JP2962931B2 - Dam Inflow Prediction Method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting the inflow of a dam, and more particularly, to the prediction of the inflow to a downstream dam, including an increase in flow due to rainfall, in a river that is systematically discharged from an upstream dam. In addition, the present invention relates to a dam inflow prediction method capable of correcting a predicted inflow due to rainfall as necessary.

[0002]

2. Description of the Related Art
Several methods have been proposed to calculate the discharge in the downstream river from the discharge of the dam.In general, the river from the discharge point of the upstream dam to the inflow point of the downstream dam, which is the predicted point, is expressed as a waterway, and this is expressed as a waterway. A method of obtaining a water flow by solving an unsteady non-uniform flow equation by modeling using a channel bottom gradient, water depth, and the like is used. However, there is a problem that the modeling of a river is usually not easy, and that this method requires much time for calculation. Further, as a method of calculating rainfall runoff or a method of correcting a prediction error, there is a method of sequentially and optimally using a Kalman filter in order to improve prediction accuracy, but generally has a drawback that the calculation is complicated.

[0003] The present invention has been made to solve the above problems, and an object of the present invention is to predict the inflow of a downstream dam with high accuracy by a simple and short-time calculation, and to utilize the downstream dam. It is an object of the present invention to provide a method for predicting a dam inflow which enables a plan to be formulated effectively and makes effective use of water discharge at an upstream dam. Another object of the present invention is to provide a dam inflow prediction method capable of correcting a prediction error by sequentially correcting a predicted inflow due to rainfall.

[0004]

According to a first aspect of the present invention, there is provided a dam predicting method for predicting an inflow into a downstream dam of a river which is intentionally discharged from an upstream dam. Predicted inflows from upstream dams, using actual discharges before and after planned discharges, estimated calculation time intervals, first-order lag time constants and dead time, actual rainfall and predicted rainfall Is calculated based on the sum of the predicted inflow due to rainfall obtained by using the tank model based on the above and the base flow based on the difference between the actual inflow and the predicted inflow before a certain period of time.

According to a second aspect, in the first aspect,
In accordance with the difference between the actual inflow amount and the predicted inflow amount at the time of the prediction, the predicted inflow amount due to rainfall obtained using the tank model is corrected.

[0006]

According to the first aspect of the present invention, first, (1) the upstream dam is determined by using q (t) including the actual discharge amount and the planned discharge amount to be discharged from the upstream dam at a certain time before the predicted time. The estimated inflow amount U (t) of the downstream dam caused by the discharge from the water is approximated to the first-order lag + dead time, and is calculated for each calculation time interval Δt using Expression 1.

[0007]

U (t + Δt) = U (t) + (Δt / T) {q (t−L) −U (t)}

Here, T is a first-order lag time constant, and L is a dead time until the water flow from the upstream dam affects the downstream dam. An approximate curve is created from these past data as a function of the predicted inflow amount U (t) of the downstream dam, and the data is stored in a storage device. The calculation time interval Δ
t is set sufficiently smaller than the first-order lag time constant T.

(2) A predicted inflow amount S (t) of the downstream dam due to rainfall is calculated for each calculation time interval Δt by using a tank model based on the past actual rainfall amount and the predicted rainfall amount. Here, the tank model is represented by a plurality of tanks arranged in series as shown in FIG. 3, and a rainfall amount for each time is input from above the uppermost tank. The rainfall input to the first tank is stored in this tank, and the difference between the stored height (outflow height) and the height of each hole is multiplied by the outflow coefficient of each hole, and the rainfall amount from the side hole is used. leak. The outflow from these side holes is the outflow downstream by the first tank. In addition, the water flowing out from the hole at the bottom permeates into the lower (second) tank.

In this way, the sum of the outflow amounts from the holes on the side surfaces of all the tanks becomes the outflow height, which is multiplied by the area of the basin to determine the inflow amount into the downstream dam. The time delay after rainfall is shorter as the water flows out from the hole on the side surface of the upper tank, and the time delay is larger as the water flows out from the hole on the side surface of the lower tank.
The number of tanks is usually two to four. In FIG. 3, XA, XB, XC are the outflow heights of each tank, HA
1, HA2, HB, HC are the heights of the holes on the side of each tank,
A1, A2, A3, B1, and C1 are the outflow coefficients of the holes on the side surface of each tank, and A0, B0, and C0 are the permeation coefficients of the holes on the bottom surface of each tank.

The actual and planned discharge q of the upstream dam
From (t), the predicted inflow amount U (t) of the downstream dam due to the discharge of the upstream dam is calculated for each calculation time interval Δt by the above-described first-order lag + dead time.

The predicted inflow S (t) due to rainfall calculated as described above and the predicted inflow U (t) of the downstream dam due to the discharge of the upstream dam calculated according to the above are combined to obtain the downstream dam inflow. At this time, the average value of the difference between the actual inflow amount and the predicted inflow amount several hours before the prediction time point is calculated, and this is set as the base flow rate V. At this time, if there is no outflow from the tank model several hours before the prediction point, the base flow rate calculated here is used assuming that the influence of rainfall has not been received, and this base flow rate is stored. If there is a runoff from the tank model several hours before the prediction point, the base flow already stored as being affected by rainfall is used.

As shown in the following equation 2, the final flow rate S (t) due to the rainfall and the predicted flow rate U (t) due to the discharge of the upstream dam and the base flow rate V are used to calculate the final flow rate. And the downstream dam predicted inflow R (t).

[0014]

## EQU2 ## R (t) = S (t) + U (t) + V

(3) In the second invention, when the predicted inflow is corrected based on the actual inflow, the predicted inflow R (k) and the actual inflow Q (k) at the prediction time k are used. Equation 3
, And only the predicted inflow S (t) due to rain, which is predicted and calculated using only the tank model, as shown in Equation 4, as a time reduction function, is used as a new downstream dam predicted inflow. Note that the correction calculation interval in this case is longer than the previous calculation time interval Δt.

[0016]

Α = {Q (k) −R (k)} / S (k)

[0017]

R (k + i) = {1 + αe- ^{t / T1} } S (k + i) + U (k + i) + V

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a flowchart showing an embodiment of the first invention. First, using the actual rainfall amount in the actual rainfall amount storage file 11 and the predicted rainfall amount in the predicted rainfall amount storage file 12, a predicted inflow amount S due to rainfall is calculated by a tank model.
Only (t) is calculated (step S1). At this time, the tank model coefficient stored in the tank model coefficient file 14 is referred to. Next, the planned discharge discharge storage file 13
Using the planned discharge amount of the upstream dam stored in the storage area and the actual discharge amount in the storage device (not shown), the predicted inflow amount U (t) due to the discharge is calculated by Equation 1 using the river channel model ( S2). At this time, the primary delay time constant T in the river channel model primary delay time constant file 15 and the dead time L in the river channel model dead time file 16 are referred to.

If there is an outflow from the tank model several hours before the forecast point, the base flow rate V already stored in the base flow rate file 17 is assumed to be affected by rainfall.
, The calculation of the base flow rate becomes unnecessary (S3N
O) The process moves to step S5 described below. If there is no outflow from the tank model several hours before the prediction time point, it is assumed that there is no influence of rainfall, and the inflow amount due to rainfall and the inflow amount due to discharge are subtracted from the actual inflow amount, and the base flow rate V (S3
YES, S4). The base flow rate V is stored in the base flow rate file 17.

Since the first-order lag time constant T and the dead time L of the river channel model are functions of the discharge, the river channel model is again calculated using the predicted inflow, and the predicted inflow U due to the discharge at the upstream dam is calculated again. (t) is calculated (S5). Thereafter, a final downstream dam predicted inflow R (t) is calculated from the sum of the predicted inflow S (t) due to rainfall, the predicted inflow U (t) due to upstream dam discharge, and the base flow V (S6). .

FIG. 2 is a flowchart showing an embodiment of the second invention. In this embodiment, a predicted inflow R (t) is calculated from the sum of the calculated predicted inflow S (t) due to rainfall, the predicted inflow U (t) due to discharge, and the base flow V, and the actual inflow storage is performed. Whether correction is necessary or not is determined based on the difference from the actual inflow amount in the file 18 (S41), and if necessary (S41Y).
ES) The correction coefficient α is calculated by the above equation 3, and the correction is performed by the equation 4 (S42). If no correction is needed (S
41 NO), the flow proceeds to step S5 without performing the correction calculation of the correction coefficient and the inflow amount.

FIG. 4 is a prediction result according to the first embodiment of the present invention. The actual value (solid line) and the predicted value (solid line) of the rainfall, the upstream dam discharge, and the downstream dam inflow during a period of low rainfall are shown. ). For the inflow before rainfall, the predicted inflow is calculated from the discharge of the upstream dam by the first-order delay of the river channel model + the dead time. FIG. 5 shows prediction results according to the embodiment of the second invention, and shows actual values and predicted values of rainfall, upstream dam discharge, and downstream dam inflow during heavy rainfall. As is clear from this figure, the predicted value is close to the actual value by performing the correction according to the present invention for the rapid increase in rainfall. FIG. 6 shows a prediction result when the correction is not performed under the same conditions as in FIG. 5, and it can be seen that the prediction accuracy is deteriorated for a sudden increase in the amount of rain as shown in FIG.

[0023]

As described above, according to the first aspect of the present invention, the predicted inflow due to the discharge of the upstream dam obtained by a simple calculation, the predicted inflow due to rainfall obtained by using a tank model, and the base flow rate As a result, the predicted inflow amount at the downstream dam can be obtained, so that the inflow amount can be predicted in a short time without creating a river model as in the related art.
As a result, an effective utilization plan for downstream dams can be formulated,
In addition, water discharge from upstream dams can be used effectively. According to the second invention, in addition to the above effects, the prediction accuracy can be greatly improved by sequentially correcting the predicted inflow amount, and the calculation is simplified as compared with the conventional method using a Kalman filter or the like. There is an effect that it can be made.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of the first invention.

FIG. 2 is a flowchart showing an embodiment of the second invention.

FIG. 3 is an explanatory diagram of a tank model.

FIG. 4 is a diagram showing a prediction result according to the embodiment of the first invention.

FIG. 5 is a diagram showing a prediction result according to the embodiment of the second invention.

FIG. 6 is a diagram illustrating a prediction result when the predicted inflow amount due to rainfall is not corrected under the same conditions as in FIG. 5;

[Explanation of symbols]

 11 Actual rainfall storage file 12 Predicted rainfall storage file 13 Planned discharge discharge storage file 14 Tank model coefficient file 15 River channel model first-order lag time constant file 16 River channel model dead time file 17 Base flow rate file 18 Actual inflow storage file

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideaki Kirino 1 Fuji Town, Hino City, Tokyo Inside Fuji Facom Control Co., Ltd. (56) References JP-A-50-73430 (JP, A) JP-A-59- 154504 (JP, A) JP-A-1-191210 (JP, A) JP-A-5-125713 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B05B 17/00-17 / 02 B05B 11/00-13/04 E02B 7/00 B05D 7/06

Claims (2)

(57) [Claims] 1. A dam inflow predicting method for predicting an inflow into a downstream dam of a river that is systematically discharged from an upstream dam, comprising: an actual discharge before and after a predetermined time; The estimated inflow due to the discharge of the upstream dam calculated using the interval, the first-order lag time constant and the dead time, and the estimated inflow due to the rain obtained using the tank model based on the actual rainfall and the predicted rainfall. A dam inflow predicting method, characterized in that a downstream dam predicted inflow is obtained by the sum of a base flow based on a difference between an actual inflow and a predicted inflow before time, and 2. The dam inflow predicting method according to claim 1, wherein the predicted inflow due to rainfall obtained by using the tank model is corrected according to a difference between the actual inflow and the predicted inflow at the time of the prediction. Characteristic dam inflow prediction method.