JPH0210660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling power generation when a plurality of power generation dams are installed on a river, and particularly to a method for determining a planned power output value.

Conventionally, when a plurality of power generation dams are installed on a river, the planned power generation output value has been determined for each power plant as follows.

(i) Initial water level H _s and terminal water level H _e of the power generation dam reservoir
Determine the planned value. The terminal water level _He is the water level at the terminal time that determines the power generation output plan. Usually, the initial water level H _s is the water level at 0 o'clock, and the terminal water level _He is the water level at 24 o'clock (0 o'clock the next day).

(ii) Calculate the predicted inflow amount Q _t at each time on the planning day. The predicted inflow value Q _t is determined by taking into account the actual inflow up to the previous day, the next day's weather forecast, and if there is a dam upstream, its discharge plan.

(iii) Convert the initial water level (H _s ) and final water level (H _e ) into reservoir storage capacity, and use the following formula to determine the usable water capacity (V _d ) for power generation on the planned day.

V _d = f _v (H _s ) − f _v (H _e ) + ₂₄ 〓 ^k=1 Q _k (1) Here, f _v is the conversion function of water level and storage amount,
This is determined from aerial surveys, etc.

( _iv ) The range of the upper limit value of the power generation amount (determined by the generation capacity of the generator or the permissible water supply amount of the water turbine, etc.) in order from the highest time period according to the predetermined priority order of the amount of water V d that can be used for power generation. Assign within. As shown in the example in FIG. 1, in a situation where full power generation is not possible over all time periods with the same priority, the average amount of water used for power generation is allocated to each time period. Let V _t be the amount of water used for power generation for each allocated time.

(v) Starting from the initial water level H _s , the inflow amount Q _t at each time
Then, from the power consumption amount _Vt , the reservoir water level schedule for the planned date is determined as shown in Figure 2A.

(vi) As in the example in Figure 2A, if a water level schedule that violates the constraints of the upper and lower limits of reservoir water level, H , is obtained, the water level schedule should be corrected so that the violation does not occur.

(vii) The amount of water corresponding to the correction in (vi) above is shown in Figure 2 B.
As shown by the arrow, allocate it to a time slot with low priority and plenty of time.

(viii) If the correction does not cause a violation of the upper and lower limits of the water level, the amount of water used for power generation V _t at that time is determined as the planned value.

(ix) If the water level upper and lower limit constraints are violated in the above, the same correction as in (vi) is repeated until the constraint violation no longer occurs.

The above-mentioned method for determining the planned power generation output has the following two problems.

First of all, each power station tries to use water as effectively as possible (by following the above procedure, the "ineffective discharge" of water flowing downstream for purposes other than power generation is reduced), but in doing so, , does not take into account the impact on downstream dams. Therefore, depending on the water storage status of the downstream dam reservoir, the downstream dam may discharge invalid water in situations that could have been avoided by adjusting the entire water system, which is a problem.

Second, the priority order for power generation in each time period is determined in advance, and the power generation output plan is determined based on the fixed priority order, making it difficult to coordinate with other water systems, thermal power, and nuclear power. This is a difficult point to take. When power demand fluctuates, the power demand as a whole will be met by accommodating each other with hydropower, thermal power, and nuclear power, but in that case, if the power generation output plan determined by the above procedure is corrected, The possibility of increasing ineffective discharge was a major problem.

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to determine the power generation output plan of each power plant after looking at the situation of the entire water system. In particular, when determining load sharing with other water systems, thermal power, and nuclear power, the state of the water system is aggregated into a single piece of information, the "capable power generation amount" for the planning period, to calculate the achievable power generation output target value. By determining the power generation output plan value based on this, the aim is to reduce the amount of ineffective discharge in the entire water system and promote the effective use of water.

A feature of the present invention is that even if the same amount of water is predicted to flow into a power generation dam reservoir, the amount of power generated depends on whether the reservoir is located further upstream or downstream. Focusing on the fact that the values are different when converted, we calculate that by the time the inflow to a certain reservoir reaches the most downstream point of the water system,
Convert that water into the power output that can be generated if it is used to the maximum extent for power generation. and,
By calculating the sum of the converted power generation capacity for all power generation dams and reservoirs in the water system,
The "capable power generation amount" of the water system is calculated, and that value is used as the target amount when determining the power generation output plan.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figure 3 shows an example of a water system in which multiple power generation dams are installed on a river. In the same figure, 1, 2
3 is a dam installed in series from the upstream side of the river. Each dam is equipped with a power plant indicated by 4, 5, 6, etc. Rainfall that falls in the upper reaches of this water system flows into Dam 1 through river channel 7. In addition, the amount of rainfall that falls around Dam 2 and Dam 3 is distributed directly or through tributaries.
It flows into dam 2 and dam 3, and their respective routes are represented by 8 and 9. Let the amounts of water flowing into the water system through these paths 7, 8, and 9 be r ₁ , r ₂ .r ₃ . Of the amount of water discharged from each dam, 1, 2, and 3, the amount of water used for power generation is assumed to flow through paths 10, 11, and 12, respectively, and each amount of water is expressed as q ₁ ,
Let q ₂ and q ₃ . On the other hand, the amount of invalid discharge from each dam 1, 2, and 3 is assumed to flow downstream through paths 13, 14, and 15, respectively.
Let g ₁ , g ₂ , g ₃ . In the description of Figure 3, the decrease in flow rate when water flows down along each river channel, so-called river channel loss, is ignored, but in rivers where this is noticeable, the river channel loss is discounted, and the following example is applied. It can be applied as follows.

The configuration of the present invention targeting the aqueous system shown in Figure 3 is as follows:
It is shown in Figure 4.

51, 52, and 53 in Figure 4 represent the inflow amounts to dams 1, 2, and 3 (r ₁ , r ₂ ,
_r3 ) is the calculation unit for the predicted value of the planning period. dam 1
FIG. 5 shows an example of a method for calculating the inflow predicted value. In Fig. 5, based on the inflow rate r ^s ₁ at the time of planning calculation for dam 1, and based on the weather forecast for the planning calculation period, when the weather forecast is rainy, a predicted value 102 is selected, which indicates an increasing trend in inflow rate. However, when it is cloudy, the planner selects the predicted value 103 to maintain the current state, and when it is sunny, the predicted value 104 is selected to indicate a decreasing trend. The predicted values at each selected time point are accumulated over the planning period using the following equation (2). However, r ^t ₁ is the dam 1 at time t.
is the inflow amount.

R ₁ = ₂₄ 〓 ^k=1 r ^t ₁ (2) The cumulative inflow amount R ₁ of the dam 1 determined by equation (2) is the output of the inflow amount prediction unit 51 in FIG. 4. Regarding the method of predicting the inflow amount r ^t ₁ mentioned above, conventionally,
There are various methods, and if a mathematical model for predicting inflow is derived based on predicted rainfall values,
It is also possible to determine r ^t ₁ using that formula. Also in the inflow amount prediction units 52 and 53, the prediction unit 5
In the same manner as in 1, the cumulative flow amounts R ₂ and R ₃ are calculated.

Next, the water amount/power generation amount conversion section 5 of the dam 1 in Figure 4
4, the cumulative inflow amount R ₁ is converted into power generation output. At this time, R ₁ is directly the amount of inflow into dam 1, but as shown in Figure 3, R 1
By passing 1 and 12, three locations 4, 5, and 6 can be used to generate electric power. Therefore, the conversion of R ₁ to power generation output is as follows (3)
It is done according to a ceremony.

P ₁ = (C ₁ + C ₂ + C ₃ ) R ₁ (3) Here, C ₁ , C ₂ , and C ₃ are power plant 1,
This is the conversion ratio of water volume and electricity in 2 and 3. Similarly, the water amount/power generation amount conversion unit 5 of dam 2 and dam 3
5 and 56, respectively, the cumulative inflow amount predicted value
From R ₂ and R ₃ , the possible power generation output amounts P ₂ and P ₃ are determined by the following equations (4) and (5).

P ₂ = (C ₂ + C ₃ ) R ₂ (4) P ₃ = C ₃ R ₃ (5) Note that C ₁ , C ₂ , and C ₃ are stored in the memory in the conversion unit 54,
C ₂ and C ₃ are stored in the memory of the conversion unit 55, and C ₃ is stored in the conversion unit 5.
6 memory.

Next, the possible power generation amount calculation unit 57 in FIG. 4 calculates the possible power generation amount of the water system as a whole.

P=α(P ₁ +P ₂ +P ₃ ) (6) α in equation (6) is the possible power generation coefficient.

In a simplified calculation, it can be ignored as α = 1, but normally, as shown in Figure 6, for example, the free capacity ratio V _R of each reservoir compared to when it is full is calculated.
α is determined according to a predetermined table as a function of . In Figure 6, the water storage volume ratio V _R of the water system is defined as (total storage volume of each reservoir at the time of planning/(total storage volume of each reservoir when it is full)), and if the ratio is 0.5 or less, that is, each reservoir When the free capacity of V R is large, the possibility of invalid discharge is small, so the potential power generation amount is not discounted by setting α = 1. When V _R is 0.5 or more, the possibility of invalid discharge increases, so α is reduced by that amount. Keep the value small.In this way, as in the example in Figure 6,
By predetermining the formula for determining the possible power generation amount coefficient α, the possible power generation amount calculation unit 7 shown in FIG. 4 can calculate the possible power generation amount P.

The specific calculation of α is performed as follows. Dams 1, 2, and 3 are equipped with water level detectors 70, 71, respectively.
72 is provided. The α calculation unit detects the outputs of the water level detectors 70, 71, and 72 at the time of plan calculation (23:00 on the day before the plan date), and calculates the water storage amounts V ₁ , V of each dam 1, 2, and 3 at that time. ₂ , calculate _V3 . Full water storage capacity of each dam ₁ , 2, 3 1, ₂ ,
₃ is stored in the memory within the α calculation unit 73.
The α calculation part is Calculate. The memory in the α calculation unit 73 has a sixth
A conversion table of the coefficient α for the water storage ratio V _R shown in the figure is stored in advance. With this conversion table,
Convert the ratio V _R calculated by equation (6′) into a coefficient α,
The α calculation section 73 outputs to the possible power generation amount calculation section.

The target power generation amount P ^t ₀ shown in FIG. 4 is determined based on the possible power generation amount of the water system determined by equation (6). The method for determining P ^t ₀ is, for example, as follows. FIG. 7 shows an example of the predicted value of the total power demand d ^t at each time t in the planning period. As in this example, the electricity demand is
It often fluctuates significantly over a 24-hour period. This fluctuating power demand will be met by combining hydropower, thermal power, and nuclear power generation in multiple water systems. Therefore, the target power generation amount P ^t ₀ of the water system at each time t is determined by the following equation (7).

In equation (7), the total power generation capacity P of the water system is distributed to each time period in proportion to (power demand at each time t d ^t )/daily power demand ₂₄ 〓 ^k=1 d ^k ). However, if it is necessary to increase the burden on hydropower during peak demand hours, the target power generation amount P ^t ₀ during peak hours is increased by a certain value, and the target power generation amount P ^t ′ ₀ during off-peak hours is increased.
It is also possible to make modifications such as reducing the amount by that amount.

Next, the power generation output plan calculation unit 59 in FIG. 4 determines the power generation output plan value for each power station based on the power generation target amount P ^t ₀ . When determining the power generation output plan value, it is desirable to determine a value as close as possible to the power generation target amount P ^t ₀ obtained above, and optimization calculation is required. For example, the calculation method is as follows (8)
Equations (9) to (13) are solved according to the linear programming problem (LP) solution method under the restrictions of equations (9) to (13).

However, min represents obtaining the minimum value.

In the above, equation (8) is the objective function equation for the LP problem,
Equations (9) to (13) are constraint condition expressions.

Below, equations (9) to (13) will be explained in sequence.

In equation (9), H ^t _i (i=1 to 3) is the water level of each dam reservoir, and H _i and _i are the lower limit of the water level, respectively.
This is the upper limit of the water level. In other words, Equation (9) represents a constraint that ensures that the water level of each dam reservoir falls within a limited range in each time period. Next, (10)
Equation (11) describes the temporal change in the water level of each dam reservoir. Here, A _i (i=1 to 3) is the water storage area of each dam reservoir, and ΔT is the time interval. Equation (10) relates to the most upstream dam, and is calculated from the inflow amount r _i to the power generation discharge amount q _i and the invalid discharge amount.
This indicates that the water level at the next point in time is determined by subtracting _g1 . In addition, in equation (11), assuming that the power generation discharge amount q _i-1 and the invalid discharge amount g _i-1 from the upstream dam arrive at the corresponding dam (i-th) after ΔT time, (10 ) expresses the relationship between changes in water level. When the time required for flowing down is twice or three times as large as ΔT, in equation (11), q ^t-1 _i-1 ,
Replace g ^t-1 _i-1 with q ^t-2 _i-1 , g ^t-2 _i-1 , or q ^t-3 _i-1
, it is necessary to modify the formula, such as changing it to g ^t-3 _i-1 .

Next, by equation (12), the power generation discharge amount used in equations (10) and (11) and the power generation output y ^t _i (i=1 ~3) Clarify the conversion function. The coefficient C _i (i=1 to 3) of equation (12) is
This is the conversion ratio between water volume and electric power used in equations (3) to (5) above. If the conversion ratio between the amount of water and electricity changes significantly depending on the amount of water used, the conversion ratio may be changed as a function of the amount of power generation and discharge q _i .

Next, equation (13) is the main objective of the present invention,
It represents the constraint conditions for minimizing the amount of invalid discharge for the water system as a whole. Here, ε _i (i=1 to 3)
is a value representing the limit value of ineffective discharge, and is normally set to ε _i =0 (i=1 to 3). However, always ε _i =0
If the constraint is fixed as (i = 1 to 3), in balance with other constraints in equations (9) to (12),
As a viable solution, the power generation discharge amount y ^t _i (i=1 to 3,
There is no guarantee that t=1 to 24) will always be found. This is the LP expressed by equations (8) to (13).
This means that the problem does not have a so-called feasible solution. As can be easily inferred, such a situation often occurs when the amount of inflow r ^t _i to each dam reservoir is extremely large.
Therefore, in equation (13), we introduce a parameter called the upper limit value ε _i of invalid discharge, and if equations (8) to (13)
If there is no feasible solution to the LP problem, ε _i
Let us iteratively solve the LP problem and find a feasible solution by gradually increasing the value of , for example by increasing the increment Δε _i . By doing the _above , a power generation output plan ^{y t} _{i (} i=1-3, t=1-24) can be determined.

As described above, according to the present invention, it is possible to express the state of the water system quickly and accurately as the amount of power generation possible, and as a result, unlike conventional methods, the amount of power generation from the water system is taken as a given condition. Rather than giving power, we use the amount of power that can be generated as a guideline to obtain a target amount of power generation that is coordinated with the pond water system, thermal power, and nuclear power, and plan and control the power generation output of each power station to maximize the target. becomes possible.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the output allocation method based on the priority of each time period in the conventional power generation output plan determination, and Figures 2A and B are water level Figure 3 is an explanatory diagram of the occurrence of overload and violation of upper and lower limits and its correction method.
The figure shows the configuration of an embodiment of the present invention, Figure 5 is an explanatory diagram of the method for determining the predicted value of inflow to each dam reservoir, and Figure 6 shows the water storage ratio and power generation capacity coefficient at the time of planning. The relationship diagram, FIG. 7, is an explanatory diagram of a typical power demand forecast value pattern.

Claims (1)

[Claims] 1. Predict the amount of water flowing into multiple power generation dams installed on rivers, determine the planned power generation output of the power plants installed at each dam based on the predicted amount of water, and calculate the power output of each power plant. This is a control method, and for a generator that can pass the water flowing into the upstream dam and the water flowing into the downstream dam before each water reaches the most downstream point, calculate the water volume vs. generated power conversion. The total power generation capacity of the entire water system is determined by converting it into power generation output using the ratio and integrating the converted power generation, and calculates the total power generation capacity obtained, the total power generation capacity of other water systems, thermal power, nuclear power, and electric power. 1. A power generation control method for a plurality of dams, characterized in that a power generation output target value of the water system is determined in relation to demand, and a power generation output plan value of each power plant is determined in accordance with the determined target value.