim 7, characterized in that: The water supply guarantee rate constraint condition is linearized as follows: , , , where k=1,2,3,4, a k The value is 0 or 1. The value ranges of C1, C2, C3, and C4 are [0, R j,t ), [R j,t ,R j,t ]、[0,Q st,i,t ), [Q st,i,t ,Q st,i,t ]; C min,k , C max, k C k The minimum and maximum values ​​of .

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