A method and device for generating an optimal scheduling scheme for a stepped reservoir during a drawdown period

Abstract

The application provides a kind of generation method and device of cascade reservoir drawdown period optimization scheduling scheme, which comprises the following steps: collecting cascade reservoir engineering characteristic basic data and long series natural runoff data; using time series analysis method to generalize the maximum discharge constraint of cascade reservoir drawdown period under the influence of various factors; constructing a cascade reservoir drawdown period optimization scheduling model, determining the water abandonment quantity penalty factor in different typical years; solving the cascade reservoir drawdown period optimization scheduling model to obtain the optimal water level process line of cascade reservoir; judging the size relationship between the relative water abandonment quantity of cascade reservoir drawdown period and the preset threshold value year by year, and adjusting the water abandonment quantity penalty factor as appropriate; arranging the reservoir water level and overall water to be consumed of each cascade reservoir at different control time nodes in different typical years to form the drawdown period optimization scheduling scheme. The application has the advantages of being simple and practical, reasonable and reliable, easy to popularize, etc., and can provide decision support for real-time scheduling of cascade reservoir operation and management departments.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy and hydropower, and particularly relates to a method and device for generating a cascade reservoir drawdown period optimal scheduling scheme. BACKGROUND

[0002] The drawdown period has the characteristics of long time duration and wide range of comprehensive utilization tasks and scheduling requirements. Cascade reservoir power stations usually take the maximum power generation and the minimum water abandonment as the drawdown period scheduling objectives. Therefore, the reservoir water level is generally kept at a high level before the drawdown period to improve the water resource utilization efficiency of the power station; and the reservoir water level is lowered to the specified operating range in the flood period. Due to the long time span of the drawdown period, the power generation flow of the cascade reservoir power station is restricted by multiple factors such as water power station maintenance, line maintenance, power grid peak regulation, water supply scheduling, and ecological scheduling. Once the forecast inflow is large in the later period, the cascade reservoir will have to lower the reservoir water level to the specified operating range in the form of gate opening and water abandonment. At the same time, due to the similar hydrological rhythm and close hydraulic connection of the cascade reservoirs, the drawdown process of the upstream cascade reservoir directly affects the water inflow level of the downstream cascade reservoir, and the high water level operation of the downstream cascade reservoir may affect the tail water level of the upstream cascade reservoir, thereby affecting the power generation head of the upstream power station.

[0003] At present, the optimal scheduling mode of the cascade reservoir drawdown period usually takes the maximum power generation or the minimum water abandonment as the target for optimization, and fails to effectively coordinate the relationship between the two. In the optimization process, the influence of factors such as water power station maintenance, line maintenance, power grid peak regulation, water supply scheduling, and ecological scheduling on the maximum power output and power generation flow of the power station is not effectively considered, resulting in weak guidance of the optimized results to actual scheduling. In addition, due to the high dimension of the decision variable of the optimization target of the cascade reservoir, the dimension of the decision variable in each period is directly determined by the cascade number of the cascade hydropower stations, which leads to the problem of "dimension disaster" as a key factor restricting the practicability of the optimization algorithm. SUMMARY

[0004] The present application aims to provide a method and device for generating a cascade reservoir drawdown period optimal scheduling scheme, which can effectively coordinate the relationship between the power generation and water abandonment, consider the influencing factors, and solve the problem of "dimension disaster", thereby providing technical support for guiding the drawdown period scheduling operation decision of the cascade reservoir.

[0005] In order to achieve the above-mentioned purpose, in a first aspect, the present application provides a method for generating a cascade reservoir drawdown period optimal scheduling scheme, comprising:

[0006] Step 1, collecting the engineering characteristic basic data and long series natural runoff data of the cascade reservoir;

[0007] Step 2, based on the engineering characteristic basic data and long series natural runoff data, the time series analysis method is used to generalize the maximum discharge constraint of the cascade reservoir under various influence factors in the drawdown period;

[0008] Step 3, the cascade reservoir drawdown period optimization scheduling model considering the maximum power generation and the minimum water abandonment is constructed, the drawdown period inflow frequency analysis is carried out, and the water abandonment penalty factor in different typical years is determined;

[0009] Step 4, the step-by-step optimization algorithm and the successive approximation algorithm are combined to solve the cascade reservoir drawdown period optimization scheduling model, and the optimal water level process line of the cascade reservoir is obtained;

[0010] Step 5, according to the optimal water level process line and the water abandonment penalty factor in different typical years, the relative water abandonment in the drawdown period of the cascade reservoir is counted in each typical year, and according to the size relationship between the relative water abandonment and the preset threshold value, the water abandonment penalty factor or the water abandonment and the water to be consumed in each period of the cascade reservoir is counted;

[0011] Step 6, according to the scheduling operation needs, different control time nodes of each cascade reservoir in different typical years are determined, the reservoir water level and the overall water to be consumed at each control time node are counted, and the drawdown period optimization scheduling scheme is formed.

[0012] According to the generation method of the cascade reservoir drawdown period optimization scheduling scheme provided by the application, the engineering characteristic basic data includes the normal water level of each cascade reservoir, the water level-storage capacity curve, the start and end time of the drawdown period, the full-load discharge, the minimum discharge, the reservoir water level amplitude constraint, the tail water level relationship curve and the operation water level at the end of the drawdown period; and the various influence factors include the power station maintenance, the line maintenance, the power grid peak regulation, the water supply scheduling and the ecological scheduling.

[0013] According to the generation method of the cascade reservoir drawdown period optimization scheduling scheme provided by the application, step 2 specifically includes:

[0014] Based on the time scale of long series natural runoff data, the time step of the drawdown period of the cascade reservoir is determined;

[0015] According to the start and end time of the drawdown period and the time step, the drawdown period is divided into n periods, wherein n = TS / dt, TS = T1-T0; in the formula, T0 is the start time of the drawdown period, T1 is the end time of the drawdown period, TS is the duration of the drawdown period, and dt is the time step of the drawdown period;

[0016] If the operation years of the cascade reservoir are greater than or equal to a preset value, the actual discharge data of each period of the drawdown period of the cascade reservoir in the years is collected, and the maximum discharge constraint of each period of the cascade reservoir is obtained as follows:

[0017]

[0018] In the formula, is the maximum discharge constraint of cascade reservoir i in time period k, is the actual discharge of cascade reservoir i in time period k in jth year, and m is the operation years of cascade reservoir i;

[0019] If the operation years of the cascade reservoir is less than the preset value, according to the scheduling requirement, the discharge constraints of the cascade reservoir in each time period of the drawdown period in each year under the influence of multiple factors are analyzed, and the maximum discharge constraint of the cascade reservoir in each time period is obtained as:

[0020]

[0021] In the formula, is the discharge constraint under the influence of the overhaul of the hydropower station, is the discharge constraint under the influence of the line overhaul, is the discharge constraint under the influence of the power grid peak regulation, is the discharge constraint of the water supply scheduling requirement, is the discharge constraint of the ecological scheduling requirement.

[0022] According to the generation method of the cascade reservoir drawdown period optimal scheduling scheme provided by the application, step 3 specifically comprises:

[0023] The objective function of the cascade reservoir drawdown period optimal scheduling model is determined as:

[0024]

[0025] In the formula, G is the total target of the cascade reservoir optimal scheduling, is the power generation output of cascade reservoir i in time period k, is the abandoned water flow of cascade reservoir i in time period k, is the abandoned water quantity penalty factor of cascade reservoir i in time period k, and R is the number of cascade reservoirs;

[0026] The constraint conditions of the cascade reservoir drawdown period optimal scheduling model include:

[0027]

[0028] In the formula, is the reservoir water level of cascade reservoir i in time period k, is the reservoir water level of cascade reservoir i in time period k+1, and are the minimum and maximum reservoir water level constraints of cascade reservoir i in time period k, respectively, and ΔZ i represents the maximum allowed reservoir water level amplitude in adjacent time periods; is the discharge of cascade reservoir i in time period k, With respectively minimum and maximum outflow constraints of the cascade reservoir i at time period k;

[0029] According to long series of natural runoff data, natural runoff of each year in drawdown period is taken as the basis to carry out frequency analysis, and years corresponding to natural runoff of different frequencies are selected to represent different typical years, and different water abandonment penalty factors are set for different typical years.

[0030] According to the cascade reservoir drawdown period optimal scheduling scheme generation method provided by the application, step 4 specifically comprises:

[0031] Step 41, the initial water level process line of the first to the Rth cascade reservoir is solved by using an approximation algorithm;

[0032] Step 42, the initial water level process line of the second to the Rth cascade reservoir is fixed, the first cascade reservoir is optimized and scheduled according to the cascade reservoir optimization scheduling total target by using a step-by-step optimization algorithm, and the optimal water level process line of the first cascade reservoir is obtained;

[0033] Step 43, the optimal water level process line of the first cascade reservoir after optimization and scheduling is fixed, and the initial water level process line of the third to the Rth cascade reservoir is fixed, the second cascade reservoir is optimized and scheduled according to the cascade reservoir optimization scheduling total target by using a step-by-step optimization algorithm, and the optimal water level process line of the second cascade reservoir is obtained;

[0034] Step 44, in this way, all cascade reservoirs are traversed and optimized to obtain the optimal water level process line of all cascade reservoirs;

[0035] Step 45, when the optimal water level process lines of adjacent two cascade reservoirs are obtained, whether the values of the cascade reservoir optimization scheduling total target calculated by adjacent two times meet the following formula (1):

[0036]

[0037] δ≤δ lim (1)

[0038] In the formula, G l , G l+1 are the values of the cascade reservoir optimization scheduling total target calculated by adjacent two times, δ lim is a preset optimization target discrimination threshold;

[0039] If formula (1) is met, the optimal water level process lines of the corresponding adjacent two cascade reservoirs are output; if formula (1) is not met, step 42 is executed until formula (1) is met

[0040] According to the cascade reservoir drawdown period optimal scheduling scheme generation method provided by the application, step 5 specifically comprises:

[0041] According to the optimal water level process line of the cascade reservoir, the relative abandoned water quantity of the cascade reservoir in a typical year is counted, and whether the relative abandoned water quantity meets the following condition is judged:

[0042]

[0043] ΔW≤ΔW lim (2)

[0044] In the formula, W 弃水 is the total abandoned water quantity of the cascade reservoir in the drawdown period, W 来水 is the total inflow quantity of the lowermost cascade reservoir in the drawdown period, ΔW lim is a preset threshold value;

[0045] If the formula (2) is met, the drawdown water level and the reservoir capacity to be drawn down of the cascade reservoir in the typical year are obtained; if the formula (2) is not met, the abandoned water quantity and the reservoir capacity to be drawn down of the cascade reservoir in each period are counted, for the period in which the abandoned water quantity is greater than zero, the abandoned water quantity punishment factor of the cascade reservoir in the period is increased, and step 4 is repeatedly executed until the formula (2) is met.

[0046] According to the generation method of the cascade reservoir drawdown period optimization scheduling scheme provided by the application, step 6 specifically comprises the following steps.

[0047] Between the drawdown period starting time and the drawdown period ending time, p control time nodes are selected according to the scheduling operation needs, and

[0048]

[0049] Among them, p control time nodes are selected;

[0050] The reservoir water level and the overall reservoir capacity to be drawn down obtained by each control time node in each typical year are counted to form the drawdown period optimization scheduling scheme.

[0051] In the second aspect, the application further provides a generation device of a cascade reservoir drawdown period optimization scheduling scheme, comprising:

[0052] A collection unit is configured to collect engineering characteristic basic data and long-series natural runoff data of the cascade reservoir;

[0053] A generalization unit is configured to generalize the maximum discharge constraint of the cascade reservoir in the drawdown period under various influence factors based on the engineering characteristic basic data and the long-series natural runoff data by using a time series analysis method;

[0054] A construction analysis unit is configured to construct a cascade reservoir drawdown period optimization scheduling model considering the maximum power generation and the minimum abandoned water quantity, to perform drawdown period inflow frequency analysis, and to determine the abandoned water quantity punishment factor in different typical years.

[0055] a solving unit configured to solve the cascade reservoir drawdown period optimization scheduling model by using a step-by-step optimization algorithm combined with a successive approximation algorithm to obtain an optimal water level process line of the cascade reservoirs;

[0056] a processing unit configured to, according to the optimal water level process line and the water abandonment quantity penalty factor of different typical years, count the relative water abandonment quantity of the cascade reservoir drawdown period, and according to the size relationship between the relative water abandonment quantity and a preset threshold, adjust the water abandonment quantity penalty factor or count the water abandonment quantity and the overall water capacity to be consumed of the cascade reservoirs in each period;

[0057] a generating unit configured to, according to the scheduling operation requirement, determine different control time nodes of each cascade reservoir in different typical years, count the reservoir water level and the overall water capacity to be consumed obtained at each control time node, and form the drawdown period optimization scheduling scheme.

[0058] The method comprises the following steps: collecting the engineering characteristic basic data and long-series natural runoff data of the cascade reservoirs; generalizing the maximum discharge constraint of the cascade reservoir drawdown period under various influencing factors by using a time series analysis method; constructing a cascade reservoir drawdown period optimization scheduling model considering the maximum power generation preference and the minimum water abandonment quantity preference, performing drawdown period inflow frequency analysis, and determining the water abandonment quantity penalty factor of different typical years; solving the cascade reservoir drawdown period optimization scheduling model by using a step-by-step optimization algorithm combined with a successive approximation algorithm to obtain an optimal water level process line of the cascade reservoirs; judging the size relationship between the relative water abandonment quantity of the cascade reservoir drawdown period and a preset threshold for the model result obtained by solving, and adjusting the water abandonment quantity penalty factor as appropriate; arranging the reservoir water level and the overall water capacity to be consumed of different control time nodes of each cascade reservoir in different typical years to form the drawdown period optimization scheduling scheme. The method has the advantages of being simple and practical, reasonable and reliable, and easy to popularize. According to the characteristics of the cascade reservoir drawdown period scheduling operation, the optimal drawdown process of the cascade reservoir drawdown period under different inflow conditions is quickly given under the double optimization objectives of considering the power generation of the hydropower station and reducing the water abandonment quantity, the power generation benefit of the cascade reservoirs is improved, the method meets the operation characteristics of the actual scheduling of the cascade reservoirs, and can provide decision support for the real-time scheduling of the operation and management department of the cascade reservoirs. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0060] In the drawings:

[0061] Figure 1 The flow chart of the generation method of the optimal scheduling scheme of the drawdown period of the cascade reservoirs of the application;

[0062] Figure 2 The structural block diagram of the generation device of the optimal scheduling scheme of the drawdown period of the cascade reservoirs of the application. DETAILED DESCRIPTION

[0063] To make the objectives, technical solutions and advantages of the application clearer, the technical solutions in the application will be described below in connection with the drawings in the application. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the application.

[0064] Some embodiments of the application will be described in detail below in connection with the drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0065] The embodiment of the application provides a generation method of an optimal scheduling scheme of a drawdown period of cascade reservoirs, which can consider the optimization objectives of power generation and water abandonment of the cascade reservoirs, reasonably depict the influence of multiple factors in different stages of the drawdown period of the cascade reservoirs on power generation flow, reduce the optimization dimension disaster of the cascade reservoirs, and meet important scheduling requirements of scheduling operation and management of the drawdown period of the cascade reservoirs.

[0066] Please refer to Figure 1 The generation method of the optimal scheduling scheme of the drawdown period of the cascade reservoirs comprises the following steps:

[0067] Step 1, collecting engineering characteristic basic data and long-series natural runoff data of the cascade reservoirs;

[0068] Specifically, the engineering characteristic basic data comprises normal water storage level, water level-storage capacity curve, start and end time of the drawdown period, full generation flow, minimum discharge flow, reservoir water level amplitude constraint, tail water level relationship curve, operation water level at the end of the drawdown period (i.e. reservoir water level requirement meeting the flood control safety at the end of the drawdown period) and the like of each cascade reservoir. The time scale of the long-series natural runoff data can be ten-day average or daily average.

[0069] Step 2, based on the engineering characteristic basic data and the long-series natural runoff data, using a time series analysis method to generalize the maximum discharge flow constraint of the cascade reservoirs under multiple influence factors in the drawdown period;

[0070] In some embodiments, the multiple influence factors comprise: water power station maintenance, line maintenance, power grid peak regulation, water supply scheduling, ecological scheduling and the like.

[0071] Step 2 specifically comprises:

[0072] Step 21, determine the time step dt of the drawdown period of the cascade reservoir based on the time scale of the long series of natural runoff data;

[0073] Step 22, divide the drawdown period into n periods according to the start and end time of the drawdown period and the time step, where n = TS / dt, TS = T1-T0; in the formula, T0 is the start time of the drawdown period, T1 is the end time of the drawdown period, TS is the duration of the drawdown period, and dt is the time step of the drawdown period;

[0074] Step 23, analyze the maximum discharge constraint of each period: for the cascade reservoir i with certain dispatching operation actual data (for example, the operation years m >= 5), that is, if the operation years of the cascade reservoir are greater than or equal to the preset value, collect the actual discharge data of each period of the drawdown period of the cascade reservoir in each year j = 1, 2,..., m, k = 1, 2,..., n, and the maximum discharge constraint of the cascade reservoir i in period k is:

[0075]

[0076] in the formula, is the maximum discharge constraint of the cascade reservoir i in period k, is the actual discharge of the cascade reservoir i in period k in the jth year, and m is the operation years of the cascade reservoir i;

[0077] For the cascade reservoir whose dispatching operation years do not meet the above requirements, that is, if the operation years of the cascade reservoir are less than the preset value, analyze the discharge constraint of the cascade reservoir in each period of the drawdown period under the influence of power plant maintenance according to the dispatching requirements Discharge constraint under the influence of line maintenance Discharge constraint under the influence of grid peak regulation Discharge constraint required by water supply dispatching Discharge constraint required by ecological dispatching The maximum discharge constraint of the cascade reservoir i in period k is:

[0078]

[0079] Step 3, construct a cascade reservoir drawdown period optimal dispatching model considering the maximum power generation and the minimum water abandonment, analyze the drawdown period inflow frequency, and determine the water abandonment penalty factor in different typical years;

[0080] In some embodiments, step 3 specifically includes:

[0081] Step 31, determine the objective function of the cascade reservoir drawdown period optimal dispatching model as:

[0082]

[0083] In the formula, G is the total target of the cascade reservoir optimization scheduling, E 发电 is the power generation target of the cascade reservoir optimization scheduling, W 弃水 is the abandoned water target of the cascade reservoir optimization scheduling, and θ is the abandoned water punishment factor, is the power generation output of the cascade reservoir i at the time period k, is the abandoned water flow of the cascade reservoir i at the time period k, is the abandoned water punishment factor of the cascade reservoir i at the time period k, and R is the number of the cascade reservoirs.

[0084] Step 32, the constraint conditions of the cascade reservoir drawdown period optimization scheduling model include:

[0085] Reservoir water level constraint condition

[0086]

[0087] In the formula, is the reservoir water level of the cascade reservoir i at the time period k, is the reservoir water level of the cascade reservoir i at the time period k+1, and are the minimum and maximum reservoir water level constraints of the cascade reservoir i at the time period k, respectively, and ΔZ i represents the maximum allowed reservoir water level amplitude in the adjacent time period. In the drawdown period, the dead water level is generally considered; if there is no special requirement, the normal water level is generally considered at the initial time.

[0088] Outflow constraint condition

[0089]

[0090] In the formula, is the outflow of the cascade reservoir i at the time period k, and are the minimum and maximum outflow constraints of the cascade reservoir i at the time period k, respectively; the minimum outflow is controlled according to the scheduling regulation approval, and the maximum outflow is controlled according to the maximum outflow determined in step 2.

[0091] Initial and final water level boundary condition

[0092] The starting water level of the cascade reservoir i at the initial time period is generally controlled according to the normal water level; and the control water level of the cascade reservoir i at the final time period n of the drawdown period is generally considered according to the flood control water level.

[0093] Step 33, according to the long series of natural runoff data, the natural runoff of each year is analyzed, and the years corresponding to different frequencies of natural runoff are selected to represent different typical years, and different penalty factors of water abandonment are set for different typical years;

[0094] Alternatively, for the long series of natural runoff data collected in step 1 (assuming that the data series has y years), the natural runoff of each year is analyzed, and the years corresponding to 10%, 50%, and 90% frequencies of natural runoff are selected to represent typical years of abundance, flatness, and dryness, respectively; and different penalty factors of water abandonment are set for different typical years.

[0095] Step 4, the step-by-step optimization algorithm (POA) is combined with the successive approximation algorithm (DPSA) to solve the cascade reservoir drawdown period optimization scheduling model, and the optimal water level process line of the cascade reservoir is obtained;

[0096] Specifically, step 4 specifically includes:

[0097] Step 41, the initial water level process line of the first to the Rth cascade reservoir is solved using the approximation algorithm (DP algorithm).

[0098] Step 42, the initial water level process line of the second to the Rth cascade reservoir is fixed, and the POA algorithm is used to optimize the scheduling of the first cascade reservoir, and the optimal water level process line of the first cascade reservoir is obtained.

[0099] Step 43, the optimal water level process line of the first cascade reservoir after optimization scheduling is fixed, and the initial water level process line of the third to the Rth cascade reservoir is fixed, and the POA algorithm is used to optimize the scheduling of the second cascade reservoir according to the total optimization scheduling target of the cascade reservoir, and the optimal water level process line of the second cascade reservoir is obtained.

[0100] Step 44, in this way, all cascade reservoirs are optimized to obtain the optimal water level process line of all cascade reservoirs.

[0101] Step 45, when the optimal water level process lines of adjacent two cascade reservoirs are obtained, whether the values of the total optimization scheduling target of the cascade reservoir calculated by the adjacent two times satisfy:

[0102]

[0103] δ≤δ lim (1)

[0104] In the formula, G l , G l+1respectively, are the values of the total target of the cascade reservoir optimal scheduling calculated in the adjacent two times, and δ lim is a preset optimal target discrimination threshold value;

[0105] If formula (1) is satisfied, the optimal water level process line of the corresponding adjacent two cascade reservoirs is output; if formula (1) is not satisfied, step 42 is executed until formula (1) is satisfied.

[0106] The present application introduces a preset optimal target discrimination threshold value δ lim to judge whether the value G l+1 of the total target of the cascade reservoir optimal scheduling calculated this time meets the accuracy requirement compared with the value G l of the total target of the cascade reservoir optimal scheduling calculated last time, if δ≤δ lim is satisfied, the calculation is stopped, and the optimal water level process line of the cascade reservoir, i.e., the state change process, is output; otherwise, the iteration calculation is continued until the iteration requirement is met.

[0107] Step 5: According to the optimal water level process line and the water abandonment quantity penalty factor of different typical years, the relative water abandonment quantity of the cascade reservoir drawdown period is counted year by year, and according to the size relationship between the relative water abandonment quantity and the preset threshold value, the water abandonment quantity penalty factor is adjusted or the water abandonment quantity and the to-be-discharged reservoir capacity of the cascade reservoir in each period are counted.

[0108] In some embodiments, step 5 specifically includes:

[0109] Step 51: According to the optimal water level process line of the cascade reservoir, the relative water abandonment quantity of the cascade reservoir drawdown period is counted year by year, and it is judged whether the relative water abandonment quantity meets:

[0110]

[0111] ΔW≤ΔW lim (2)

[0112] In the formula, W 弃水 is the total water abandonment quantity of the cascade reservoir drawdown period, W 来水 is the total inflow quantity of the lowest cascade reservoir drawdown period, ΔW lim is a preset threshold value;

[0113] Step 52: If formula (2) is satisfied, the drawdown water level and the to-be-discharged reservoir capacity of the cascade reservoir drawdown period in the typical year are obtained; if formula (2) is not satisfied, the water abandonment quantity and the to-be-discharged reservoir capacity of the cascade reservoir in each period are counted, the water abandonment quantity penalty factor of the cascade reservoir in the period with the water abandonment quantity greater than zero is increased, and step 4 is repeatedly executed until formula (2) is satisfied.

[0114] The present application introduces a threshold value ΔW lim, that is, the preset threshold value. Based on step 4, the amount of water abandoned during the drawdown period of the cascade reservoirs is counted in each typical year. 弃水 and ΔW. Determine whether the relative water discharge ΔW of the cascade reservoirs in a typical year is less than or equal to ΔW lim , if ΔW≤ΔW lim , then the simulation results of the cascade reservoirs in this typical year meet the final requirements; if ΔW>ΔW lim , further optimize the cascade decline process of this typical year, that is, for ΔW>ΔW lim In a typical year, the amount of water discharged from the cascade reservoirs in statistical period k (k = 1, 2, ..., n) is δW 弃水,l and the storage capacity to be eliminated of the cascade reservoirs ΔV l ; For δW 弃水,l >0, increase the penalty factor for the amount of water abandoned by the cascade reservoir in period k (It can be considered as dθ is increased each time), and step 4 is repeated to perform the optimal scheduling simulation calculation for the typical year until ΔW≤ΔW is satisfied. lim .

[0115] Step 6: According to the needs of scheduling and operation, determine the different control time nodes of each cascade reservoir in different typical years, calculate the reservoir water level and overall storage capacity to be drawn down at each control time node, and form an optimized scheduling plan for the drawdown period.

[0116] In some embodiments, step 6 specifically includes:

[0117] Step 61: between the start time T0 of the ebb period and the end time T1 of the ebb period, select p important control time nodes according to the scheduling operation needs. and

[0118]

[0119] Step 62: For each of the selected typical years of high water, normal water and low water, the reservoir water level and overall storage capacity to be drawn from each control time node of each typical year are statistically analyzed to form an optimized scheduling plan for the drawdown period.

[0120] Based on the same inventive concept, another embodiment of the present invention provides a device for generating an optimized scheduling scheme for the drawdown period of a cascade reservoir. The device corresponds to the method of the aforementioned embodiment, such as Figure 2 As shown, the device includes:

[0121] Collection unit, used to collect basic data on engineering characteristics of cascade reservoirs and long-series natural runoff data;

[0122] The generalization unit is used to generalize the maximum outflow constraints of cascade reservoirs under various influencing factors during the drawdown period using time series analysis based on basic engineering characteristic data and long-term natural runoff data;

[0123] The construction analysis unit is configured to construct a cascade reservoir drawdown period optimal scheduling model considering maximum power generation and minimum water abandonment, to analyze the inflow frequency of the drawdown period, and to determine the water abandonment penalty factor in different typical years;

[0124] The solving unit is configured to solve the cascade reservoir drawdown period optimal scheduling model by using a step-by-step optimization algorithm combined with a successive approximation algorithm, to obtain the optimal water level process line of the cascade reservoirs;

[0125] The processing unit is configured to, according to the optimal water level process line and the water abandonment penalty factor in different typical years, statistically determine the relative water abandonment of the cascade reservoir drawdown period in each typical year, and according to the size relationship between the relative water abandonment and a preset threshold, adjust the water abandonment penalty factor or statistically determine the water abandonment and the reservoir capacity to be consumed in each period of the cascade reservoirs;

[0126] The generating unit is configured to, according to the scheduling operation needs, determine different control time nodes of each cascade reservoir in different typical years, statistically determine the reservoir water level and the overall reservoir capacity to be consumed at each control time node, and form an optimal scheduling scheme for the drawdown period.

[0127] The following is a specific embodiment of the present application.

[0128] Taking four cascade reservoirs in the Jinshajiang River Basin as an example, the specific process of the generating method of the cascade reservoir drawdown period optimal scheduling scheme provided by the present application is as follows:

[0129] 1. Collect the normal storage level, water level-storage capacity curve, start and end time of the drawdown period, full generation flow, minimum discharge flow, reservoir water level amplitude constraint, tail water level relationship curve, final operation water level of the drawdown period, and ten-day average long series natural runoff data (1959-2014) of the four cascade reservoirs, wherein the normal storage level, start and end time of the drawdown period, full generation flow, minimum discharge flow, and final operation water level of the drawdown period of the four cascade reservoirs are shown in Table 1.

[0130] Table 1. Part of the engineering characteristic parameters of the four cascade reservoirs

[0131]

[0132] 2. The time step dt for calculation is determined to be ten days, and the calculation period is n = 21; by collecting the historical scheduling operation data of the cascade reservoirs and the influence of different scheduling requirements and maintenance on the discharge flow, the maximum discharge flow constraints of different time periods and different cascade reservoirs under the influence of multiple factors such as drawdown period hydropower station maintenance, line maintenance, power grid peak regulation, water supply scheduling, and ecological scheduling are analyzed, and the specific values are shown in Table 2.

[0133] Table 2. Maximum generation flow constraint coefficient table of the four cascade reservoirs

[0134]

[0135]

[0136] 3. Constructing the optimal scheduling model of the drawdown period of cascade reservoirs considering the preference of maximum power generation and minimum water abandonment; determining the constraint conditions of reservoir water level, outflow, initial and final water level of the drawdown period of cascade reservoirs; selecting the 10%, 50%, and 90% frequency years of natural runoff in 1978, 1961, and 1982 respectively to represent the typical years of wet, normal, and dry years according to the frequency analysis of the total runoff of the drawdown period based on the long series of natural runoff from 1959 to 2014; preliminarily determining the penalty factor θ of water abandonment of each cascade reservoir in different periods of different typical years: θ = 0.02 for the period from December 1 to April 30, i.e. period 1 to 15; θ = 0.08 for the period from May 1 to June 30, i.e. period 16 to 21; the above is referred to as "Scheme 1".

[0137] 4. Determining the optimization target discrimination threshold δ lim = 0.01%, using the constructed optimal scheduling model of the drawdown period of cascade reservoirs to simulate different typical years, outputting and arranging the simulation results of different typical years, and Table 3 is the power generation and water abandonment of the drawdown period of each cascade reservoir in the typical years of Scheme 1.

[0138] Table 3. Power generation and water abandonment of the drawdown period of each cascade reservoir in the typical years of Scheme 1

[0139]

[0140] 5. Analyzing the water abandonment in each typical year, for 1982, there is no water abandonment in the drawdown period, and Scheme 1 is the recommended scheme; for the typical years of 1978 and 1961 in which there is water abandonment in the drawdown period according to the simulation results of Scheme 1, determining the threshold ΔW lim = 2% of the acceptable relative water abandonment of the drawdown period of cascade reservoirs, and the relative water abandonment ΔW of 1978 and 1961 is 6.53% and 3.32% respectively.

[0141] Further increase the water penalty factor θ (each increase dθ, where the calculation period 1 to 15 single step dθ = 0.02, the calculation period 16 to 21 single step dθ = 0.08), through iterative calculation and determination, when the calculation period 1 to 15 θ = 0.06, the calculation period 16 to 21 θ = 0.24 (referred to as "scheme 2"), 1961 cascade reservoir drawdown period relative water quantity ΔW is 0.01%, down to the acceptable threshold range, scheme 2 is its recommended scheme; 1978 cascade reservoir drawdown period relative water quantity ΔW is 4.36%, need further iterative calculation. Table 4 is the total power generation and water quantity of each cascade reservoir drawdown period in the typical year of scheme 2, comparing table 3 and table 4, for 1978, the power generation is reduced by 0.2%, but the water quantity is reduced by 33.2%; for 1961, the power generation is reduced by 0.2%, and the water quantity is reduced by 99.6%.

[0142] Table 4, the power generation and water quantity of each cascade reservoir drawdown period in the typical year of scheme 2

[0143]

[0144] For the wet year 1978, still further increase the water penalty factor θ, through iterative calculation and determination, when the calculation period 1 to 15 θ = 0.8, the calculation period 16 to 21 θ = 3.2 (referred to as "scheme 3"), 1978 cascade reservoir drawdown period relative water quantity ΔW is 2.00%, down to the acceptable threshold range, scheme 3 is its recommended scheme. Table 5 is the total power generation and water quantity of each cascade reservoir drawdown period in the typical year of scheme 3, comparing table 3 and table 5, for 1978, the power generation is reduced by 1.7%, but the water quantity is reduced by 69.2%.

[0145] Table 5, the power generation and water quantity of each cascade reservoir drawdown period in the typical year of scheme 3

[0146]

[0147]

[0148] 6, select January 1, February 1, March 1, April 1, May 1, June 1, June 10, June 20 and other important control time nodes; in turn, statistics of each typical year recommended scheme under the above different time nodes calculated reservoir water level, the whole to be consumed reservoir capacity and other indicators, form the recommended drawdown period optimization scheduling scheme, see table 6.

[0149] Table 6, the reservoir water level and the whole to be consumed reservoir capacity distribution table of each cascade reservoir of the recommended scheme

[0150]

[0151]

[0152] Note: The negative value of the whole cascade reservoir storage capacity indicates the reservoir capacity below the flood control water level.

[0153] In summary, the generation method and device of the cascade reservoir drawdown period optimal scheduling scheme provided by the application have the following beneficial effects:

[0154] 1. Compared with the single optimal scheduling mode of maximizing power generation or minimizing water abandonment, the optimal scheduling method for coordinating power generation and water abandonment provided by the application can better consider both types of optimization objectives, and can also adjust the optimal scheduling scheme according to the size of water abandonment.

[0155] 2. The maximum outflow constraints of different time periods and different cascade reservoirs under the influence of multiple factors such as water power station maintenance, line maintenance, power grid peak regulation, water supply scheduling, ecological scheduling, etc. during the drawdown period can be fully combined with historical scheduling operation characteristics and actual scheduling requirements, which conforms to the actual scheduling and operation characteristics of cascade reservoirs.

[0156] 3. The application solves the cascade reservoir drawdown period optimal scheduling model by combining the progressive optimization algorithm (POA) with the successive approximation algorithm (DPSA), which can eliminate the problem of too long calculation period caused by "dimension disaster", and can make the optimization result as close to the global optimal solution as possible, and the method has the advantages of good solving effect and fast calculation speed.

[0157] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. The specification and examples given herein are intended as illustrative only and not intended to limit the scope of the present application. Certain features of the application are described above as belonging to one or more of the embodiments of the application. It is intended that only those features of the application that are truly essential to the understanding of the application and claims as a whole are described above. It is intended that the scope of the application be limited only by the claims, and that the claims be interpreted in the light of this specification and the practice of the embodiments disclosed herein.

Claims

1. A method for generating an optimized scheduling scheme for a cascade reservoir drawdown period, characterized in that: include: Step 1: Collect basic data on engineering characteristics of cascade reservoirs and long-term natural runoff data; Step 2: Based on the basic data of engineering characteristics and long-term natural runoff data, a time series analysis method is used to generalize the maximum outflow constraints of the cascade reservoirs under various influencing factors during the drawdown period; Step 3: Construct an optimal scheduling model for the drawdown period of cascade reservoirs that takes into account both maximum power generation and minimum water abandonment, analyze the frequency of water inflow during the drawdown period, and determine the penalty factors for water abandonment in different typical years; Step 4: Solve the drawdown optimization scheduling model of the cascade reservoirs by combining a stepwise optimization algorithm with a successive approximation algorithm to obtain the optimal water level process line of the cascade reservoirs; Step 5: Based on the optimal water level process line and the water abandonment penalty factors of different typical years, the relative water abandonment of the cascade reservoirs during the drawdown period is counted in each typical year. According to the relationship between the relative water abandonment and a preset threshold, the water abandonment penalty factor is adjusted or the water abandonment and the storage capacity to be abandoned of the cascade reservoirs in each period are counted; Step 6: Determine different control time nodes for each cascade reservoir in different typical years based on scheduling and operation needs, calculate the reservoir water level and overall storage capacity to be drawn down at each control time node, and form an optimized scheduling plan for the drawdown period; The various influencing factors include hydropower station maintenance, line maintenance, power grid peak regulation, water supply scheduling, and ecological scheduling; The step 4 specifically includes: Step 41: Use the approximation algorithm to solve the first to the R Initial water level process lines of cascade reservoirs; R is the number of cascade reservoirs; Step 42, fix the second to the R The initial water level process line of each cascade reservoir is obtained, and the first cascade reservoir is optimized according to the overall goal of the optimized operation of the cascade reservoirs using a stepwise optimization algorithm to obtain the optimal water level process line of the first cascade reservoir; Step 43: Fix the optimal water level process line of the first cascade reservoir after optimization and dispatch, and fix the optimal water level process line of the third to the third cascade reservoir. R The initial water level process line of the first cascade reservoir is obtained, and the stepwise optimization algorithm is continued to be used to optimize the operation of the second cascade reservoir according to the overall goal of the optimized operation of the cascade reservoirs, so as to obtain the optimal water level process line of the second cascade reservoir; Step 44: Similarly, traverse and optimize all cascade reservoirs to obtain the optimal water level process lines of all cascade reservoirs; Step 45: When obtaining the optimal water level process lines of two adjacent cascade reservoirs, determine whether the values ​​of the total target of the cascade reservoir optimization operation calculated twice in succession meet the following conditions: （1） Where, are the values ​​of the total target of the optimized operation of the cascade reservoirs calculated twice in succession, It is the preset optimization target discrimination threshold; If the equation (1) is satisfied, the optimal water level process lines of the corresponding two adjacent cascade reservoirs are output; if the equation (1) is not satisfied, step 42 is executed until the equation (1) is satisfied.

2. The method for generating an optimized scheduling scheme for the drawdown period of cascade reservoirs according to claim 1 is characterized in that: The basic data of engineering characteristics include the normal water storage level of each cascade reservoir, water level and storage capacity curve, start and end time of the drawdown period, full discharge flow, minimum discharge flow, reservoir water level variation constraint, tail water level relationship curve, and operating water level at the end of the drawdown period.

3. The method for generating an optimized scheduling scheme for the drawdown period of cascade reservoirs according to claim 2 is characterized in that: The step 2 specifically includes: Determine the time step of the drawdown period of cascade reservoirs based on the time scale of long series natural runoff data; According to the start and end time and time step of the decline period, the decline period is divided into n time periods, where: n = TS / dt , TS = T 1- T 0; where T 0 is the start time of the decline period, T 1 is the end time of the decline period, TS is the duration of the decline period, dt is the time step of the decline period; If the operating years of the cascade reservoirs are greater than or equal to the preset value, the actual outflow flow data of the cascade reservoirs in each period of the drawdown period over the years are collected, and the maximum outflow flow constraint of the cascade reservoirs in each period is obtained as follows: Where, is the maximum outflow constraint of cascade reservoir i in period k, is the actual outflow of cascade reservoir i in year j during period k, and m is the number of years of operation of cascade reservoir i; If the operating years of the cascade reservoirs are less than the preset value, then according to the scheduling requirements, the outflow constraints of the cascade reservoirs under various influencing factors in each period of the drawdown period are analyzed, and the maximum outflow constraints of the cascade reservoirs in each period are obtained as follows: Where, is the outflow constraint under the influence of hydropower station maintenance, is the outbound flow constraint under the influence of line maintenance, is the outbound flow constraint under the influence of power grid peak regulation, is the outflow constraint required by water supply scheduling, It is the outbound flow constraint required by ecological scheduling.

4. The method for generating an optimized scheduling scheme for the drawdown period of cascade reservoirs according to claim 3 is characterized in that: The step 3 specifically includes: The objective function of the optimal scheduling model for the cascade reservoir drawdown period is determined as follows: Where, G To optimize the overall operation target of cascade reservoirs, cascade reservoirs i In the period k The power output, cascade reservoirs i In the period k The abandoned water flow, cascade reservoirs i In the period k The penalty factor for abandoned water volume; The constraints for determining the optimal scheduling model for the drawdown period of the cascade reservoirs include: Where, cascade reservoirs i In the period k The reservoir water level, cascade reservoirs i In the period k+ 1 reservoir water level, and Cascade reservoirs i In the period k The minimum and maximum reservoir water level constraints, Indicates the maximum allowable reservoir water level fluctuation within adjacent time periods; cascade reservoirs i In the period k Outbound traffic, and Cascade reservoirs i In the period k Minimum and maximum outbound flow constraints; According to the long series of natural runoff data, frequency analysis is carried out based on the natural runoff volume in the drawdown period of each year. Years corresponding to different frequencies of natural runoff volume are selected to represent different typical years. Different water abandonment penalty factors are set for different typical years.

5. The method for generating an optimized scheduling scheme for the drawdown period of cascade reservoirs according to claim 1 is characterized in that: The step 5 specifically includes: Based on the optimal water level process line of the cascade reservoirs, the relative water discharge volume of the cascade reservoirs during the drawdown period is calculated in each typical year to determine whether the relative water discharge volume meets the following requirements: Where, is the total amount of water discharged from the cascade reservoirs during the drawdown period, is the total water inflow of the downstream cascade reservoir during the drawdown period, is the preset threshold; If formula (2) is satisfied, the drawdown water level and the storage capacity to be drawn during the drawdown period of the cascade reservoirs in that typical year are obtained; if formula (2) is not satisfied, the amount of water abandoned and the storage capacity to be drawn during each period of the cascade reservoirs are counted. For the period when the amount of water abandoned is greater than zero, the penalty factor for the amount of water abandoned during that period of the cascade reservoirs is increased, and step 4 is repeated until formula (2) is satisfied.

6. The method for generating an optimized scheduling scheme for the drawdown period of cascade reservoirs according to claim 5, characterized in that: The step 6 specifically includes: Between the start time and the end time of the decline period, select p control time nodes, and in, for p Control time nodes; The reservoir water level and overall storage capacity to be drawn down are calculated at each control time node in each typical year to form an optimized scheduling plan for the drawdown period.

7. A device for generating an optimized scheduling scheme for a cascade reservoir drawdown period, characterized in that: include: Collection unit, used to collect basic data on engineering characteristics of cascade reservoirs and long-series natural runoff data; A generalization unit is used to generalize the maximum outflow constraints of the cascade reservoirs under various influencing factors during the drawdown period using a time series analysis method based on the basic data of the engineering characteristics and a long series of natural runoff data; Construct an analysis unit to build an optimal scheduling model for cascade reservoirs during the drawdown period that balances maximum power generation with minimum water abandonment, analyze the frequency of water inflow during the drawdown period, and determine the penalty factors for water abandonment in different typical years; A solving unit, configured to solve the drawdown optimization scheduling model of the cascade reservoirs by combining a stepwise optimization algorithm with a successive approximation algorithm, and obtain an optimal water level process line of the cascade reservoirs; a processing unit configured to calculate the relative amount of water abandoned during the drawdown period of the cascade reservoirs in each typical year based on the optimal water level process line and the penalty factors for water abandoned in different typical years, and to adjust the penalty factors for water abandoned or calculate the amount of water abandoned and the storage capacity to be abandoned of the cascade reservoirs in each time period based on the relationship between the relative amount of water abandoned and a preset threshold; The generation unit is used to determine the different control time nodes of each cascade reservoir in different typical years according to the scheduling and operation needs, calculate the reservoir water level and overall storage capacity to be drawn at each control time node, and form an optimized scheduling plan for the drawdown period; The various influencing factors include hydropower station maintenance, line maintenance, power grid peak regulation, water supply scheduling, and ecological scheduling; The method of combining a stepwise optimization algorithm with a successive approximation algorithm to solve the drawdown period optimization scheduling model of the cascade reservoirs and obtain the optimal water level process line of the cascade reservoirs includes: Step 41: Use the approximation algorithm to solve the first to the R Initial water level process lines of cascade reservoirs; R is the number of cascade reservoirs; Step 42, fix the second to the R The initial water level process line of each cascade reservoir is obtained, and the first cascade reservoir is optimized according to the overall goal of the optimized operation of the cascade reservoirs using a stepwise optimization algorithm to obtain the optimal water level process line of the first cascade reservoir; Step 43: Fix the optimal water level process line of the first cascade reservoir after optimization and dispatch, and fix the optimal water level process line of the third to the third cascade reservoir. R The initial water level process line of the first cascade reservoir is obtained, and the stepwise optimization algorithm is continued to be used to optimize the operation of the second cascade reservoir according to the overall goal of the optimized operation of the cascade reservoirs, so as to obtain the optimal water level process line of the second cascade reservoir; Step 44: Similarly, traverse and optimize all cascade reservoirs to obtain the optimal water level process lines of all cascade reservoirs; Step 45: When obtaining the optimal water level process lines of two adjacent cascade reservoirs, determine whether the values ​​of the total target of the cascade reservoir optimization operation calculated twice in succession meet the following conditions: （1） Where, are the values ​​of the total target of the optimized operation of the cascade reservoirs calculated twice in succession, It is the preset optimization target discrimination threshold; If the equation (1) is satisfied, the optimal water level process lines of the corresponding two adjacent cascade reservoirs are output; if the equation (1) is not satisfied, step 42 is executed until the equation (1) is satisfied.

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