A method for generating optimized dispatching scheme for joint flood control of reservoir groups

Abstract

A method for generating a joint flood control optimization scheduling scheme for a reservoir group belongs to the technical field of flood control scheduling for a reservoir group. First, according to the predicted rainfall and the size of the water inflow, combined with the rule scheduling simulation model, the flood control situation in the basin is judged, and the flood control scheduling objectives and needs are determined; secondly, based on different flood control situations and needs, a corresponding joint optimization model for the reservoir group is constructed: for small floods within the downstream standard, a joint optimization model for the reservoir group with the minimum downstream combined flow as the goal is constructed; for floods exceeding the downstream standard, a reservoir group pre-discharge optimization scheduling model is constructed; for large floods, a multi-objective joint scheduling model for the reservoir group that considers the safety of the reservoir itself and the safety of the downstream protection objects is constructed; thirdly, the model is solved to generate scheduling plans under different flood control situations. The present invention can generate scheduling plans that meet flood control needs, is suitable for flood control scheduling of reservoir groups in various basins, and adapts to the current new flood control form needs.

Description

Technical Field

[0001] The invention belongs to the technical field of flood control dispatching of reservoir groups, and relates to a method for generating a joint flood control optimization dispatching plan of a reservoir group. Background Art

[0002] Flood disasters frequently occur in my country, especially in recent years, when extreme rainstorms in some local areas have caused large floods at the basin level. Reservoirs are important engineering measures for flood control in basins. Reservoirs regulate floods through their interception and storage functions. On the premise of ensuring the flood control safety of the reservoirs themselves, flood interception, peak reduction, and peak shifting are carried out to reduce the flood control pressure downstream. In recent years, with the construction of large-scale reservoir groups, major basins have initially built a basin flood control engineering system that matches the main and tributary reservoirs, embankments, and flood storage areas, and gradually formed a joint dispatching pattern of large-scale mixed reservoir groups in the whole basin, jointly ensuring the flood control safety of the downstream areas of the reservoir groups and maximizing the flood control benefits of the basin. However, due to the large number of reservoirs and complex topological relationships, there are also complex hydrological and hydraulic connections between reservoirs. Each reservoir not only has its own flood control tasks, but also undertakes the common flood control tasks of the basin, making it difficult for traditional single reservoir dispatching to meet the existing flood control needs. In order to give full play to the synergy between reservoirs, joint flood control dispatching of reservoir groups is carried out to maximize the flood control benefits of reservoir groups.

[0003] On the basis of single reservoir operation, the joint optimization operation of reservoir groups considers the complex hydraulic connection between reservoirs, clarifies the reservoirs themselves and the common flood control tasks, rationally utilizes the storage capacity of reservoir groups, and reduces the downstream flood control pressure to the greatest extent, so as to maximize the flood control benefits of the basin. Usually, reservoir groups have upstream and downstream flood protection objects, and most of them are optimized operation methods considering a single goal. Chen et al. (Chen H, Wang W, Chau K, et al. Flood Control Operation of Reservoir Group Using Yin-Yang Firefly Algorithm[J]. Water Resources Management, 2021, 35(15): 5325-5345.) studied the joint optimization operation method of the flood control system consisting of reservoirs, rivers, and downstream control points in the Luanhe River Basin with the goal of minimizing the peak flow of the downstream control point. Fu et al. (Fu X, Li AQ, Wang H. Allocation of flood control capacity for a multireservoir system located at the Yangtze River Basin [J]. Water Resources Management, 2014, 28(13): 4823-4834.) took the maximum reserved flood control storage capacity of the reservoir group as the goal, simulated the three-step optimization method for optimizing the optimal allocation of storage capacity, and formulated an optimal allocation strategy for the flood control storage capacity of the reservoir group in the Yangtze River Basin. In the actual scheduling process, it is necessary to take into account the flood control safety of upstream and downstream, and multi-objective optimization scheduling came into being. Yu et al. ([Yu X, Xu Y, Gu H, et al. Multi-objective robust optimization of reservoir operation for real-time flood control under forecasting uncertainty[J]. Journal of Hydrology, 2023, 620(PA): 129421.) constructed a multi-objective optimization joint optimization scheduling model for reservoir groups that takes into account the safety of upstream and downstream, so that the system flood control risk is minimized.

[0004] However, there are many objects to be protected by a reservoir group, and the flood control standards for each object are different. Usually, a reservoir group jointly protects the flood control safety of downstream farmland and towns, and also needs to protect the safety of upstream farmland, etc. Therefore, under different flood control situations, the optimization strategy of the reservoir group is different.

[0005] However, most of the existing studies are aimed at floods of a certain magnitude, and there is no systematic method to determine the optimization strategy and model determination that adapts to different flood control situations. Most studies, such as the Chinese invention patent A reservoir flood control scheduling method and system (CN 118536766 A), simulate scheduling according to the laws of hydrological events and real-time hydro-meteorological information, and the Chinese invention patent A single reservoir flood control optimization scheduling method (CN 118261286 A), adopt a fixed optimization flood control scheduling strategy, which cannot generate different flood control strategies for different flood control situations, and thus cannot more effectively utilize the reservoir's storage capacity. This patent combines the characteristics of the basin and the current state of the reservoir, and determines the reservoir group flood control optimization scheduling strategy according to different water inflow conditions and flood control needs, fully taps the storage capacity of the reservoir, and maximizes the flood control and disaster reduction role of the reservoir group. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method for joint optimization and scheduling of a group of reservoirs, which is the core model for the construction of the national flood control and scheduling system, and is a key technology that meets the needs of the new situation of flood control and disaster reduction, namely, strengthening the management of small and medium-sized floods and reducing losses caused by excessive floods. The innovation of this method lies in analyzing the flood control situation in the basin according to the real-time water conditions and working conditions of the reservoir group, determining the scheduling needs under different water inflow conditions, selecting different flood control strategies for different flood control tasks, constructing an optimization scheduling model, and then determining and formulating corresponding scheduling plans. Taking the scheduling application of the reservoir group above Laiwu in the Dawen River Basin in Shandong Province as an example, the rationality and effectiveness of the present invention have been verified.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for generating a joint flood control optimization scheduling scheme for a group of reservoirs is a joint optimization scheduling method for a group of reservoirs with different flood control situations and needs. First, according to the forecast rainfall, the size of the incoming water is forecasted, and combined with the rule scheduling simulation model, the flood control situation in the basin is judged, and the flood control scheduling objectives and needs are determined. Secondly, based on different flood control situations and needs, a corresponding joint optimization model of a group of reservoirs is constructed: for small floods within the downstream standard, the flood control demand is to reduce the downstream flood control pressure as much as possible, and the control target is to use the flood control storage capacity of the reservoir, give play to the "flood interception and peak reduction" role of the reservoir, and reduce the downstream flood peak flow as much as possible, and construct a joint optimization model of a group of reservoirs with the goal of minimizing the downstream combined flow; for floods exceeding the downstream standard, it is necessary to carry out pre-discharge scheduling of the reservoir group to reduce the downstream excessive flood volume as much as possible or even to not exceed the standard, and construct a pre-discharge optimization scheduling model for the reservoir group; for large floods, the flood control goal is to minimize the downstream flood losses while ensuring the flood control safety of the dam, and construct a multi-objective joint scheduling model of a group of reservoirs that considers the safety of the reservoir itself and the safety of the downstream protection objects. Third, the optimization model is solved using a step-by-step optimization algorithm to generate dispatching plans under different flood control situations. Finally, the flood control effects of different dispatching plans on upstream and downstream protection objects and the company itself under different flood control situations are evaluated to generate the final dispatching plan. See the attached flowchart for details. Figure 1 , which mainly includes the following steps:

[0009] Step 1: Analyze the flood control situation and determine the dispatching needs;

[0010] For reservoir groups with flood control objects downstream, based on the existing forecast and measured rainfall information, the existing hydrological model is input to obtain the forecast flood process and interval flood forecast process of each reservoir. Based on the current real-time water level of the reservoir, the regular scheduling model of each reservoir is used to simulate the outflow process of each reservoir and the forecast combined flow of the downstream section.

[0011] The flood control situation in the basin is judged according to the predicted flow of each important control section and the highest water level of the reservoir after the regulation model is dispatched, which is divided into three situations:

[0012] The first situation: small and medium floods within the downstream flood control standards;

[0013] The combined flow of each flood control section is less than or equal to the warning flow of the section, and the flood regulation high water level of each reservoir is lower than the flood control high water level. The judgment formula is shown in formula (1)-(2):

[0014] (1)

[0015] (2)

[0016] In the formula, Number the time period; is the reservoir number; j is the flood control section number, To control the number of sections, is the number of reservoirs; is the flow rate of the j flood control section, m 3 / s; is the warning flow of the j flood control section, m 3 / s, is the water level of reservoir i, m; is the flood control high water level of reservoir i, m.

[0017] The flood control requirements under this scenario are: make full use of the flood control capacity of the reservoir, give full play to the flood control, peak shifting and peak reduction functions of the reservoir, reduce the flood control pressure of the flood control section as much as possible, and reduce the impact of the flood on the downstream. That is, through the joint dispatch of the reservoir group, the flood peak flow of the downstream section can be reduced as much as possible.

[0018] The second situation: moderate floods that exceed the flood control standards of downstream or upstream protection objects;

[0019] When the maximum flow of at least one section of each flood control section exceeds the warning flow, or the flood regulation high water level of any reservoir is higher than the flood control high water level, the judgment formula is shown in formulas (3)-(4):

[0020] (3)

[0021] (4)

[0022] In the formula, Number the time period; is the reservoir number; j is the flood control section number, To control the number of sections, is the number of reservoirs; is the flow rate of the j flood control section, m 3 / s; is the warning flow of the j flood control section, m 3 / s, is the water level of reservoir i, m; is the flood control high water level of reservoir i, m.

[0023] The flood control needs in this scenario are: it is necessary to use forecast information, and the reservoir should adopt a pre-discharge scheduling method to control the peak flow in the downstream section not to exceed the safe discharge volume and the maximum water level of the reservoir not to exceed the flood control high water level or the Yongshui water level.

[0024] The third situation: a major flood that exceeds the flood control standards of downstream or upstream protected areas;

[0025] After the reservoir was pre-discharged according to the maximum pre-discharge volume, the maximum flow in the flood control section still exceeded the warning flow.

[0026] In this scenario, the flood control situation is more severe. The reservoir cannot guarantee the flood control safety of upstream and downstream protection objects through pre-discharge scheduling. The upstream and downstream will inevitably exceed the standard. At this time, it is necessary to weigh the upstream and downstream flood control goals and determine the scheduling plan that satisfies the decision makers. The flood control demand is: while the reservoir adopts the pre-discharge scheduling method, take the upstream and downstream flood control safety as the optimization goal, and formulate a satisfactory scheduling plan that weighs the upstream and downstream flood control.

[0027] Step 2: Determine the optimal strategy for reservoir groups under different flood control situations and build an optimal dispatching model;

[0028] According to the different magnitudes of floods and corresponding flood control needs determined in step one, the optimization strategy is determined and the corresponding optimization scheduling model is constructed.

[0029] Step 2.1, for small and medium-sized floods within the flood control standards: construct a reservoir group joint optimization scheduling model with the reservoir itself and the reservoir group as the target.

[0030] The optimization strategy in this scenario is to minimize the sum of squares of the combined flow of each reservoir flood control section and the downstream common protection flood control section as the optimization target. In order to make the peak flow as low as possible, the optimization target is to minimize the sum of squares of the combined flow of the reservoir flood control section and the downstream common protection flood control section as the optimization target, as shown in formula (5). The section flow is composed of the flow from the reservoir discharge to the control section and the flow between the control sections, as shown in formula (6).

[0031] f 1 = min ∑ t = 1 T ∑ i = 1 N [ Q n ( t ) ] 2 (5)

[0032] (6)

[0033] In the formula, t is the time period number; Indicates the total number of time periods; is the reservoir number, N represents the total number of reservoirs; j is the control section interval number; n is the control section number; Control section n Time flow, , is the discharge from reservoir i to the downstream control section, is the flow rate of the control section interval j; It represents the objective function of the reservoir group joint optimization dispatching model with the reservoir itself and the reservoir group as the target; Expressed as the flow rate of control section n.

[0034] Step 2.2, for medium floods exceeding the downstream flood control standards: construct a reservoir group pre-discharge optimization scheduling model.

[0035] Step 2.2.1, the flood dispatch model at this level includes two dispatch modules, one is the pre-discharge module, and the other is the flood control module.

[0036] The flood control module is consistent with the reservoir group joint optimization model in step 2.1.

[0037] The principles of the pre-discharge module are as follows:

[0038] Determine the pre-discharge scheduling reservoirs: first, select the reservoirs whose flood control high water level exceeds the flood control high water level or whose downstream flow exceeds the warning flow; secondly, the forecast accuracy must be high, requiring it to reach Class B or above; the pre-discharge time needs to be longer than the evolution time from the reservoir to the downstream flood control section.

[0039] Determine the pre-release time: based on the forecast period of the forecast information used, and deduct the time for operation, operation and decision-making;

[0040] Determine the boundary conditions for pre-discharge: the lowest water level for pre-discharge of each reservoir is the dead water level; the pre-discharge flow value cannot exceed the safe flow corresponding to the downstream flood control standard, and must be within the discharge capacity.

[0041] On the basis of meeting the above principles, the pre-discharge volume is determined according to the current water level of the reservoir and the predicted water inflow, and a graded pre-discharge method is adopted, such as the following graded discharge method:

[0042] (7)

[0043] In the formula, For the reservoir Pre-discharge section discharge flow, ; For the reservoir exist The maximum discharge flow when the gate is fully open during the period, ; To forecast flood volume, ; The first level standard for flood control of the reservoir corresponds to the flood volume, 10,000 ; The second level flood control standard of the reservoir corresponds to the flood volume, 10,000 .

[0044] Step 2.2.2, determine the water inflow conditions that can be used to adjust floods that exceed the downstream flood control standards to the point where the flow at the downstream flood control section does not exceed the warning level through pre-discharge scheduling: using floods of various magnitudes as input, calculate the downstream combined flow and reservoir flood control high water level when pre-discharge scheduling is performed with different water levels as the starting water level, and determine the water inflow and reservoir water level conditions that do not exceed the standards both upstream and downstream.

[0045] Step 2.2.3, optimization scheduling model: The optimization strategy in this scenario is to minimize the combined flow of the reservoir group itself and the common protection flood control section after the reservoir pre-discharge simulation, in order to make the peak flow as low as possible. The objective function is the same as in step 2.1.

[0046] Step 2.3: Floods where upstream and downstream flood control safety cannot be guaranteed by pre-discharge scheduling: Construct a multi-objective joint optimization scheduling model for reservoir groups; the details are as follows:

[0047] For floods where the upstream and downstream flood control safety cannot be guaranteed by pre-discharge scheduling, the optimization strategy is: it is necessary to take into account the upstream and downstream flood control safety. Construct a multi-objective optimization scheduling model, quantify the competitive relationship between the upstream and downstream flood control objectives of the reservoir group, formulate a reservoir group storage capacity allocation strategy, achieve efficient and reasonable allocation of the reservoir group storage capacity, and improve the overall flood control capacity of the basin reservoir group. The multi-objective joint optimization scheduling model of the reservoir group takes the minimum occupancy rate of the maximum flood control storage capacity of the reservoir group system and the minimum flow of the downstream control section as flood control objectives. The objective function of the minimum downstream combined flow is consistent with that in step 2.1, and the objective function of the minimum occupancy rate of the maximum flood control storage capacity of the reservoir group system is shown in formulas (8)-(9).

[0048] (8)

[0049] (9)

[0050] In the formula, For the reservoir The maximum occupancy rate of flood control reservoir capacity is squared; is the sum of the squares of the flood control capacity occupancy rate of the reservoir group system; Indicates the number of reservoirs; For the reservoir exist The storage capacity used at any time is ; For the reservoir The reservoir capacity corresponding to the flood limit water level, ; is the reservoir capacity corresponding to the flood level once in 50 years, .

[0051] Step 3, generating dispatching plans under different flood control situations;

[0052] The optimization scheduling model is constructed based on the goal determined in step 2. Each model must meet the following constraints:

[0053] a. Water balance constraints;

[0054] (10)

[0055] In the formula, , For the reservoir No. , Reservoir water storage capacity during the period, 10,000 ; For the reservoir No. Reservoir inflow during the period, ; For the reservoir No. Reservoir outflow during the period, ; To calculate the length of the period, .

[0056] b. Water level constraints;

[0057] The joint optimization scheduling model allows the lowest water level to be the flood limit water level. When facing a large flood or a flood exceeding the flood control standard, the lowest allowable water level is set to the dead water level. When facing a flood within the downstream flood control standard or a flood exceeding the flood control standard, the highest allowable water level is set to the flood control high water level. When facing a flood that cannot ensure the upstream and downstream flood control safety through pre-discharge scheduling, the highest allowable water level can be a water level corresponding to a higher flood control standard.

[0058] (11)

[0059] In the formula, , Reservoirs The upper and lower limits of the water level, ; For the reservoir No. Reservoir water level during the period, .

[0060] c. Reservoir discharge capacity constraints;

[0061] The discharge flow from the reservoir shall not exceed the maximum discharge flow when the gate is fully opened.

[0062] (12)

[0063] In the formula, For the reservoir exist The maximum discharge flow rate during the period, .

[0064] d. Reservoir discharge constraints;

[0065] In order to ensure the flood control safety downstream of the reservoir itself, the discharge flow shall not exceed the downstream safe discharge.

[0066] (13)

[0067] In the formula, For the reservoir exist The discharge flow rate during the period, ; For the reservoir The downstream safety discharge flow rate is .

[0068] e. Reservoir final water level constraint;

[0069] In order to better regulate the next flood and ensure the flood control safety of the reservoir, the water level should return to the flood limit level as soon as possible after the flood ends.

[0070] (14)

[0071] In the formula, For the reservoir Water level at the end of the period, ; For the reservoir The flood limit water level.

[0072] f. Reservoir discharge does not exceed the reservoir inflow constraints;

[0073] To ensure downstream safety and avoid artificial flood peaks, the reservoir outflow shall not exceed the inflow peak flow.

[0074] (15)

[0075] In the formula, For the reservoir The peak inflow flow is .

[0076] g. Reservoir discharge amplitude constraints;

[0077] To avoid frequent adjustments to the gate opening, the fluctuation range of reservoir outflow in adjacent time periods should not be too large.

[0078] (16)

[0079] In the formula, For the reservoir The fluctuation range of outbound flow in adjacent periods, .

[0080] For the scenarios of step 2.1 and step 2.2, the optimization model is solved using a stepwise optimization algorithm to obtain the optimal outflow process and water level process of different magnitudes of incoming water. Scenario step 2.3 is a multi-objective optimization problem. This patent converts the multi-objective into a single objective by weighted summation, and then still uses a stepwise optimization algorithm to solve it. The weight is determined by the decision maker's preference.

[0081] Step 4, evaluate the effect of the joint optimization operation model of the reservoir group considering the hierarchical flood control objectives;

[0082] The optimal process of joint dispatching of the reservoir group calculated in step 3 is compared with the regular dispatching process in step 1. The optimization effect of the model is evaluated by indicators such as the maximum flood control water level of each reservoir, the maximum peak reduction rate of the reservoir, the maximum total flood control capacity of the reservoir group, the peak flow and peak time of the downstream common flood control section.

[0083] Among them, the maximum peak reduction rate of the reservoir is shown in formula (17).

[0084] (17)

[0085] In the formula, For the reservoir Maximum peak clipping rate, % For the reservoir The maximum discharge flow during flood control, ; For the reservoir The peak flow rate into the reservoir during flood control, When constructing a multi-objective joint optimization scheduling model for a reservoir group, a series of scheduling schemes are generated by setting different target weights. The optimization effect of the model is evaluated to compare and select multi-objective schemes by comparing indicators such as the flood control storage capacity used in each scheduling scheme and the peak flow of the common protection section downstream of the reservoir.

[0086] Based on the evaluation results of the above indicators, decision makers can modify the pre-discharge volume, the reservoirs involved in pre-discharge scheduling, and the reservoirs involved in optimized scheduling through human-computer interaction to determine the final scheduling plan.

[0087] Compared with the prior art, the present invention has the following advantages and effects:

[0088] The present invention provides a method for generating a joint flood control optimization scheduling plan for a group of reservoirs. Based on the analysis of the flood control situation, the flood control needs under different water inflow scenarios and reservoir water storage conditions are determined, thereby determining the optimization strategy for the optimized scheduling, constructing a corresponding optimized scheduling model, and generating a scheduling plan that meets the flood control needs. The method is suitable for flood control scheduling of reservoir groups in various river basins and can adapt to the current new flood control form requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 It is a flow chart of a joint optimization dispatching method for a group of reservoirs considering graded flood control objectives.

[0090] Figure 2 This is the flow process diagram of the Qiaodian Reservoir's five-year design flood dispatching.

[0091] Figure 3This is the water level process diagram of the Qiaodian Reservoir's five-year design flood regulation.

[0092] Figure 4 This is the flow process diagram of the Qiaodian Reservoir's design flood dispatching for a return period of once in 25 years.

[0093] Figure 5 This is the 25-year designed joint dispatching water level process diagram of Qiaodian Reservoir. DETAILED DESCRIPTION

[0094] The present invention is further described below in conjunction with specific embodiments.

[0095] The present invention takes the Dawen River basin above Laiwu as an example, divides it into three flood magnitude situations, and describes the specific implementation method in detail in combination with the technical scheme and the attached drawings. Among them, the basin above Laiwu contains four reservoirs, namely Hulushan Reservoir, Qiaodian Reservoir, Yangjiaheng Reservoir, and Gouli Reservoir. The flood control standard of the downstream river of each reservoir is once in 20 years. The four reservoirs jointly protect the Laiwu section, and its river flood control standard is once in 20 years, corresponding to a safe flow of 2200m 3 / s.

[0096] The implementation method specifically includes the following steps:

[0097] Step 1: Analyze the flood control situation and determine the dispatching needs;

[0098] When a five-year design flood occurs in the basin, the five-year design flood process is input into the reservoir group regular dispatching model for regulation calculation. The results show that the flood regulation high water level of each reservoir does not exceed the flood control high water level. The peak flow of Laiwu section is 1495 m 3 / s, does not exceed the safety flow rate of 2200 m 3 / s, the comprehensive assessment is: a small flood within the flood control standard has occurred. The flood control demand is: the joint dispatch of the reservoir group to reduce the peak flow of the Laiwu section as much as possible.

[0099] When a 25-year design flood occurred in the basin, the high water levels of the flood regulation after the regular operation of each reservoir did not exceed the high water level for flood control. The peak flow of the Wu section downstream of the reservoir was 2559 m 3 / s, exceeding the safety flow rate by 2200 m 3 / s, the comprehensive assessment is: a medium flood exceeding the downstream flood control standard has occurred. The flood control needs are: pre-discharge scheduling and joint scheduling of the reservoir group to keep the flood peak flow at the Laiwu section below the safety value as much as possible.

[0100] When a 30-year design flood occurs in the basin, the high water levels of flood regulation after regular operation of each reservoir exceed the high water level for flood control. The peak flow rate of Laiwu section downstream of the reservoir is 2800 m 3 / s, exceeding the safety flow rate by 2200 m 3 / s, and the comprehensive assessment is: a major flood that exceeds the downstream flood control standard. The flood control needs are: reservoir group pre-discharge scheduling and joint scheduling, and joint multi-objective flood control optimization scheduling considering upstream and downstream flood control safety.

[0101] Step 2: Determine the optimization strategy for the reservoir group and build an optimization scheduling model;

[0102] Design flood with a return period of 5 years: Construct a joint optimization scheduling model for a group of reservoirs with the goal of minimizing the sum of squared combined flows of the downstream sections of Hulushan Reservoir, Qiaodian Reservoir, Yangjiaheng Reservoir, Gouli Reservoir and the Laiwu section they jointly protect.

[0103] 25-year design flood: The reservoir pre-discharge is determined according to the formula in formula (7) when the predicted flood volume is between the first and second level standards of reservoir flood control. The upper limits of the pre-discharge for Hulushan Reservoir, Qiaodian Reservoir, Yangjiaheng Reservoir, and Gouli Reservoir are 250 m 3 / s, 120 m 3 / s,40 m 3 / s,91 m 3 / s. The optimized model is consistent with the 5-year return period.

[0104] Design flood once in 30 years: the pre-discharge volume is the same as the previous case, and the optimization target is to increase the optimization target of mobilizing the maximum flood control capacity of four reservoirs with the minimum capacity.

[0105] Step 3, generating a dispatching plan under the current flood control situation;

[0106] The optimization scheduling model is constructed with the objectives determined in the above steps. Among the model constraints, the optimization model allows the lowest water level to be the flood limit water level of the reservoir, and the highest water level to be the high water level of the reservoir for flood control. The optimization model is solved using a stepwise optimization algorithm to obtain the optimal outflow process and water level process under the current water inflow conditions, and generate a scheduling plan.

[0107] Step 4, evaluate the effect of the joint optimization operation model of the reservoir group considering the hierarchical flood control objectives;

[0108] Design flood once in 5 years: Figure 2 , Figure 3 As shown in Table 1, the joint optimization dispatching takes into account the flood control section of the reservoir itself and the reservoir group at the same time, and combines the interval water inflow process. In the corresponding period of high flow in the downstream section, each reservoir fully utilizes the flood control storage capacity to intercept and store flood water and reduce outflow to stagger the downstream flow while ensuring its own flood control safety. Taking the maximum peak reduction rate as the evaluation index, the peak reduction effect of each reservoir has been significantly improved, and the peak flow reduction effect on the downstream Laiwu section is obvious, from 1495 m / s in the regular dispatching to 1020 m / s. 3 / s.

[0109] Table 1, results of rule-based dispatch and joint optimization dispatch for the 5-year design flood;

[0110]

[0111] 25-year design flood: Figure 4 , Figure 5 From Table 2, we can see that the effective pre-discharge time of the four reservoirs in the basin is 14 hours, and all of them participate in pre-discharge scheduling. The pre-discharge magnitude is determined according to formula (7), and the results are shown in the following table. It can be seen that when a flood occurs once in 25 years, if the flood limit water level is used as the starting water level, and the 14-hour flood forecast information is used for pre-discharge optimization scheduling, the combined pre-discharge optimization scheme can reduce the peak flow of the Laiwu section from the regular 2559m 3 / s adjusted to 2158m 3 / s. Through the optimized scheduling of reservoir group pre-discharge, the 25-year flood can be regulated to the corresponding flow of the flood control standard of the common protection objects downstream, avoiding the overflow of river sections and the inundation of farmland and villages.

[0112] Table 2, results of regular operation and joint pre-discharge optimization operation for the design flood with a return period of 25 years;

[0113]

[0114] 30-year design flood: Table 3 shows the multi-objective flood control optimization scheduling results of the reservoir group under different weight schemes for the 30-year design flood:

[0115] Scheme 1 takes the flood control storage capacity utilization rate of the reservoir group as small as possible as the flood control goal: the optimized dispatching scheme uses the flood control storage capacity of 19.0389 million m 3 , 1.0533 million m more than the regular plan 3 The flood control reservoir capacity reduces the peak flow of the downstream Laiwu section from the regular 2800m 3 / s reduced to 2354m 3 / s, reducing the flood control pressure downstream, but still exceeding the 20-year flood control standard for the downstream common flood control objects, corresponding to a guaranteed flow of 2200m 3 / s.

[0116] Scheme 2 considers both upstream and downstream flood control targets, but focuses on the flood control safety of upstream reservoirs, setting the upstream flood control target weight coefficient to 0.7. The joint optimization scheduling scheme uses a flood control reservoir capacity of 19.7065 million m 3 , 2.1328 million m more than the regular plan 3 The flood control reservoir capacity reduces the peak flow of the downstream Laiwu section from the regular 2800m 3 / s reduced to 2269m 3 / s, which can further reduce the flow in the downstream section compared with Plan 1, but it still exceeds the flood control standard of once in 20 years.

[0117] Scheme 3 sets the weight coefficient of upstream and downstream flood control targets to 0.5. Joint optimization dispatching uses 20.6051 million m3 of flood control reservoir capacity 3 , 2.1328 million m more than the regular plan 3 The flood control capacity can ensure that the downstream section of the reservoir and the common flood control section do not exceed the flow corresponding to the flood control standard of once in 20 years, and the Laiwu section is reduced to 2145m 3 / s.

[0118] Scheme 4: Joint optimization dispatch focuses on downstream flood control safety, setting the downstream flood control target weight to 0.7. The total flood control storage capacity of the upstream reservoir group is 21.4032 million m 3 , 3.4176 million m more than the regular plan 3 The flood control reservoir capacity can further reduce the peak flow of the downstream Laiwu section to 2061m 3 / s. The downstream flood control target has a larger weight, which can give full play to the reservoir's regulation and storage function and reduce Laiwu's flood control pressure to a certain extent.

[0119] Scheme 5 shows that the flood control target is to minimize the flow of the downstream flood control section. When the water level does not exceed the design flood level of once in 50 years, the upstream reservoir will make full use of its storage capacity to intercept and store flood water, so that the peak flow of the downstream Laiwu section is minimized. The total flood control storage capacity of the upstream reservoir group is 21.9999 million m 3 , 4.0143 million m more than the regular plan 3 The flood control reservoir can reduce the peak flow of the downstream Laiwu section to 1993m3, which is a once-in-15-year event. 3 / s, minimizing the flood control pressure in downstream Laiwu, but the flood control risk of the upstream reservoir group is relatively high.

[0120] Table 3. Results of multi-objective flood control optimization scheduling of reservoir groups under different weight schemes

[0121]

[0122] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for generating a joint flood control optimization scheduling plan for a reservoir group, characterized in that: The steps of the method for generating a joint flood control optimization scheduling scheme for a group of reservoirs are as follows: first, based on the forecast rainfall, the water inflow is forecasted, and combined with the rule scheduling simulation model, the flood control situation in the basin is judged, and the flood control scheduling objectives and needs are determined; second, based on different flood control situations and needs, a corresponding joint optimization model for a group of reservoirs is constructed: for small floods within the downstream standard, a joint optimization model for a group of reservoirs with the goal of minimizing the downstream combined flow is constructed; for floods exceeding the downstream standard, a reservoir group pre-discharge optimization scheduling model is constructed; for large floods, a multi-objective joint scheduling model for a group of reservoirs is constructed that takes into account the safety of the reservoir itself and the safety of the downstream protection objects; third, the model constructed in the previous step is solved to generate scheduling schemes under different flood control situations, which specifically includes the following steps: Step 1: Analyze the flood control situation and determine the dispatching needs; For the reservoir groups with flood control objects downstream, the forecast flood process and interval flood forecast process of each reservoir are obtained. Based on the current real-time water level of the reservoir, the regular dispatching model of each reservoir is used to simulate the outflow process of each reservoir and the forecast combined flow of the downstream section; The flood control situation in the basin is judged according to the predicted flow of each important control section and the highest water level of the reservoir after the regulation of the regular regulation model, which is divided into three situations: The first situation: small and medium floods within the downstream flood control standards; The combined flow of each flood control section is less than or equal to the warning flow of the section, and the flood regulation high water level of each reservoir is lower than the flood control high water level. The judgment formula is shown in formula (1)-(2): Where t is the time period number; i is the reservoir number; j is the flood control section number; m is the number of control sections; n is the number of reservoirs; Q sec_j,t is the flow rate of the j flood control section, m 3 / s;Q warn_j,s is the warning flow of the j flood control section, m 3 / s,Z res_i,t is the water level of reservoir i, m; Z high_i is the flood control high water level of reservoir i, m; The flood control requirements in this scenario are: reducing the peak flow in the downstream section through joint operation of the reservoir group; The second situation: moderate floods that exceed the flood control standards of downstream or upstream protection objects; When the maximum flow of at least one section of each flood control section exceeds the warning flow, or the flood regulation high water level of any reservoir is higher than the flood control high water level, the judgment formula is as shown in formula (3)-(4): Where t is the time period number; i is the reservoir number; j is the flood control section number; m is the number of control sections; n is the number of reservoirs; Q sec_j,t is the flow rate of the j flood control section, m 3 / s;Q warn_j,s is the warning flow of the j flood control section, m 3 / s,Z res_i,t is the water level of reservoir i, m; Z high_i is the flood control high water level of reservoir i, m; The flood control requirements under this scenario are: using forecast information, the reservoir adopts pre-discharge scheduling to control the flood peak flow at the downstream section not to exceed the safe discharge volume and the maximum water level of the reservoir not to exceed the flood control high water level or the Yongshui water level; The third situation: a major flood that exceeds the flood control standards of downstream or upstream protected areas; After the reservoir is pre-discharged according to the maximum pre-discharge volume, the maximum flow of the flood control section still exceeds the warning flow; The flood control requirements in this scenario are: while the reservoir adopts the pre-discharge scheduling method, the upstream and downstream flood control safety is optimized, and a scheduling plan that balances upstream and downstream flood control is formulated; Step 2: Determine the optimal strategy for reservoir groups under different flood control situations and build an optimal dispatching model; According to the different magnitudes of floods and corresponding flood control needs determined in step 1, determine the optimization strategy and build a corresponding optimization scheduling model; Step 2.1, for small and medium floods within the flood control standard: construct a reservoir group joint optimization dispatching model with the reservoir itself and the reservoir group as the target; the optimization target is to minimize the sum of squares of the combined flow of the reservoir flood control section and the downstream joint protection flood control section, as shown in formula (5); the section flow is composed of the flow from the reservoir discharge to the control section and the flow between the control sections, as shown in formula (6); Where t is the time period number, T is the total number of time periods; i is the reservoir number, N is the total number of reservoirs; j is the control section interval number; n is the control section number; Q n (t) is the flow rate of the control section n in the tth period, m 3 / s, is the discharge from reservoir i to the downstream control section, Q sec_j is the flow rate of section j; f1 represents the objective function of the reservoir group joint optimization dispatching model with the reservoir itself and the reservoir group as the target; Q n It is expressed as the flow rate of control section n; Step 2.2, for medium floods exceeding the downstream flood control standard: construct a reservoir group pre-discharge optimization scheduling model; Step 2.2.1, the flood dispatch model under this magnitude includes two dispatch modules, one is the pre-discharge module, and the other is the flood control module; The flood control module is consistent with the reservoir group joint optimization model in step 2.1; On the basis of meeting the pre-discharge module principle, the pre-discharge amount is determined according to the current water level of the reservoir and the predicted water inflow, and a graded pre-discharge method is adopted as follows: In the formula, Q pre_i is the discharge flow of the pre-discharge section of reservoir i, m 3 / s; is the maximum discharge flow of reservoir i when the gate is fully open at time t, m 3 / s; W is the predicted flood volume, ten thousand m 3 ; W1 is the first level standard corresponding to the flood volume of the reservoir, 10,000 m 3 ; W2 is the flood volume corresponding to the second level flood control standard of the reservoir, 10,000 m 3 ;Q i,s is the downstream safe discharge of reservoir i, m 3 / s; Step 2.2.2, determine the water inflow conditions that can be used to adjust the flood that exceeds the downstream flood control standard to the downstream flood control section flow that does not exceed the warning level through pre-discharge scheduling: using floods of various magnitudes as input, calculate the downstream combined flow and reservoir flood control high water level when pre-discharge scheduling is performed with different water levels as the starting water level, and determine the water inflow and reservoir water level conditions that do not exceed the standard both upstream and downstream; Step 2.2.3, optimization dispatch model: The optimization strategy in this scenario is to minimize the combined flow of the reservoir group itself and the common protection flood control section after the reservoir pre-discharge simulation. In order to make the peak flow as low as possible, the objective function is the same as in step 2.1; Step 2.3: Floods where upstream and downstream flood control safety cannot be guaranteed by pre-discharge scheduling: Construct a multi-objective joint optimization scheduling model for reservoir groups; the details are as follows: The optimization strategy is: it is necessary to take into account the flood control safety of upstream and downstream, and to build a multi-objective optimization scheduling model for the reservoir group. The model takes the minimum occupancy rate of the maximum flood control storage capacity of the reservoir group system and the minimum flow rate of the downstream control section as flood control objectives. The objective function of minimizing the downstream combined flow rate is consistent with that in step 2.1, and the objective function of minimizing the maximum flood control storage capacity occupancy rate of the reservoir group system is shown in formulas (8)-(9). In the formula, A i is the square of the maximum occupancy rate of flood control storage capacity of reservoir i; A is the sum of the squares of the occupancy rates of flood control storage capacity of the reservoir group system; n represents the number of reservoirs; V i,t is the storage capacity of reservoir i at time t, 10,000 m 3 ; V i,min is the storage capacity corresponding to the flood limit water level of reservoir i, 10,000 m 3 ; V i,high is the reservoir capacity corresponding to the flood level once in 50 years, 10,000 m 3 ; Step 3, generating dispatching plans under different flood control situations; Construct an optimization scheduling model based on the goal determined in step 2. Each model must meet the constraints; For the scenarios of step 2.1 and step 2.2, the stepwise optimization algorithm is used to solve each model to obtain the optimal outflow process and water level process of different magnitudes of incoming water; scenario step 2.3 is a multi-objective optimization problem. The multi-objective is converted into a single objective through weighted summation, and then the stepwise optimization algorithm is still used to solve it.

2. A method for generating a joint flood control optimization scheduling plan for a reservoir group according to claim 1, characterized in that: The method for generating a joint flood control optimization scheduling scheme for a group of reservoirs also includes step 4, evaluating the effect of the joint optimization scheduling model for a group of reservoirs considering the hierarchical flood control objectives; specifically, The optimal process of joint dispatching of the reservoir group calculated in step 3 is compared with the regular dispatching process in step 1. The optimization effect of the model is evaluated by the highest flood control water level of each reservoir, the maximum peak reduction rate of the reservoir, the maximum total flood control storage capacity of the reservoir group, the peak flow and peak time of the downstream common flood control section; Among them, the maximum peak reduction rate of the reservoir is shown in formula (17); In the formula, ω i is the maximum peak reduction rate of reservoir i, %; Q out_i,max is the maximum discharge flow during flood control of reservoir i, m 3 / s;Q in_i,max is the peak inflow flow during flood control of reservoir i, m 3 / s; When constructing a multi-objective joint optimization dispatching model for a reservoir group, a series of dispatching schemes are generated by setting different objective weights, evaluating the optimization effect of the model, and comparing and selecting multi-objective schemes; Based on the evaluation results of the above indicators, decision makers modify the pre-discharge volume, reservoirs participating in pre-discharge scheduling, and reservoirs participating in optimized scheduling through human-computer interaction to determine the final scheduling plan.

3. The method for generating a joint flood control optimization scheduling plan for a reservoir group according to claim 1 is characterized in that: In step 2.2.1, the pre-discharge module principle is as follows: Determine the pre-discharge scheduling reservoir: First, select the reservoirs whose flood control high water level exceeds the flood control high water level or whose downstream exceeds the warning flow; secondly, the forecast accuracy is required to reach Class B or above; the pre-discharge time needs to be longer than the evolution time from the reservoir to the downstream flood control section; Determine the pre-release time: based on the forecast period of the forecast information used, and deduct the time for operation, operation and decision-making; Determine the boundary conditions for pre-discharge: the lowest water level for pre-discharge of each reservoir is the dead water level; the pre-discharge flow value cannot exceed the safe flow corresponding to the downstream flood control standard, and must be within the discharge capacity.

4. The method for generating a joint flood control optimization scheduling plan for a reservoir group according to claim 1, characterized in that: The constraints in step 3 are as follows: a. Water balance constraints; V i,t+1 =V i,t +(Q in_i,t -Q out_i,t )×Δt(10) Where V i,t 、V i,t+1 is the water storage capacity of reservoir i at the time period t and t+1, 10,000 m 3 ;Q in_i,t is the inflow of reservoir i in period t, m 3 / s;Q out_i,t is the outflow of reservoir i in period t, m 3 / s; Δt is the length of the calculation period, h; b. Water level constraints; The joint optimization scheduling model allows the lowest water level to be the flood limit water level. When facing a large flood or a flood exceeding the flood control standard, the lowest allowable water level is set to the dead water level. When facing a flood within the downstream flood control standard or a flood exceeding the flood control standard, the highest allowable water level is set to the flood control high water level. When facing a flood that cannot ensure the upstream and downstream flood control safety through pre-discharge scheduling, the highest allowable water level can be a water level corresponding to a higher flood control standard. i,down ≤H i,t ≤H i,up (11) In the formula, H i,up , H i,down are the upper and lower limits of the water level of reservoir i, m; H i,t is the water level of reservoir i in period t, m; c. Reservoir discharge capacity constraints; The discharge flow from the reservoir shall not exceed the maximum discharge flow when the gate is fully opened; In the formula, is the maximum discharge flow of reservoir i in period t, m 3 / s; d. Reservoir discharge constraints; To ensure the flood control safety of the reservoir's downstream, the discharge flow should not exceed the downstream safe discharge flow; Q out_i,t ≤Q i,s (13) In the formula, Q out_i,t is the discharge flow of reservoir i in period t, m 3 / s;Q i,s is the downstream safe discharge of reservoir i, m 3 / s; e. Reservoir final water level constraint; In order to better regulate the next flood and ensure the flood control safety of the reservoir, the water level should return to the flood limit level as soon as possible after the flood ends; H i,T =H i,min (14) In the formula, H i,T is the water level of the reservoir at the end of period i, m; H i,min is the flood limit water level of reservoir i; f. Reservoir discharge does not exceed the reservoir inflow constraints; To ensure downstream safety and avoid artificial flood peaks, the outflow from the reservoir should not exceed the inflow peak flow; 0≤Q out_i,t ≤Q in_i,max (15) In the formula, Q in_i,max is the peak inflow flow of reservoir i, m 3 / s; g. Reservoir discharge amplitude constraints; To avoid frequent adjustment of gate opening, the fluctuation range of reservoir outflow in adjacent periods should not be too large; |Q out_i,t+1 -Q out_i,t |≤ΔQ i (16) Where ΔQ i is the fluctuation range of outflow from reservoir i in adjacent periods, m 3 / s;Q out_i,t+1 It represents the outflow of reservoir i in the t+1th period.

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