CN104635769A - Method for controlling optimal hydropower station flood period water level range of cascaded hydropower stations - Google Patents

Abstract

The invention discloses a method for controlling an optimal hydropower station flood period water level range of cascaded hydropower stations. The method comprises the following steps: firstly, giving a reservoir inflow frequency curve and an expected water abandoning probability of each cascade of hydropower station in advance and then sequentially carrying out calculation on the hydropower stations reservoir by reservoir according to a sequence from upstream to downstream; if one hydropower station has performance above seasonal regulation, respectively calculating the optimal water levels of first-cascade and non-first-cascade hydropower stations and calculating a total storage outflow expectation of the hydropower station; if the hydropower station does not have performance above seasonal regulation, calculating storage outflow of the hydropower station by utilizing a water balance equation and sequentially traversing all the hydropower stations to obtain the optimal water level range of all the hydropower stations with performance above seasonal regulation in the hydropower stations at a certain moment. According to the method, a real-time water storage and discharge strategy of the cascaded hydropower stations can be scientifically guided, the water abandoning probability of each cascade of hydraulic power plant is guaranteed to be in a controllable range, the water abandoning probability of the cascaded hydropower stations is reduced and loss caused by flood and waterlogging in a drainage basin is reduced.

Description

A kind of Hydropower Stations power station optimum water level range control method in flood season

Technical field

The present invention relates to a kind of Hydropower Stations power station optimum water level range control method in flood season, belong to water conservancy and hydropower control technology field.

Background technology

Hydropower station at present all adopts flood season limit level to limit reservoir level flood season, but the degree of safety in fact owing to getting in hydroelectric station design is different, or because new power plant construction changes River Basin Hydrology characteristic, when step each power station reservoir level will be made to be in flood season limit level equally, there is very large difference in the probability abandoning water, larger to the defensive ability/resistance ability difference of flood.This mode effectively cannot control in the rational optimum water level range in power station according to the water probability of abandoning in real time in power station, while causing Hydropower Stations entirety to abandon the increase of water probability, reduces the waterpower utilization rate in flood season.

Summary of the invention

In order to address the deficiencies of the prior art, the invention provides a kind of Hydropower Stations power station optimum water level range control method in flood season, what utilization had been drafted rationally abandons water risk control standard, by the period anti-the highest permission water level pushing away each power station, and then obtain the optimum water level range in flood season in each power station, combining for GROUP OF HYDROPOWER STATIONS Optimized Operation of avoiding the peak hour provides foundation.

For achieving the above object, the technical solution used in the present invention is as follows:

A kind of Hydropower Stations power station optimum water level range control method in flood season, comprises the following steps:

1) water risk is abandoned in the reservoir inflow frequency curve in power station at different levels given in advance and expection;

2) successively power station is calculated according to the order being from upstream to downstream;

3) if this power station possesses regulate above performance season, be then judged as that chopped-off head power station is also non-chopped-off head power station, if chopped-off head power station then proceeds to step 4); If be non-chopped-off head power station, proceed to step 5); If this power station does not possess regulate above performance season, then proceed to step 6);

4) calculate the optimum water level in this chopped-off head power station and total storage outflow expectation value in this chopped-off head power station, then proceed to step 7);

5) calculate total storage outflow expectation value in this non-chopped-off head power station and the optimum water level in this non-chopped-off head power station, then proceed to step 7);

6) utilize water balance equation to extrapolate the storage outflow in this power station, then proceed to step 7);

7) judge whether to have traveled through all power stations, if so, then terminate, if not, then proceed to step 3).

The scheduling rule in aforesaid chopped-off head power station and non-chopped-off head power station is: when power station does not reach flood season limit level, pay the utmost attention to retaining, arrive after flood season limit level until power station, under utilizing unit to follow the tracks of, let out reservoir inflow, when reservoir inflow exceed unit completely send out flow time, power station opens a sluice gate to abandon water.

Aforesaid step 4) in the defining method of optimum water level in chopped-off head power station be:

First in reservoir inflow frequency curve, a certain swallowing-capacity I ' is found ₁, make reservoir inflow I ₁be greater than this swallowing-capacity I ' ₁probability just in time for chopped-off head power station expection abandon water risk P ₁: P (I ₁> I ' ₁)=P ₁;

According to water balance formula, obtain the expection of this chopped-off head power station and abandon water risk P ₁corresponding optimum storage capacity V ₁':

V ₁′＝V _1,l-(I ₁′-Q _1,gen)Δt (2)

Wherein, Q _{1, gen}for chopped-off head Hydropower Plant completely sends out flow, V _{1, l}for the corresponding storage capacity of chopped-off head power station flood season limit level, V ₁' for chopped-off head power station expection abandon water risk P ₁corresponding optimum storage capacity;

Again according to water level-capacity property curve, check in the optimum storage capacity V in this chopped-off head power station ₁the water level Z ' of ' correspondence ₁, be this expection and abandon water risk P ₁corresponding optimum reservoir level.

Aforesaid step 4) in the computing method of total storage outflow expectation value in chopped-off head power station be:

The total storage outflow Q in the above power station of chopped-off head season adjusting function ₁be expressed as:

$Q_1=\left\{\begin{array}{cc}{I}_1-(V_{1,l}-V_1^{\text{'}})/\mathrm{\&Delta;t},& I_1>(V_{1,l}-V_1^{\text{'}})/\mathrm{\&Delta;t}\\ 0,& 0\&le;I_1\&le;(V_{1,l}-V_1^{\text{'}})/\mathrm{\&Delta;t},V_1^{\text{'}}<V_{1,l}\end{array}\right.---\left(3\right)$

Definition Q "=(V _{1, l}-V ₁')/Δ t,

Then formula (3) is deformed into: $Q_1=\left\{\begin{array}{cc}{I}_1-Q^{\text{'}\text{'}},& I_1>Q^{\text{'}\text{'}}\\ 0,& 0\&le;I_1\&le;Q^{\text{'}\text{'}},Q^{\text{'}\text{'}}>0\end{array}\right.$

The then above power station of chopped-off head season adjusting function total storage outflow expectation value E (Q ₁) be:

$E\left(Q_1\right)=\underset{Q^{\text{'}\text{'}}}{\overset{\&infin;}{\&Integral;}}{I}_1\&CenterDot;f\left(I_1\right)\&CenterDot;d{I}_1-Q^{\text{'}\text{'}}\&CenterDot;\underset{Q^{\text{'}\text{'}}}{\overset{\&infin;}{\&Integral;}}f\left(I_1\right)\&CenterDot;d{I}_1---\left(4\right)$

Wherein, f (I ₁) be the probability density function of this power station reservoir inflow, meet:

In formula, the gamma function that Γ (α) is α, α, β, α ₀for three parameters of P-III type curve.

Aforesaid step 5) in the computing method of total storage outflow expectation value in non-chopped-off head power station be:

The total storage outflow in the above power station of non-chopped-off head season adjusting function is expressed as:

$Q_i=\left\{\begin{array}{cc}{\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}}+I_i-(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t},& I_i>(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t}\\ 0,& 0\&le;I_i\&le;(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t},V_i^{\text{'}}<V_{i,l}\end{array}\right.---\left(5\right)$

Wherein, Q _ibe total storage outflow in i-th grade of above power station of non-chopped-off head season adjusting function, for total storage outflow expectation value in the upper water power station in i-th grade that has calculated non-chopped-off head power station, V ' _ibe that water risk P is abandoned in i-th grade of non-chopped-off head power station expection _icorresponding optimum storage capacity, I _ibe the interval reservoir inflow in i-th grade of non-chopped-off head power station, V _i,lbe i-th grade of corresponding storage capacity of non-chopped-off head power station flood season limit level;

Definition $I^{\text{'}\text{'}}=(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t}-{\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}},$

$Q_i=\left\{\begin{array}{cc}{I}_i-I^{\text{'}\text{'}},& I_i>I^{\text{'}\text{'}}\\ 0,& 0\&le;I_i\&le;I^{\text{'}\text{'}},I^{\text{'}\text{'}}>0\end{array}\right.$

Then formula (5) is deformed into:

The then i-th grade of above power station of non-chopped-off head season adjusting function total storage outflow expectation value E (Q _i) be:

$E\left(Q_i\right)=\underset{I^{\text{'}\text{'}}}{\overset{\&infin;}{\&Integral;}}{I}_i\&CenterDot;f\left(I_i\right)\&CenterDot;d{I}_i-I^{\text{'}\text{'}}\&CenterDot;\underset{I^{\text{'}\text{'}}}{\overset{\&infin;}{\&Integral;}}f\left(I_i\right)\&CenterDot;d{I}_i---\left(6\right)$

Wherein, f (I _i) be the probability density function of this i-th grade interval reservoir inflow in the above power station of non-chopped-off head season adjusting function.

Aforesaid step 5) in the defining method abandoning water risk in non-chopped-off head power station be:

First in interval reservoir inflow frequency curve, a certain swallowing-capacity I ' is found _i, make interval reservoir inflow I _ibe greater than this swallowing-capacity I ' _iprobability just in time for water risk P is abandoned in this non-chopped-off head power station expection _i: P (I _i> I ' _i)=P _i

According to principle of water balance, obtain i-th grade of non-chopped-off head power station expection and abandon water risk P _icorresponding optimum storage capacity V ' _i:

$V_i^{\text{'}}=V_{i,l}-({\stackrel{\&OverBar;}{Q}}_{i,\mathrm{perv}}+V_i^{\text{'}}-Q_{i,\mathrm{gen}})\mathrm{\&Delta;t}---\left(9\right)$

Wherein, be the expectation value of total storage outflow in upper water power station, i-th grade of non-chopped-off head power station, Q _{i, gen}i-th grade of non-chopped-off head Hydropower Plant completely sends out flow;

Again according to the water level-capacity property curve in this grade of power station, check in i-th grade of optimum storage capacity V ' in non-chopped-off head power station _icorresponding water level Z ' _i, be the expection of this power station and abandon water risk P _icorresponding optimum reservoir level.

Aforesaid step 6) in do not possess the power station regulating above performance season storage outflow Q be: wherein, I is the average area reservoir inflow value over the years in this grade of power station this month, for the expectation value of total storage outflow in upper water power station.

By adopting above-mentioned technological means, the beneficial effect that the present invention has is:

Compared with prior art, the present invention considers the rule characteristic of Hydropower Stations interval inflow, power station characteristic, real-time running state, the information such as waterpower impact between adjacent power station, can accept maximumly to abandon water probability based on given expection, the real-time each power station of calculating step the highest corresponding controlling water level, formed respectively with the highest controlling water level, level of dead water is the optimum water lev el control scope in flood season of bound, can scientific guidance Hydropower Stations store the strategy that discharges water in real time, that guarantees each hydroelectric power plant of step abandons water probability in controlled range, reduce the probability that Hydropower Stations abandons water, reduce basin losses due to flood and waterlogging.

Accompanying drawing explanation

Fig. 1 is Hydropower Stations power station of the present invention optimum water level range control method in flood season process flow diagram.

Embodiment

Now with embodiment, the present invention is described in further detail by reference to the accompanying drawings.

As shown in Figure 1, Hydropower Stations power station optimum water level range control procedure in flood season is as follows: water risk is abandoned in reservoir inflow frequency curve and the expection in power station at different levels first given in advance, then according to the order from downstream, upstream to calculating power station successively: if power station possesses regulate above performance season, then its optimum water level is calculated respectively to chopped-off head and non-chopped-off head power station and calculates the total storage outflow in this power station and expect; If this power station does not possess regulate above performance season, then water balance equation is only utilized to extrapolate the storage outflow in this power station.Travel through all power stations successively, the optimum water level range in the above power station of a certain moment GROUP OF HYDROPOWER STATIONS all seasons adjusting function can have been obtained.

The optimum reservoir level Z ' in all power stations _i, i=1,2 ..., N forms one and characterizes the vector optimizing reservoir level combination.By this superior vector value, dispatcher can judge the optimizing regulation strategy in power station at different levels, and by the reasonable utilization of genset and floodgate, all power stations are regulated simultaneously, so that the entirety effectively controlling GROUP OF HYDROPOWER STATIONS abandons water risk towards this vector direction.When the most desirable (error free), regulate power station should reach Z ' at the reservoir level in the scheduling end of term in all seasons simultaneously _i, i=1,2 ..., N.

Need in the inventive method to calculate the optimum water level in chopped-off head and non-chopped-off head power station and respective total storage outflow expectation, detailed process is as follows:

One, chopped-off head power station optimum water level range defining method in flood season

Can accept the prerequisite of maximum risk value in given expection under, reservoir level should be raised as much as possible in power station, to be conducive to later stage generating and emerging profit.Therefore, when determining optimum water level range, only need to calculate reservoir level corresponding to expection maximum risk value, this reservoir level is the upper limit of optimum water lev el control scope, should in conjunction with later stage possibility water situation and Interpretation Method of Area Rainfall error condition in practical operation, by actual library water lev el control under this optimum reservoir level, and reserved certain margin of safety.

Thus, the optimum water lev el control range problem in chopped-off head power station can be converted into: the natural reservoir inflow frequency curve of known chopped-off head power station current residing period, and power station is at [t ₀, t ₀+ Δ t] expect in the period and abandon water risk P ₁prerequisite under, instead push away current time t ₀optimum reservoir level Z ' ₁.

First, in natural reservoir inflow frequency curve, a certain swallowing-capacity I ' is found ₁, make reservoir inflow I ₁be greater than this swallowing-capacity I ' ₁probability just in time for water risk P is abandoned in the expection in this power station ₁.

P(I ₁＞I′ ₁)＝P ₁

This swallowing-capacity I ' ₁while Hydropower Plant should be made completely to send out, from current storage capacity water level Z _1,0retaining is to flood season limit level Z _{1, l}.

As reservoir inflow I ₁be greater than this swallowing-capacity I ' ₁time, water is abandoned in power station; As reservoir inflow I ₁be less than this swallowing-capacity I ' ₁time, water is not abandoned in power station.

According to water balance formula, can obtain:

V ₁′+(I′ ₁-Q _1,gen)Δt＝V _1,l(1)

That is:

V ₁′＝V _1,l-(I′ ₁-Q _1,gen)Δt (2)

Wherein, Q _{1, gen}for chopped-off head Hydropower Plant completely sends out flow, V _{1, l}for the corresponding storage capacity of chopped-off head power station flood season limit level, the corresponding storage capacity V of Limited Water Level of Reservoir in Flood Season _{1, l}flow Q is completely sent out with unit _{1, gen}can obtain from the design data in power station, V ₁' for chopped-off head power station expection abandon water risk P ₁corresponding optimum storage capacity.

Again according to the water level-capacity property curve in power station, check in optimum storage capacity V ₁the water level Z ' of ' correspondence ₁, be this expection and abandon water risk P ₁corresponding optimum reservoir level.

Two, non-chopped-off head power station optimum water level range defining method in flood season

When determining the optimum water level in non-chopped-off head power station, need the storage outflow situation considering higher level power station.For the power station below season adjusting function, interval reservoir inflow adopts average runoff, directly calculates storage outflow according to the principle going out warehouse-in balance; For power station more than season adjusting function, interval reservoir inflow is the stochastic variable of obeying P-III type, utilizes principle of water balance and random variable expected value computing formula, calculates the storage outflow expectation value in power station.

(1) the total storage outflow expectation value in the above power station of chopped-off head season adjusting function calculates

Assuming that the scheduling rule in power station is: when power station does not reach flood season limit level, pay the utmost attention to retaining, arrive after flood season limit level until power station, under utilizing unit to follow the tracks of, let out reservoir inflow, when reservoir inflow exceed unit completely send out flow time, power station opens a sluice gate to abandon water.

Total storage outflow Q in chopped-off head power station ₁reservoir inflow I ₁function, and reservoir inflow is a stochastic variable.Thus, power station storage outflow is also a stochastic variable, codomain be [0, ∞).

$Q_1=\left\{\begin{array}{cc}{I}_1-(V_{1,l}-V_1^{\text{'}})/\mathrm{\&Delta;t},& I_1>(V_{1,l}-V_1^{\text{'}})/\mathrm{\&Delta;t}\\ 0,& 0\&le;I_1\&le;(V_{1,l}-V_1^{\text{'}})/\mathrm{\&Delta;t},V_1^{\text{'}}<V_{1,l}\end{array}\right.---\left(3\right)$

Note Q "=(V _{1, l}-V ₁')/Δ t,

Then $Q_1=\left\{\begin{array}{cc}{I}_1-Q^{\text{'}\text{'}},& I_1>Q^{\text{'}\text{'}}\\ 0,& 0\&le;I_1\&le;Q^{\text{'}\text{'}},Q^{\text{'}\text{'}}>0\end{array}\right.$

By the mathematical expectation formula of function of random variable can obtain:

Chopped-off head power station total storage outflow expectation value E (Q ₁) be:

$E\left(Q_1\right)=\underset{0}{\overset{Q^{\&prime;\&prime;}}{\&Integral;}}0\&CenterDot;f\left(I_1\right)\&CenterDot;{\mathrm{dI}}_1+\underset{Q^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}(I_1-Q^{\&prime;\&prime;})\&CenterDot;f\left(I_1\right)\&CenterDot;{\mathrm{dI}}_1=\underset{Q^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}{I}_1\&CenterDot;f\left(I_1\right)\&CenterDot;{\mathrm{dI}}_1-Q^{\&prime;\&prime;}\&CenterDot;\underset{Q^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}f\left(I_1\right)\&CenterDot;{\mathrm{dI}}_1---\left(4\right)$

Wherein, f (I ₁) obey the probability density function of P-III type curve distribution:

$f\left(I_1\right)=\frac{{\mathrm{\&beta;}}^{\mathrm{\&alpha;}}}{\mathrm{\&Gamma;}\left(\mathrm{\&alpha;}\right)}{(I_1-{\mathrm{\&alpha;}}_0)}^{\mathrm{\&alpha;}-1}{e}^{-\mathrm{\&beta;}(I_1-{\mathrm{\&alpha;}}_0)}$

In formula, the gamma function that Γ (α) is α; α, β, α ₀for three parameters of P-III type curve.

(2) the total storage outflow expectation value in the above power station of non-chopped-off head season adjusting function calculates

In optimum water level range calculates, non-chopped-off head season adjusting function above power station scheduling rule is identical with the above power station of chopped-off head season adjusting function, but is the waterdrainage amount that the above power station of non-chopped-off head season adjusting function needs to consider its upper water power station.The present invention supposes that each segment natural water flow is separate, under this definition, can adopt the mode by the total storage outflow of storehouse calculation expectation.Therefore, when the total storage outflow expectation value in the calculating above power station of each non-chopped-off head season adjusting function, the total storage outflow expectation value (fixed value) being superimposed with swimming power station in water balance equation is only needed.

Total storage outflow Q in the above power station of non-chopped-off head season adjusting function _imeet:

$Q_i=\left\{\begin{array}{cc}{\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}}+I_i-(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t},& I_i>(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t}\\ 0,& 0\&le;I_i\&le;(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t},V_i^{\text{'}}<V_{i,l}\end{array}\right.---\left(5\right)$

Wherein, Q _ibe total storage outflow in i-th grade of above power station of non-chopped-off head season adjusting function, for total storage outflow expectation value in the upper water power station in i-th grade that has calculated non-chopped-off head power station, V _i' be that water risk P is abandoned in i-th grade of non-chopped-off head power station expection _icorresponding optimum storage capacity, I _ibe the interval reservoir inflow in i-th grade of non-chopped-off head power station, V _i,lbe i-th grade of corresponding storage capacity of non-chopped-off head power station flood season limit level;

Note $I^{\text{'}\text{'}}=(V_{i,l}-V_i^{\text{'}})/\mathrm{\&Delta;t}-{\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}};$

Then $Q_i=\left\{\begin{array}{cc}{I}_i-I^{\text{'}\text{'}},& I_i>I^{\text{'}\text{'}}\\ 0,& 0\&le;I_i\&le;I^{\text{'}\text{'}},I^{\text{'}\text{'}}>0\end{array}\right.$

By the mathematical expectation formula of function of random variable can obtain:

I-th grade of non-chopped-off head power station total storage outflow expectation value E (Q _i) be:

$E\left(Q_i\right)=\underset{0}{\overset{I^{\&prime;\&prime;}}{\&Integral;}}0\&CenterDot;f\left(I_i\right)\&CenterDot;{\mathrm{dI}}_i+\underset{I^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}(I_i-I^{\&prime;\&prime;})\&CenterDot;f\left(I_i\right)\&CenterDot;{\mathrm{dI}}_i=\underset{I^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}{I}_i\&CenterDot;f\left(I_i\right)\&CenterDot;{\mathrm{dI}}_i-I^{\&prime;\&prime;}\&CenterDot;\underset{I^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}f\left(I_i\right)\&CenterDot;{\mathrm{dI}}_i---\left(6\right)$

Wherein, f (I _i) be the probability density function of the interval reservoir inflow in this power station,

$f\left(I_i\right)=\frac{{\mathrm{\&beta;}}^{\mathrm{\&alpha;}}}{\mathrm{\&Gamma;}\left(\mathrm{\&alpha;}\right)}{(I_i-{\mathrm{\&alpha;}}_0)}^{\mathrm{\&alpha;}-1}{e}^{-\mathrm{\&beta;}(I_i-{\mathrm{\&alpha;}}_0)}.$

(3) the total storage outflow expectation value in power station below season adjusting function calculates

For power station below season adjusting function, assuming that this power station maintains initial water level (being generally flood season limit level) all the time, do not consider that it retains effect to flood.In addition, using the average area reservoir inflow value over the years in this grade of power station this month as fixing regional water volume input, according to water balance formulae discovery storage outflow, namely wherein, I is the average area reservoir inflow value over the years in this grade of power station this month, for the expectation value of total storage outflow in upper water power station.

(4) non-chopped-off head power station optimum water level range in flood season calculates

First, in interval reservoir inflow frequency curve, a certain swallowing-capacity I ' is found _i, make interval reservoir inflow I _ibe greater than this swallowing-capacity I ' _iprobability just in time for water risk P is abandoned in expection _i,

P(I _i＞I′ _i)＝P _i(7)

Ignore current time lag between upstream and downstream power station and smoothly turn use into, obtaining according to principle of water balance:

$V_i^{;}+({\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}}+I_i^{\text{'}}-Q_{i,\mathrm{gen}})\mathrm{\&Delta;t}=V_{i,l}---\left(8\right)$

Wherein, be the expectation value of total storage outflow in upper water power station, i-th grade of non-chopped-off head power station, Q _{i, gen}i-th grade of non-chopped-off head Hydropower Plant completely sends out flow,

Formula (8) is deformed into:

$V_i^{\text{'}}=V_{i,l}-({\stackrel{\&OverBar;}{Q}}_{i,\mathrm{perv}}+I_i^{\text{'}}-Q_{i,\mathrm{gen}})\mathrm{\&Delta;t}---\left(9\right)$

Wherein, Q _{i, gen}and V _i,lall can obtain from hydroelectric station design data;

Again according to the water level-capacity property curve in this grade of power station, check in i-th grade of optimum storage capacity V in non-chopped-off head power station _ithe water level Z ' of ' correspondence _i, be the expection of this power station and abandon water risk P _icorresponding optimum reservoir level.

Claims (7)

1. a Hydropower Stations power station optimum water level range control method in flood season, is characterized in that: comprise the following steps:

1) water risk is abandoned in the reservoir inflow frequency curve in power station at different levels given in advance and expection;

2) successively power station is calculated according to the order being from upstream to downstream;

3) if this power station possesses regulate above performance season, be then judged as that chopped-off head power station is also non-chopped-off head power station, if chopped-off head power station then proceeds to step 4); If be non-chopped-off head power station, proceed to step 5); If this power station does not possess regulate above performance season, then proceed to step 6);

4) calculate the optimum water level in this chopped-off head power station and total storage outflow expectation value in this chopped-off head power station, then proceed to step 7);

5) calculate total storage outflow expectation value in this non-chopped-off head power station and the optimum water level in this non-chopped-off head power station, then proceed to step 7);

6) utilize water balance equation to extrapolate the storage outflow in this power station, then proceed to step 7);

7) judge whether to have traveled through all power stations, if so, then terminate, if not, then proceed to step 3).

2. a kind of Hydropower Stations power station according to claim 1 optimum water level range control method in flood season, it is characterized in that: the scheduling rule in described chopped-off head power station and non-chopped-off head power station is: when power station does not reach flood season limit level, pay the utmost attention to retaining, arrive after flood season limit level until power station, reservoir inflow is let out under utilizing unit to follow the tracks of, when reservoir inflow exceed unit completely send out flow time, power station opens a sluice gate to abandon water.

3. a kind of Hydropower Stations power station according to claim 1 flood season optimum water level range control method, it is characterized in that: described step 4) in the defining method of optimum water level in chopped-off head power station be:

First in reservoir inflow frequency curve, a certain swallowing-capacity I ' is found ₁, make reservoir inflow I ₁be greater than this swallowing-capacity I ' ₁probability just in time for chopped-off head power station expection abandon water risk P ₁: P (I ₁> I ' ₁)=P ₁;

According to water balance formula, obtain the expection of this chopped-off head power station and abandon water risk P ₁corresponding optimum storage capacity V ' ₁:

V′ ₁＝V _1,l-(I′ ₁-Q _1,gen)Δt (2)

Wherein, Q _{1, gen}for chopped-off head Hydropower Plant completely sends out flow, V _{1, l}for the corresponding storage capacity of chopped-off head power station flood season limit level, V ' ₁for water risk P is abandoned in the expection of chopped-off head power station ₁corresponding optimum storage capacity;

Again according to water level-capacity property curve, check in the optimum storage capacity V ' in this chopped-off head power station ₁corresponding water level Z ' ₁, be this expection and abandon water risk P ₁corresponding optimum reservoir level.

4. a kind of Hydropower Stations power station according to claim 1 flood season optimum water level range control method, it is characterized in that: described step 4) in the computing method of total storage outflow expectation value in chopped-off head power station be:

The total storage outflow Q in the above power station of chopped-off head season adjusting function ₁be expressed as:

$Q_1=\left\{\begin{array}{cc}{I}_1-(V_{1,l}-V_1^{\&prime;})/\mathrm{\&Delta;t},& I_1>(V_{1,l}-V_1^{\&prime;})/\mathrm{\&Delta;t}\\ 0,& 0\&le;I_1\&le;(V_{1,l}-V_1^{\&prime;})/\mathrm{\&Delta;t},V_1^{\&prime;}<V_{1,l}\end{array}\right.---\left(3\right)$

Definition Q "=(V _{1, l}-V ' ₁)/Δ t,

Then formula (3) is deformed into: $Q_1=\left\{\begin{array}{cc}{I}_1-Q^{\&prime;\&prime;},& I_1>Q^{\&prime;\&prime;}\\ 0,& 0\&le;I_1\&le;Q^{\&prime;\&prime;},Q^{\&prime;\&prime;}>0\end{array}\right.$

The then above power station of chopped-off head season adjusting function total storage outflow expectation value E (Q ₁) be:

$E\left(Q_1\right)=\underset{Q^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}{I}_1\&CenterDot;f\left(I_1\right)\&CenterDot;{\mathrm{dI}}_1-Q^{\&prime;\&prime;}\&CenterDot;\underset{Q^{\&prime;\&prime;}}{\overset{\&infin;}{\&Integral;}}f\left(I_1\right)\&CenterDot;{\mathrm{dI}}_1---\left(4\right)$

Wherein, f (I ₁) be the probability density function of this power station reservoir inflow, meet:

In formula, the gamma function that Γ (α) is α, α, β, α ₀for three parameters of P-III type curve.

5. a kind of Hydropower Stations power station according to claim 1 flood season optimum water level range control method, it is characterized in that: described step 5) in the computing method of total storage outflow expectation value in non-chopped-off head power station be:

The total storage outflow in the above power station of non-chopped-off head season adjusting function is expressed as:

$Q_i=\left\{\begin{array}{cc}{\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}}+I_i-(V_{i,l}-V_i^{\&prime;})/\mathrm{\&Delta;t},& I_i>(V_{i,l}-V_i^{\&prime;})/\mathrm{\&Delta;t}\\ 0,& 0\&le;I_i\&le;(V_{i,l}-V_i^{\&prime;})/\mathrm{\&Delta;t},V_i^{\&prime;}<V_{i,l}\end{array}\right.---\left(5\right)$

Wherein, Q _ibe total storage outflow in i-th grade of above power station of non-chopped-off head season adjusting function, for total storage outflow expectation value in the upper water power station in i-th grade that has calculated non-chopped-off head power station, V ' _ibe that water risk P is abandoned in i-th grade of non-chopped-off head power station expection _icorresponding optimum storage capacity, I _ibe the interval reservoir inflow in i-th grade of non-chopped-off head power station, V _i,lbe i-th grade of corresponding storage capacity of non-chopped-off head power station flood season limit level;

Definition $I^{\&prime;\&prime;}=(V_{i,l}-V_i^{\&prime;})/\mathrm{\&Delta;t}-{\stackrel{\&OverBar;}{Q}}_{i,\mathrm{prev}},$

Then formula (5) is deformed into: $Q_i=\left[\begin{array}{cc}{I}_i-I^{\&prime;\&prime;},& I_i>I^{\&prime;\&prime;}\\ 0,& 0\&le;I_i\&le;I^{\&prime;\&prime;},I^{\&prime;\&prime;}>0\end{array}\right]$

The then i-th grade of above power station of non-chopped-off head season adjusting function total storage outflow expectation value E (Q _i) be:

$E\left(Q_i\right)\underset{\&infin;}{\overset{\&infin;}{\&Integral;}}{I}_i\&CenterDot;f\left(I_i\right)\&CenterDot;{\mathrm{dI}}_i-I^{\&prime;\&prime;}\&CenterDot;\underset{\&infin;}{\overset{\&infin;}{\&Integral;}}f\left(I_i\right)\&CenterDot;{\mathrm{dI}}_i---\left(6\right)$

Wherein, f (I _i) be the probability density function of this i-th grade interval reservoir inflow in the above power station of non-chopped-off head season adjusting function.

6. a kind of Hydropower Stations power station according to claim 1 flood season optimum water level range control method, it is characterized in that: described step 5) in the defining method abandoning water risk in non-chopped-off head power station be:

First in interval reservoir inflow frequency curve, a certain swallowing-capacity I ' is found _i, make interval reservoir inflow I _ibe greater than this swallowing-capacity I ' _iprobability just in time for water risk P is abandoned in this non-chopped-off head power station expection _i: P (I _i> I ' _i)=P _i

According to principle of water balance, obtain i-th grade of non-chopped-off head power station expection and abandon water risk P _icorresponding optimum storage capacity V ' _i:

$V_i^{\&prime;}=V_{i,l}-({\stackrel{\&OverBar;}{Q}}_{i,\mathrm{perv}}+I_i^{\&prime;}-Q_{i,\mathrm{gen}})\mathrm{\&Delta;t}---\left(9\right)$

Wherein, be the expectation value of total storage outflow in upper water power station, i-th grade of non-chopped-off head power station, Q _{i, gen}i-th grade of non-chopped-off head Hydropower Plant completely sends out flow;

Again according to the water level-capacity property curve in this grade of power station, check in i-th grade of optimum storage capacity V in non-chopped-off head power station _ithe water level Z of ' correspondence _i', be the expection of this power station and abandon water risk P _icorresponding optimum reservoir level.

7. a kind of Hydropower Stations power station according to claim 1 flood season optimum water level range control method, it is characterized in that: described step 6) in do not possess the power station regulating above performance season storage outflow Q be: wherein, I is the average area reservoir inflow value over the years in this grade of power station this month, for the expectation value of total storage outflow in upper water power station.