JPS6162115A - Water level control method for dam reservoir - Google Patents

Abstract

PURPOSE:To prevent the occurrence of vibration of gate and water level caused by over control and to realize appropriate level control by refraining the next control until the time when the result of gate opening/closing control affects the change of water level. CONSTITUTION:Firstly, a present water level H(t0) and a present water flow volume Q0(t0) are inputted, and in considering with a previous water level H(t-1) and a target level H, the necessity of gate control is judged. And if it is judged to be necessary, the gate control is executed and the flow volume Q0'(t0) after the control is inputted. Next, the next control time t1 is worked out, and the control is suspended for the time (t1-t). If it is judged that gate control is unnecessary, the control is suspended for the time of sampling cycle. Thus occurrence of vibration of water level and gate caused by over control is avoided and appropriate water level control is realized by refraining the next control until the time when the result of gate opening/closing control is reflected to the change of water level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a water level control method for maintaining a constant water level in a dam reservoir.

[Background of the invention]

How to control dam gates safely and accurately is an important issue in line with the automation and labor-saving measures that have become popular in recent years.

In particular, it is necessary to keep dam water levels high in preparation for hydroelectric power generation and water utilization, and to keep dam water levels low in preparation for flooding. In order to achieve this, a target water level is set in advance, the water level of the dam is detected at regular intervals, and a gate is operated according to the gradient of change in this water level or the deviation from the target water level, and the water level of the dam is adjusted. A constant water level control method is usually used to maintain the water level at a target level.

Here, an example of a conventional constant water level control method will be described. Generally, when controlling the current water level to the target water level, as shown in Fig. 5, control bands (hereinafter referred to as control bands) 1, 2 of a predetermined width that are vertically symmetrical with respect to the target water level are prepared for each target water level. .3 is determined in advance, and the control judgment as shown in the figure is made based on the current position and past water level gradient (arrow in the figure).

In FIG. 5, the * mark indicates the current water level, the X mark indicates when no control is performed, the ○ mark indicates when control is performed, and ■ indicates that control is performed when the water level changes rapidly.

FIG. 6 shows a method for determining the control amount when the water level moves away from the target water level. The horizontal axis shows time, the vertical axis shows water level, and t
o, tl, and t2 indicate control sampling times. The control amount at the current time t1 is determined as follows. In other words, if there is no sudden change in flow rate, the water level Ht at tl becomes Htz'(Hh'
=2Hh Ht6), and at the next control sampling time Ht x'(Ht"=Ht
1-Δh, ) is determined. It is expressed by the tsumushimo formula.

However, Qo is the current discharge amount, f(H) is the dam total storage amount calculation formula when the water level is H, and t is the control sampling time.

Note that Δhi is determined by the control band width ΔHr.Δhi=
f(ΔHi)L, Δhi≦Δh2≦Δh3...
≦Δhi.

Next, FIG. 7 shows a method for determining the control amount when the water level approaches the target water level by two levels. In Figure 7, Hlo Htr
When ≦Δh, no control is performed, and the control amount is calculated by the equation (Tokisumi) where Hto Htt>Δh2, and control is performed.

An example of an automatic gate control device using the above control method is shown in Section 8.
As shown in the figure. The water level data measured by the water level gauge 4 is subjected to a predetermined calculation by the gate opening command device 5 via an addition element, and the gate drive motor 2 is driven and controlled by the control command signal, and the gate 1 is adjusted to open or close. . 3 is a gate opening degree meter, which is used for correction.

Now, in the conventional method described above, when the water level is sampled at time t2, which is a further time ΔT after the gate control is performed at drop time 11, if ΔT is too small compared to the flooded area, then at time t1, the water level is sampled. Before the result of changing the discharge amount is reflected in the water level, the same control is repeated at time t2, resulting in an excessive control amount, which may cause vibrations in the water level and the gate. An example of this is shown in FIG.

FIG. 11 is a graph showing the relationship between time t, discharge amount Qo, and water level H. In section (2), the water level deviates significantly from the target water level Ha, so the discharge amount is continuously increased. In the section (■), the control was stopped because the water level was approaching the target water level, but the gate was too open in the section (■), so it was closed again in the section (■). By repeating such operations, vibrations of the gate and water level occur, which is undesirable in terms of downstream effects and equipment life.

The reason why such a gate vibrates is that in order to prevent erroneous control due to small movements such as ripples on the water surface, the accuracy of general water level gauges is relatively coarse scale (approximately ICrn).
This is because the control computer continues the control until the water level changes by this amount. As a result, overcontrol occurs and gate vibration occurs.

On the other hand, if ΔT is too large, there is a risk of a control delay occurring when the inflow rate is changing rapidly.

In this way, it is undesirable if the water level sampling period ΔT is inappropriate, but since the optimal ΔT changes depending on various conditions such as inflow volume, discharge volume, and flooded area of the dam, gate control is performed at a constant cycle. In conventional methods, some degree of vibration is unavoidable.

In addition, as an example of preventing repeated opening and closing operations of the gate due to ripples on the water surface, etc.,
There is something disclosed in the publication No.

Furthermore, Japanese Patent Publication No. 44-23693 discloses an example of controlling the opening and closing of a gate by detecting temporal changes in the amount of water flowing into a dam and predicting changes in water level.

[Purpose of the invention]

The purpose of the present invention is to prevent water level and gate vibration from occurring.
The objective is to provide an optimal constant water level control method.

[Summary of the invention]

In order to achieve the above object, the present invention provides a water level control method for maintaining a constant water level in a dam reservoir by opening and closing a gate of a dam, in which the result of controlling the amount of water released by controlling the rotation of the gate is as follows. This system is characterized by providing a period during which control of the increase or decrease in the amount of water released is suspended until the time when the change in water level in the dam reservoir is reflected.

More specifically, the period during which control of increase/decrease in water discharge amount is suspended is as follows:
The amount of water between the current water level and the target water level is calculated by multiplying the flooded area at each water level of the dam reservoir by the water level fluctuation due to the release of a specified amount of water, and then divides this water amount by the change in the amount of water released over a predetermined time. The amount of water between the determined current water level and the target water level is taken as the time required to discharge the water.

[Embodiments of the invention]

Next, an embodiment of the water level control method for a dam reservoir according to the present invention will be described based on the drawings.

First, the control principle according to the present invention will be explained. FIG. 1 is a graph showing the relationship between time t, inflow amount Q' + outflow amount QO1, and water level H. At time t0, the discharge amount Qo(t
If o) is not changed, the water level at the next sampling time t1 can be estimated to be H(t+).

This value is calculated as follows, where Qi(to) is the inflow i at time io, H(to) is the water level, and A(H(to) is the flooded area at the water level H(to)). ) Deroru.

Next, time 1. If the discharge fttQo (to) is changed to Qo/(to) in , it can be estimated that the next water level is u'(tl). This value is...
...(2) becomes.

Therefore, water by varying the discharge amount
The variation ΔH at the 6' position is calculated from equations (1) and (2),
It can be estimated that (3).

Now, assuming that the minimum unit for detecting the water level is ΔHvrb in , by replacing ΔH in equation (3) with ΔHrrL in , the time t1 at which the gate control at time to is reflected in the water level change can be found. Therefore, 11 of equation (4) is the optimal time at which the next water level change should be detected and control should be performed.

Note that ΔHmin is a value determined by a water level gauge, and is usually 1 crn.

Furthermore, when gate control is performed at time 11 to change the discharge amount from t''Qo(tt) to Qo'(tl), the time t2 to be controlled next is similarly, but the time If gate control is not performed in step 11, the sampling period is returned to the normal sampling period ΔT and tji"tl +
ΔT (6). This sampling period ΔT is set to a sufficiently rapid value so that detection of water level changes is not delayed. FIG. 2 shows an example of the relationship between the control time t and the discharge amount QO in the case of the present invention. Second
■ and ■ in the figure are the times when gate control was performed and the discharge amount was changed, and ■.

■ is the control time calculated based on equation (4) when gate control is performed in ■ and ■. On the other hand, Figure 3 shows the second
This is an example of a conventional method under the same conditions as in the figure. In Figure 3, the control at time ■, ■, ■, ■, ■, 10 is as follows.
This is a wasteful control that occurs because the sampling period is too short. As described above, in the case of the present invention, the next control is not performed until the result of the gate control is reflected in the amount of water level change.

Therefore, it is possible to eliminate unnecessary control and prevent vibrations of the gate and water level. In other words, not performing control during time 11 shown by equation (4) means that gate control signals are not output in the gate opening command devices 5 to 7 (Fig. 8), and the water level detection is not performed. This means suppressing overcontrol based on delays. Therefore, the opening and closing of the gate is not repeated more than necessary, and vibration can be prevented.

FIG. 11 is a flowchart showing an embodiment of the present invention.

In step 8, the current water level H (to) and current discharge amount QO (to) are input, and in step 9, the previous water level H (t-1) and target water level HO are taken into consideration to determine whether gate control is necessary. to judge. The determination method may be the same as the conventional method (FIGS. 5 to 9). As a result of the judgment, if gate control is necessary, control is executed in step 10, and step 11 is performed.
Input the controlled discharge amount Qo'(to). Further, in step 12, the next control time t1 is determined using equation (4), and in 13, the process waits for a time (ts t), and returns to the process of step 8. On the other hand, as a result of the determination in step 9, if gate control is not required, the process waits for ΔT in step 14 in order to set the sampling period to the normal value ΔT, and returns to the processing in step 8.

[Effects of the Invention] As described above, according to the present invention, the control is stopped until the time when the result of the gate opening/closing control is reflected in the water level change, and the control is stopped until the next control or time. This enables optimal water level control that can prevent the occurrence of vibrations.

[Brief explanation of the drawing]

Figure 1 shows the method of setting the pause period in the water level ftTIJ control method according to the present invention. is a graph diagram showing the change in discharge amount due to the conventional control method in comparison with FIG. 2, FIG. 4 is a flowchart showing the processing procedure of the control method according to the present invention, and FIG. Fig. 9 is a block diagram showing an example of a conventional control procedure, Fig. 10 is a flowchart showing a conventional calculation procedure for target flow rate calculation, and Fig. 11 is a relationship between time, discharge amount, and water level. FIG. 1...Dam, 2...Gate drive motor, 3...
Gate opening degree meter, 4... Water level gauge, 5, 6.7... Gate opening degree finger. control device, 12...optimum control time calculation step, 13
...Waiting time step, 14...Waiting time step.

Claims (1)

[Claims] 1. In a water level control method for maintaining a constant water level in a dam reservoir by opening and closing a gate of a dam, the result of controlling the amount of water discharged by controlling the gate opening degree is a change in the water level in the dam reservoir. A water level control method for a dam reservoir, characterized by providing a period during which control of increase/decrease in the amount of water discharged is suspended until the time when the next water discharge amount is reflected. 2. In the water level control method according to claim 1, the period during which the water discharge amount increase/decrease control is suspended is determined by the product of the flooded area at each water level of the dam reservoir and the water level fluctuation due to the discharge of a predetermined water discharge amount. The time required to discharge the amount of water between the current water level and the target water level, which is obtained by calculating the amount of water between the current water level and the target water level, and dividing this amount by the change in the amount of water discharged over a predetermined time. water level control method for dam reservoirs.