CN115730724B - Cascade hydropower station joint scheduling method based on maximization of non-stored electric energy - Google Patents
Cascade hydropower station joint scheduling method based on maximization of non-stored electric energy Download PDFInfo
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Abstract
The invention discloses a cascade hydropower station joint scheduling method based on maximization of non-stored electric energy, which comprises the following steps: s1, constructing a target scheduling function meeting various constraint conditions by taking the maximum utilization of the non-water storage capacity of the cascade hydropower station as a direction; s2, analyzing an objective function based on cascade hydropower station joint scheduling; s3, solving an objective function to obtain an optimized scheduling process of each power station in the cascade hydropower station; the cascade hydropower station joint scheduling method provided by the invention is a cascade hydropower station optimal scheduling model based on maximization of the non-stored electric energy, which is constructed by taking the utilization of the non-stored water capacity of a reservoir as a starting point, can improve the power generation utilization rate of the non-stored water capacity of the cascade hydropower station, indirectly improves the saving and utilization of water resources, and has the effect of increasing the generated energy of the cascade hydropower station.
Description
Technical Field
The invention relates to the technical field of optimal scheduling of hydropower stations, in particular to a cascade hydropower station joint scheduling method based on maximization of non-stored electric energy.
Background
The current cascade hydropower station optimal scheduling method is mainly developed from the following aspects: the cascade hydropower station has the greatest total power generation amount, considers various constraint conditions, faces the electric market, improves a scheduling algorithm, is based on multiple targets and the like. The scheduling method provided herein aims at increasing the electric energy without accumulating in terms of improving the water utilization rate.
The water storage type hydropower station with a certain regulating capacity is characterized in that the water quantity for generating and producing the power consists of two parts: one part is water supply amount which is supplemented by the water storage capacity (regulating the water storage capacity) of the water storage tank to meet the load demand of the power grid, and the generated electric energy can be called water storage electric energy; the other part is the non-stored water quantity which flows through the reservoir and is directly used for generating electricity, and the generated electricity is called non-stored electricity. The magnitude of the stored electric energy is determined by the magnitude of the reservoir capacity, which is a more definite value; the electric energy is not greatly influenced by the change of the power generation water head in the process of reservoir regulation and power peak regulation.
The reservoir characteristics of each hydropower station are different, the water head change caused by the same amount of electric energy is different, and the water head change of the hydropower station in any period further affects the water head which can be utilized by the water storage capacity in the subsequent period, so that the output and the generated energy in the subsequent period are changed. Therefore, how to reasonably distribute the output of each scheduling period according to the load requirement of the power system so that the whole cascade hydropower station generates power under the condition of the largest water head as possible, thereby realizing the maximum combined total power generation of the cascade hydropower station and solving the problem to be solved urgently.
Disclosure of Invention
The invention aims to overcome the defects, and provides a cascade hydropower station joint scheduling method based on maximization of non-stored electric energy, which can improve the power generation utilization rate of non-stored water capacity of a cascade hydropower station, indirectly improve the saving and utilization of water resources and has the effect of increasing the generated energy of the cascade hydropower station.
The invention aims to solve the technical problems, and adopts the technical scheme that: a cascade hydropower station joint scheduling method based on maximization of non-stored electric energy comprises the following steps:
s1, constructing a target scheduling function meeting various constraint conditions by taking the maximum utilization of the water storage capacity of the cascade hydropower station as a direction;
s2, analyzing an objective function based on cascade hydropower station joint scheduling;
and S3, solving an objective function to obtain an optimized scheduling process of each power station in the cascade hydropower station.
Preferably, in S1, the objective function expression is:
wherein: e (E) Not store it The method comprises the steps of storing no electric energy for the t period of an ith hydropower station; n is the number of cascade hydropower stations; t is the number of scheduling period time periods; f (f) i The power coefficient of the ith hydropower station; h it An average power generation water head of the ith period of the ith hydropower station; q (Q) Not store it For the ith hydropower stationThe non-accumulated flow of the t-th period; Δt is the interval of the period.
Preferably, the constraint condition of the objective function includes: the method comprises the following steps of water balance equation, reservoir water level constraint, ex-warehouse flow constraint, hydraulic connection constraint, power station output constraint, ex-warehouse flow equation, power station output lifting constraint and electric power balance equation.
Preferably, in S2, the differential analysis of the objective function is as follows:
wherein d ΣE Not store it The method is characterized in that the non-electric storage energy variation of the cascade hydropower station in a dispatching period is obtained; dH (dH) it The reservoir storage depth of the ith period of the ith hydropower station; w (W) Not store it Is the no water storage capacity of the ith period of the ith hydropower station.
Preferably, in the water supply process, the reservoir has a water-level-fluctuating trend, the power generation water head is lowered in a following way, and d sigma E Not store it Representing the loss of the step hydropower station in the electric energy not stored in the dispatching period, wherein the smaller the loss is, the larger the electric energy not stored in the step hydropower station is;
1) The system demand load is provided by the non-accumulation force and the water-discharge supplementary force of the cascade power station together, and the balance equation is as follows:
wherein N is Library it Supplementing the output for the water discharge of the ith period of the ith hydropower station; n (N) Not store it A non-accumulating force for the ith period of the ith hydropower station; n (N) Is jt The method comprises the steps of setting the required load of a jth period of a jth power grid system; n is the number of cascade hydropower stations; n is the number of power grid systems accessed by the cascade hydropower station;
2) The water discharge supplementary output is commonly born by all hydropower stations in the cascade hydropower stations, and the flow generated by the water discharge supplementary output of all the power stations is as follows:
further, the reservoir storage depth dH of the t period is obtained it ：
In which Q Library it Supplementing flow for the water discharged in the t period of the ith hydropower station; s is S Library it An average pool area for a nth time period of an ith hydropower station; h it Generating water head for the t period of the ith hydropower station; dV (dV) it The reservoir capacity variation of the ith hydropower station in the ith period is the reservoir capacity variation of the ith period; dH (dH) it The reservoir storage depth of the ith period of the ith hydropower station;
3) In the whole cascade hydropower station, except that the non-water storage capacity of the upstream first reservoir is determined by water supply, the non-water storage capacity of the rest reservoirs after the t-th period is composed of three parts, namely: the functional expressions of the water storage capacity after the t period of the first reservoir, the water quantity stored in the upstream reservoir after the t period of the upstream reservoir and the water storage capacity after the t period of the two hydropower stations are as follows:
in which W is Not store it No water storage capacity for the ith period of the ith hydropower station; w (W) Not store 1t No water storage capacity for the t period of the 1 st hydropower station; w (W) Non-accumulating yt No water storage is generated for the interval of the t period of the y-th hydropower station; v (V) yt The water quantity stored in the storage capacity is developed after the nth period of the y-th hydropower station.
Preferably, the formulas (5) and (6) are substituted into the formula (2), and the water supply process cascade hydropower station water discharge supplementing output distribution function is as follows:
by reasonably distributing the complementary output N of each hydropower station of the cascade Library it Let d sigma E Not store it And obtaining the minimum value so that the loss of the step hydropower station for not storing electric energy is minimum, and the electric energy generated by the equivalent water is maximum, thereby realizing the maximum total power generation of the step hydropower station combined operation.
Preferably, in the water storage process, the reservoir is in an ascending trend, the power generation water head is lifted up, and d sigma E is adopted Not store it Representing the increment of the step hydropower station which does not store electric energy in the dispatching period, wherein the larger the increment is, the larger the electric energy obtained by the step hydropower station is;
1) The system demand load is provided by the non-accumulating force of the cascade power station, and the equation is as follows:
wherein N is Not store it A non-accumulating force for the ith period of the ith hydropower station; n (N) Is jt The method comprises the steps of setting the required load of a jth period of a jth power grid system;
2) The water storage of each hydropower station in the cascade hydropower station is combined, and the water storage flow of each hydropower station is as follows:
further, the reservoir storage depth dH of the t period is obtained it ：
In which Q Storage it The water storage flow of the ith period of the ith hydropower station; s is S Library it An average pool area for a nth time period of an ith hydropower station; dV (dV) it The reservoir capacity variation of the ith hydropower station in the ith period is the reservoir capacity variation of the ith period; dH (dH) it The reservoir storage depth of the ith period of the ith hydropower station;
3) The equilibrium equation of the water storage capacity of the cascade hydropower station in the water storage process is as follows:
further, the functional expression of the water storage capacity in the t period is:
W storage of yt ＝Q Storage of yt Δt y∈i (12)
In which W is Not store it No water storage capacity for the ith period of the ith hydropower station; w (W) Warehouse-in 1t The water quantity is the warehouse entry water quantity of the 1 st hydropower station in the t period; w (W) Interval yt Water is supplied to the interval of the t period of the y-th hydropower station; w (W) Storage of yt The water storage capacity of the nth period of the nth hydropower station is the water storage capacity of the nth period of the nth hydropower station; q (Q) Storage of yt And the water storage flow of the nth period of the nth hydropower station is the water storage flow of the nth period of the nth hydropower station.
Preferably, equations (10), (11) and (12) are substituted into equation (2), and the water storage distribution function of the cascade hydropower station in the water storage process is as follows:
by reasonably distributing the water storage quantity Q of each hydropower station of the cascade Storage it Let d sigma E Not store it And the maximum value is obtained, so that the increment of the step hydropower station for not storing electric energy is maximum, the same electric energy is produced, and the water consumption is minimum, thereby realizing the maximum total power generation of the step hydropower station combined operation.
Preferably, in the step S3, the POA algorithm is used to solve, decompose the objective function into a plurality of two-stage optimization solutions, and obtain an optimal solution meeting the requirement after a plurality of iterative computations
Preferably, the S3 specifically is: decomposing the multi-stage optimization problem into a plurality of two-stage optimization problems, optimizing all the two stages one by one, and finally obtaining an optimal solution meeting the precision requirement after multiple iterations, wherein the solving process comprises four steps: selecting an initial decision sequence, and establishing an initial scheduling line by taking the water level of a hydropower station reservoir as an initial sequence; two-stage optimizing; iterative calculation; and (5) judging the precision.
Compared with the prior art, the method has the beneficial technical effects that: the method is an optimized scheduling method aiming at improving the power generation utilization of the cascade hydropower station without water storage, and under the condition that various constraint conditions are met, the optimized scheduling process of each cascade hydropower station is determined, so that the electric energy without water storage of the cascade hydropower station is maximized, and the maximum total power generation of the cascade hydropower station is realized; the power generation utilization rate of the cascade hydropower station without water storage capacity is improved, the water resource saving and utilization are indirectly improved, and the cascade hydropower station has the function of increasing the power generation capacity of the cascade hydropower station; compared with the traditional scheduling mode, the scheduling model provided by the invention can reasonably arrange the storage and release processes and the power generation output of each power station of the cascade according to the change of the load demand of a power grid, so that the power generation utilization rate of the water without the water storage is improved as much as possible, the maximum total combined power generation amount of the cascade is realized, the saving and utilization of water resources are indirectly reflected, and meanwhile, the scheduling of the cascade hydropower combined scheduling mode is facilitated, so that the optimal scheduling development of the cascade hydropower is promoted to a certain extent.
Drawings
FIG. 1 is a solution flow chart of the present invention;
FIG. 2 is a flow chart of the POA algorithm;
FIG. 3 is a graph showing the relationship between hydropower station water level and reservoir capacity, flow rate, head and output;
FIG. 4 is a flow chart of the original out and in warehouse of the cascade hydropower station;
FIG. 5 is a graph comparing an optimized dispatch line of a cascade hydropower station with an original dispatch line;
FIG. 6 is a graph of water storage flow distribution before and after optimization of a cascade hydropower station;
FIG. 7 is a graph of supplemental output distribution before and after optimization of a cascade hydropower station;
FIG. 8 is a graph of post-cascade hydropower station optimization power.
Detailed Description
The technical scheme of the invention is further described below by means of examples in combination with the accompanying drawings. The examples are only for more clearly illustrating the technical scheme of the present invention, and are not intended to limit the scope of the present invention.
And (3) a warehouse-in flow process, a warehouse-out flow process and starting and ending water levels of the reservoir of the cascade hydropower station in a given scheduling period. Under the condition of considering various constraint conditions, the storage and release process of each hydropower station of the step is determined, and the maximization of the non-storage capacity of the step power station is realized.
As shown in fig. 1, a cascade hydropower station joint scheduling method based on maximization of non-stored electric energy comprises the following steps:
s1, constructing a target scheduling function meeting various constraint conditions by taking the maximum utilization of the non-water storage capacity of the cascade hydropower station as a direction.
The expression of the objective function of maximizing the electric energy without accumulating is as follows:
wherein: e (E) Not store it The method comprises the steps of storing no electric energy for the t period of an ith hydropower station; n is the number of cascade hydropower stations; t is the number of scheduling period time periods; f (f) i The power coefficient of the ith hydropower station; h it An average power generation water head of the ith period of the ith hydropower station; q (Q) Not store it The method comprises the steps of (1) setting the total accumulation flow of the ith period of the ith hydropower station; Δt is the interval of the period.
Furthermore, the non-electricity storage energy optimization scheduling model of the cascade hydropower station meets cascade hydropower constraint and grid constraint, and the specific contents are as follows:
1) Equation of water balance
V i,t+1 ＝V it +(Q rit -Q cit )Δt
Wherein V is it 、V i,t+1 The initial and final reservoir capacities of reservoirs in the ith period of the ith hydropower station are respectively; q (Q) rit The method comprises the steps of (1) setting the warehouse-in flow of an ith hydropower station in an ith period; q (Q) cit The method comprises the steps of (1) setting the delivery flow of an ith hydropower station in an ith period; Δt (delta t)Is a time interval.
2) Reservoir level constraint
Z it,min ≤Z it ≤Z it,max
Wherein Z is it The water level of the ith period of the ith hydropower station; z is Z it,min The lowest water level which is allowed to fall in the t period of the ith hydropower station is the dead water level when no special requirement exists; z is Z it,max And when no special requirement exists, the flood season is generally flood control limit water level, and the non-flood season is normal water storage level.
3) Delivery flow constraints
Q cit,min ≤Q cit ≤Q cit,max
In which Q cit The method comprises the steps of (1) setting the delivery flow of an ith hydropower station in an ith period; q (Q) cit,min The minimum delivery flow which is ensured for the ith period of the ith hydropower station; q (Q) cit,max Maximum ex-warehouse flow allowed for the ith period of the ith hydropower station.
4) Hydraulic link constraint
Q r,i+1,t ＝q i+1,t +Q c,i,t-τi
In which Q r,i+1,t The warehousing flow rate of the (i+1) th hydropower station in the (t) th period; q i+1,t Interval flow of the (t) period of the (i+1) th hydropower station; q (Q) c,i,t The method comprises the steps of (1) setting the delivery flow of an ith hydropower station in an ith period; τ i The water flow lag time between the ith hydropower station and the (i+1) th hydropower station.
5) Power station output constraint
N it,min ≤N it ≤N it,max
Wherein N is it Generating power for the ith period of the ith hydropower station; n (N) it,min An upper output limit of a t period of the ith hydropower station; n (N) it,max The lower limit of the allowable output for the t period of the ith hydropower station.
6) Ex-warehouse flow equation
Q cit ＝Q fit +Q qit
In which Q cit The method comprises the steps of (1) setting the delivery flow of an ith hydropower station in an ith period; q (Q) fit Generating flow for the ith period of the ith hydropower station; q (Q) qit The water discharge quantity is the water discharge quantity of the ith period of the ith hydropower station.
7) Power station output lifting constraint
|N i,t+1 -N it |≤ΔN i
Wherein N is it 、N i,t+1 The output of the ith hydropower station at the beginning and the last period of the ith period is respectively; ΔN i And limiting the maximum output lifting of the ith hydropower station in a single period.
8) Equation of electric power balance
Wherein N is it The output of the ith period of time of the ith hydropower station; n is the number of cascade hydropower stations; p (P) t And the total output requirement of the step power station for the power grid in the t-th period is met.
S2, analyzing an objective function based on cascade hydropower station joint scheduling.
The difference of reservoir water accumulation and discharge layer depth can influence the power generation water head in the subsequent period, so that the influence on the non-electric storage energy of the cascade hydropower station can be generated. Differential analysis is carried out on the objective function of the non-electric storage energy:
wherein d ΣE Not store it The method is characterized in that the non-electric storage energy variation of the cascade hydropower station in a dispatching period is obtained; dH (dH) it The reservoir storage depth of the ith period of the ith hydropower station; w (W) Not store it Is the no water storage capacity of the ith period of the ith hydropower station.
Further, the objective function is analyzed during the water supply:
in the water supply process, the reservoir has a water-level-fluctuating trend, the power generation water head is reduced in a following way, and d sigma E Not store it Representing a cascade hydropower station within a dispatch periodThe smaller the loss of the non-stored electric energy, the larger the non-stored electric energy obtained by the cascade hydropower station.
The system demand load is provided by the non-accumulation force and the water-discharge supplementary force of the cascade power station together, and the balance equation is as follows:
wherein N is Library it Supplementing the output for the water discharge of the ith period of the ith hydropower station; n (N) Not store it A non-accumulating force for the ith period of the ith hydropower station; n (N) Is jt The method comprises the steps of setting the required load of a jth period of a jth power grid system; n is the number of cascade hydropower stations; and n is the number of power grid systems accessed by the cascade hydropower station.
The water discharge supplementary output is commonly born by all hydropower stations in the cascade hydropower stations, and the flow generated by the water discharge supplementary output of all the power stations is as follows:
further, the reservoir storage depth dH of the t period is obtained it ：
In which Q Library it Supplementing flow for the water discharged in the t period of the ith hydropower station; s is S Library it An average pool area for a nth time period of an ith hydropower station; h it Generating water head for the t period of the ith hydropower station; dV (dV) it The reservoir capacity variation of the ith hydropower station in the ith period is the reservoir capacity variation of the ith period; dH (dH) it The reservoir storage depth of the ith period of the ith hydropower station.
In the whole cascade hydropower station, except that the non-water storage capacity of the upstream first reservoir is determined by water supply, the non-water storage capacity of the rest reservoirs after the t-th period is composed of three parts, namely: the water storage capacity after the t period of the first reservoir, the water quantity stored in the secondary reservoir after the t period of the upstream reservoir and the water storage capacity after the t period of the two hydropower stations are not stored.
The functional expression of the water storage capacity of the cascade reservoir is as follows:
in which W is Not store it No water storage capacity for the ith period of the ith hydropower station; w (W) Not store 1t No water storage capacity for the t period of the 1 st hydropower station; w (W) Non-accumulating yt No water storage is generated for the interval of the t period of the y-th hydropower station; v (V) yt The water quantity stored in the storage capacity is developed after the nth period of the y-th hydropower station.
Substituting the formulas (5) and (6) into the formula (2) to obtain a cascade hydropower station water discharge supplementing output distribution function:
by reasonably distributing the complementary output N of each hydropower station of the cascade Library it Let d sigma E Not store it And obtaining the minimum value so that the loss of the step hydropower station for not storing electric energy is minimum, and the electric energy generated by the equivalent water is maximum, thereby realizing the maximum total power generation of the step hydropower station combined operation.
Further, the objective function is analyzed during impoundment:
in the water storage process, the reservoir is in an ascending trend, the power generation water head is raised along with the water storage process, and d sigma E is adopted Not store it The increment of the non-stored electric energy of the cascade hydropower station in the dispatching period is represented, and the larger the increment is, the larger the non-stored electric energy obtained by the cascade hydropower station is.
The system demand load is provided by the non-accumulating force of the cascade power station, and the equation is as follows:
wherein N is Not store it A non-accumulating force for the ith period of the ith hydropower station; n (N) Is jt The demand load of the jth period of the jth power grid system.
The hydropower stations in the cascade hydropower stations store water in a combined mode, and the water storage flow of each hydropower station is as follows:
further, the reservoir storage depth dH of the t period is obtained it ：
In which Q Storage it The water storage flow of the ith period of the ith hydropower station; s is S Library it An average pool area for a nth time period of an ith hydropower station; dV (dV) it The reservoir capacity variation of the ith hydropower station in the ith period is the reservoir capacity variation of the ith period; dH (dH) it The reservoir storage depth of the ith period of the ith hydropower station.
The balance equation of the water storage capacity of the cascade hydropower station is as follows, the water discarding condition in the water storage period is not considered, and the water discarding amount also belongs to a part of the water storage capacity of the hydropower station, so that the maximization of the electric energy without the water storage is not obvious in engineering significance.
Further, the functional expression of the water storage capacity in the t period is:
W storage of yt ＝Q Storage of yt Δt y∈i (12)
In which W is Not store it No water storage capacity for the ith period of the ith hydropower station; w (W) Warehouse-in 1t The water quantity is the warehouse entry water quantity of the 1 st hydropower station in the t period; w (W) Interval yt Water is supplied to the interval of the t period of the y-th hydropower station; w (W) Storage of yt Is the water storage capacity of the nth period of the nth hydropower station.
Substituting the formulas (10), (11) and (12) into the formula (2) to obtain the water storage distribution function of the cascade hydropower station:
water storage Q of each hydropower station through reasonable distribution steps Storage it Let d sigma E Not store it And the maximum value is obtained, so that the increment of the step hydropower station for not storing electric energy is maximum, the same electric energy is produced, and the water consumption is minimum, thereby realizing the maximum total power generation of the step hydropower station combined operation.
And S3, solving an objective function to obtain an optimized scheduling process of each power station in the cascade hydropower station.
The optimal solution for the complex function of the multi-stage multivariable is a work with huge calculation amount, and the solving method is also various, and the POA algorithm is adopted for solving. The POA algorithm (successive optimization algorithm) is a progressive optimality algorithm, and the theoretical basis is the inference of the optimality principle of bellman: the set of state variables for each period of the optimal trajectory is optimal relative to the set of neighboring state variables.
The solving step is shown in fig. 2, the objective function is decomposed into a plurality of two-stage optimization solutions, and after a plurality of iterative computations, the optimal solution of each two-stage is obtained, and finally the optimal solution of the objective function is obtained. The solving process is as follows:
step 1: an initial decision sequence is selected. As shown in fig. 3, the water level of the hydropower station is selected as a decision variable of the POA algorithm because the water level is indirectly or directly related to the reservoir capacity, the flow, the water head and the output. According to the water level constraint limit in the cascade reservoir scheduling period, the water level Z of each reservoir is limited it The discrete time interval is used as an initial dispatching line, and the discrete result is as follows:
step 2: two-stage optimizing. Fix Z 11 、Z 13 Adjust Z 12 So that the objective function is at Z 11 -Z 12 、Z 12 -Z 13 Obtaining optimal values for two periods of time by using Z at the moment 12 * Replacement of original Z 12 . Slide rightwards in turn to fix Z 12 *、Z 14 Adjust Z 13 Obtaining Z under the optimal solution 13 * . Finally fix Z NT-2 、Z NT Seeking the optimal water level Z NT-1 * 。
Step 3: and (5) iterative calculation. And (3) taking the water level optimization scheduling line obtained in the step (2) as an initial scheduling line, and repeating the step (2) by the same method to perform optimization.
Step 4: and (5) judging the precision. And (3) if the obtained optimized scheduling meets the precision requirement, the obtained result is the optimal scheduling line, otherwise, the step (2) and the step (3) are repeated until the requirement is met.
Examples
The step power station composed of the a power station and the B power station is described as an example, wherein the a power station is an upstream water power station, and the B power station is a downstream water power station. The river channel propagation time between the A power station and the B power station is about 2 hours, and no large branch flows are gathered in the middle, so that the ex-warehouse flow of the A power station can be approximately considered to be equal to the in-warehouse flow of the B power station. As shown in fig. 4, study data were obtained from day 1 to day 30 of 12 months.
By adopting the method, the dispatching process of the cascade power stations is optimized, the dispatching process line of the pool water level after optimizing the cascade hydropower stations is shown as a figure 5, and as can be seen from the figure, the pool water level dispatching line of the A power station is unchanged from the original pool water level, the pool water level is improved and then falls down by reasonably distributing water storage and output, the overall water level is controlled to be higher, the power generation water head in the dispatching period is improved, thus higher power generation efficiency and more power generation capacity are obtained, the pool water level in the dispatching period after optimizing the lower-level B power station is not higher, and the compensation and adjustment effects on the A power station are mainly played. The optimized water storage flow distribution and the supplementary output distribution of each hydropower station are respectively shown in fig. 6 and 7, the water storage flow of the power station A is in a trend of ascending and descending, the supplementary output is in a trend of descending and ascending, and the distribution of the water supply condition is combined, so that after the reservoir water level is lifted to a certain height in the early stage, the power generation flow and the water supply flow of the power station are basically in a state of balanced storage and discharge by mainly distributing the water storage flow and the supplementary output in the middle stage, so that the high water level and the high water head operation are maintained, and the non-storage flow obtains larger power generation efficiency; in the later scheduling period, in order to ensure that the cascade power station reaches the control target of electric quantity or water level, the supplementary output is increased, the water storage flow distribution is obviously reduced, and the average utilization water head is obviously improved in the whole scheduling period after optimization. The B power station belongs to the next-stage power station, and mainly plays a role in supplementing and adjusting the upper-stage power station, the water storage flow is in a trend of middle high and low ends, and the supplementing output is in a trend of middle low and high ends. In the early scheduling stage, the water storage flow of the power station A is distributed more, so that the output and the discharging flow are lower, and in order to meet all constraint limiting conditions, the power station B mainly supplements the output distribution in the early scheduling stage; in the middle scheduling period, the output and the downward leakage flow of the power station A are increased, and the power station B is mainly distributed by the water storage flow so as to raise the water level of a warehouse and raise the power generation water head; in the later stage of scheduling, in order to ensure that the cascade power station reaches the control target of electric quantity or water level, the B power station also takes the increase of the supplementary output distribution as the main part. The total power generation amount and the non-power storage amount of each hydropower station after the optimization of the steps are shown in fig. 8.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The foregoing embodiments are merely preferred embodiments of the present invention, and should not be construed as limiting the present invention, and the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without collision. The protection scope of the present invention is defined by the claims, and the protection scope includes equivalent alternatives to the technical features of the claims. I.e., equivalent replacement modifications within the scope of this invention are also within the scope of the invention.
Claims (8)
1. A cascade hydropower station joint scheduling method based on maximization of non-stored electric energy is characterized by comprising the following steps of: it comprises the following steps:
s1, constructing a target scheduling function meeting various constraint conditions by taking the maximum utilization of the water storage capacity of the cascade hydropower station as a direction;
s2, analyzing an objective function based on cascade hydropower station joint scheduling;
s3, solving an objective function to obtain an optimized scheduling process of each power station in the cascade hydropower station;
in S2, differential analysis is performed on the objective function as follows:
（2）
in the method, in the process of the invention,the method is characterized in that the non-electric storage energy variation of the cascade hydropower station in a dispatching period is obtained; />Is->Hydropower station No>Reservoir storage depth of each period; />Is->Hydropower station No>No water storage capacity for each period;
in the water supply process, the reservoir has a water-level-fluctuating trend, the power generation water head is reduced along with the water supply,representing the loss of the step hydropower station in the electric energy not stored in the dispatching period, wherein the smaller the loss is, the larger the electric energy not stored in the step hydropower station is;
1) The system demand load is provided by the non-accumulation force and the water-discharge supplementary force of the cascade power station together, and the balance equation is as follows:
（3）
in the method, in the process of the invention,is->Hydropower station No>The water discharge of each period supplements the output; />Is->Hydropower station No>A non-accumulating force for each period; />Is->Personal electric network system->Demand load for each time period;Nthe number of the cascade hydropower stations is the number; />The number of power grid systems connected to the cascade hydropower station;
2) The water discharge supplementary output is commonly born by all hydropower stations in the cascade hydropower stations, and the flow generated by the water discharge supplementary output of all the power stations is as follows:
（4）
further, obtainTime period reservoir storage depth->：
（5）
In the method, in the process of the invention,is->Hydropower station No>The water discharge supplementing flow rate of each period; />Is->Hydropower station No>Average library area for each time period; />Is->Hydropower station No>Generating water heads of different time periods; />Is->Hydropower station No>Reservoir capacity variation in each period; />Is->Hydropower station No>Reservoir storage depth of each period;
3) In the whole cascade hydropower station, except that the non-water storage capacity of the upstream first reservoir is determined by the water supply, the rest reservoirs are the firstThe non-water storage after each period consists of three parts, namely: first reservoir->No water storage after a certain period of time, upstream reservoir->The water quantity stored in the Xingliku capacity after a certain period of time and the two hydropower stations are +.>The water storage capacity is not generated after each period, and the function expression of the water storage capacity is:
（6）
in the method, in the process of the invention,is->Hydropower station No>No water storage capacity for each period; />For the 1 st hydropower station->No water storage capacity for each period; />Is->Hydropower station No>The interval of each period does not store water; />Is->Hydropower station No>The amount of water stored in the reservoir volume is increased after each period of time.
2. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy according to claim 1, wherein the method comprises the following steps: in the step S1, the objective function expression is:
（1）
wherein:is->Hydropower station No>The electric energy is not stored in each period;Nthe number of the cascade hydropower stations is the number;Tthe number of time periods is the scheduling period; />Is->The power output coefficients of the hydropower stations; />Is->Hydropower station No>Average power generation head of each period; />Is->Hydropower station No>The non-accumulated flow of each period; />Is a time interval.
3. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy according to claim 2, wherein the method comprises the following steps: constraints of the objective function include: the method comprises the following steps of water balance equation, reservoir water level constraint, ex-warehouse flow constraint, hydraulic connection constraint, power station output constraint, ex-warehouse flow equation, power station output lifting constraint and electric power balance equation.
4. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy according to claim 1, wherein the method comprises the following steps: substituting the formulas (5) and (6) into the formula (2), wherein the water supply process cascade hydropower station water discharge supplementing output distribution function is as follows:
（7）
by reasonably distributing the supplementary output of each hydropower station of the cascadeMake->And obtaining the minimum value so that the loss of the step hydropower station for not storing electric energy is minimum, and the electric energy generated by the equivalent water is maximum, thereby realizing the maximum total power generation of the step hydropower station combined operation.
5. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy according to claim 1, wherein the method comprises the following steps: in the water storage process, the reservoir is in an upward trend, the power generation water head is raised along with the water storage process,representing the increment of the step hydropower station which does not store electric energy in the dispatching period, wherein the larger the increment is, the larger the electric energy obtained by the step hydropower station is;
1) The system demand load is provided by the non-accumulating force of the cascade power station, and the equation is as follows:
（8）
in the method, in the process of the invention,is->Hydropower station No>A non-accumulating force for each period; />Is->Personal electric network system->Demand load for each time period;
2) The water storage of each hydropower station in the cascade hydropower station is combined, and the water storage flow of each hydropower station is as follows:
（9）
further, obtainTime period reservoir storage depth->：
（10）
In the method, in the process of the invention,is->Hydropower station No>Water storage flow in each time period; />Is->Hydropower station No>Average library area for each time period; />Is->Hydropower station No>Reservoir capacity variation in each period; />Is->Hydropower station No>Reservoir storage depth of each period;
3) The equilibrium equation of the water storage capacity of the cascade hydropower station in the water storage process is as follows:
（11）
further, the method comprises the steps of,the time period water storage capacity has a function expression as follows:
（12）
in the method, in the process of the invention,is->Hydropower station No>No water storage capacity for each period; />For the 1 st hydropower station->The water quantity in storage in each period; />Is->Hydropower station No>Water inflow in intervals of a plurality of time periods; />Is->Hydropower station No>Water storage capacity for each time period; q (Q) Storage of yt For the y-th hydropower station->Water storage flow in each time period.
6. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy, which is disclosed by claim 5, is characterized in that: substituting formulas (10), (11) and (12) into formula (2), wherein the water storage distribution function of the cascade hydropower station in the water storage process is as follows:
（13）
by reasonably distributing the water storage capacity of each hydropower station of the cascadeMake->And the maximum value is obtained, so that the increment of the step hydropower station for not storing electric energy is maximum, the same electric energy is produced, and the water consumption is minimum, thereby realizing the maximum total power generation of the step hydropower station combined operation.
7. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy according to claim 1, wherein the method comprises the following steps: in the step S3, the POA algorithm is utilized to solve, the objective function is decomposed into a plurality of two-stage optimization solutions, and the optimal solution meeting the requirements is obtained after a plurality of iterative computations.
8. The cascade hydropower station joint scheduling method based on the maximization of the stored electric energy, which is disclosed by claim 7, is characterized in that: the step S3 is specifically as follows: decomposing the multi-stage optimization problem into a plurality of two-stage optimization problems, optimizing all the two stages one by one, and finally obtaining an optimal solution meeting the precision requirement after multiple iterations, wherein the solving process comprises four steps: selecting an initial decision sequence, and establishing an initial scheduling line by taking the water level of a hydropower station reservoir as an initial sequence; two-stage optimizing; iterative calculation; and (5) judging the precision.
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