JPS5932014A - Pondage controller of reservoir group - Google Patents

Abstract

PURPOSE:To reduce the changing frequency of the water intake, the processed water volumn of a filtration plant, etc. and to facilitate the easy control as well as to prevent the exhaustion of a device, by deciding the volume of processed water of the water treatment plant from a cumulative curve, etc. of estimated total requirement of water of a reservoir and then delivering water to the reservoir. CONSTITUTION:The volume of processed water is decided from a cumulative curve, etc. of estimated total requirement of water of a reservoir and the water is delivered to the reservoir. For instance, a water demand estimating device 1 estimates in time eseries the general water demand of plural reservoirs on the basis of the actual demand. Then a calculating device 2 for processed water volume of water treatment plant calculates the planned value for the water intake and total pondage on the basis of conditions of facilities such as the total pondage, the upper/lower limit value of pondage, etc. A planned value storage device 3 stores the planned value of the water intake and the total pondage, and a plan correcting/deciding device 4 decides whether the planned value is corrected or not based on the planned value and actual value of the total pondage. When the correction is needed, a signal is sent to the device 1 to have rescheduling. When no correction is needed, the filtration plant is controlled in accordance with the planned value to actuate calculating devices 5-8 for inflow of reservoir.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for the amount of water stored in a group of water distribution reservoirs in a water supply facility.

[Background of the invention]

In water supply facilities, distribution reservoirs absorb fluctuations in demand and
It acts as a buffer to smooth water intake and water treatment plant operations. Conventional water storage control methods rely on the operator's experience.
Because it was difficult to comprehensively operate multiple water distribution reservoirs, their buffer function could not be fully utilized.

[Purpose of the invention]

The purpose of the present invention is to make full use of this function of the water distribution reservoir, thereby minimizing the frequency of changes in the amount of water intake, the amount of water treated at the water treatment plant, and the amount of water flowing into the water distribution reservoir, making control easier.
Another object of the present invention is to provide a water storage amount control device for a water distribution storage group that prevents equipment from becoming exhausted.

[Embodiments of the invention]

The present invention will be explained by taking the aqueous system shown in FIG. 1 as an example.

Raw water taken at a water intake plant 1 is purified at a water purification plant 2 and distributed to water distribution reservoirs 3 to 6. In order to smooth the operation of water intake and water treatment plants, comprehensive operation of the distribution reservoir group is required. Therefore, the distribution reservoirs 3 to 6 are considered as one large virtual reservoir 7. By using the buffer function of this virtual reservoir, it is possible to smooth water intake and water treatment plant operation.

■) Water intake plan, water treatment plant operation plan In the system shown in Figure 1, the amount of water intake and the amount of water treated at the water treatment plant are equal, so hereafter we will only discuss the amount of water treated at the water treatment plant.

It is assumed that the demand for each water reservoir can be predicted in a time-series manner by some method. The predicted demand value for the virtual reservoir 7 is obtained as the sum of these values. The amount of water treated by the water purification plant must be determined at each time so as to satisfy its own upper and lower limits, upper and lower limit constraints on the water storage amount of the virtual reservoir 7, and demand. Further, the upper limit and lower limit of the amount of water stored in the virtual water reservoir 7 are given by the sum of the upper limit and the sum of the lower limit in each region. As shown in Figure 2, a specific determination method is to calculate the purified water, which is created by adding the upper and lower limits of the water storage capacity of the virtual reservoir 7 to the cumulative demand curve 1 of the virtual water distribution reservoir 7. A band-shaped region sandwiched between a lower limit curve 2 for the amount of water treated at the plant and an upper limit curve 3 for the amount of water treated at the water purification plant is created, and a broken line 4 having an almost minimum number of changes in slope is found through this region. This polygonal line is a cumulative curve of the amount of water treated at the water purification plant 2 that should be determined. The slope of the broken line is the amount of water processed by the water treatment plant per hour. For example, Japanese Patent Applications No. 50-95867 and No. 50-1533 disclose methods for determining this type of broken line using cumulative curves.
There is No. 15. In this way, planned values for the amount of water treated at the water purification plant and the amount of water stored in the virtual reservoir 7 are determined for each time, and the amount of water taken into the water purification plant or the amount of treatment at the water purification plant is controlled. By doing this, changes in the amount of water treated at the water treatment plant can be minimized,
It is possible to prevent pump fatigue by reducing the operating labor of the water treatment plant and reducing the number of times pump-related equipment is switched. In addition, in FIG. 2, the difference between the polygonal line 4 and the curve 1 is the planned value Z (t) of the amount of water stored in the water distribution reservoir 7.

2) Online correction of planned values When operation is started based on the plan, a deviation occurs between the planned values and the actual values due to an error in the demand forecast. Calculate this deviation and modify the planned value using the following algorithm.

An actual measured value of the amount of water stored in the reservoir 7 is obtained from the sum of the measured values of the amount of water stored in the water distribution reservoirs 3 to 6. The planned water storage amount Z of this actual measured value
If the deviation from (t) is within the given tolerance range, then
No amendments to the plan will be made. ■) When the tolerance range is exceeded,
forecast and plan again using our algorithms.

3) Control of inflow into the reservoir based on the remaining water storage volume 1) or 2)
The inflow amount of the water distribution reservoirs 3 to 6 is controlled based on the planned water storage amount value 2 (shi) of the reservoir 7 and the demand forecast value, which were obtained in the above.

In order to reduce the frequency of control operations by utilizing the buffering function of a water distribution reservoir, as long as the amount of water stored in the reservoir is within the upper and lower limit constraints, the inflow amount from the previous time is maintained, and the amount of water that is about to go outside the upper and lower limit constraints is maintained. It is best to change it only when However, if this method is simply used, due to 2), the sum of the water storage volumes of reservoirs 3 to 6 (the virtual storage volume of reservoir 7) is limited, resulting in an imbalance in water storage volume between the reservoirs. In this case, there is a possibility that some distribution reservoirs will violate the upper and lower limit constraints. For example, in the following case.

Example] Water storage capacity of reservoir 7: 100 Upper limit of water storage capacity of distribution reservoir 3 = 50. Lower limit = 20 reservoir 4
II:40. II 20 Reservoir 5
l/:60. n 3Q water reservoir 6
tt:30. // 10 Here, water reservoir 5,
If the water storage amounts of reservoirs 6 and 6 are both equal to the upper limit, the sum of the water storage amounts of reservoirs 3 and 4 is 100-(60+30)=1
Must be set to 0. However, since the lower limit of water storage capacity of reservoirs 3 and 4 is 20 each, reservoirs 3 and 4 are
This would violate the lower bound constraint.

To solve this problem, we introduce the concept of residual water storage. The remaining water storage amount is a value obtained by subtracting the sum of the water storage amounts of the distribution reservoirs whose water storage amounts have already been determined from the water storage amount (already determined) of the virtual reservoir 7. Using this remaining water storage capacity, a new upper and lower limit is set for each reservoir in addition to the facility's upper and lower limits for water storage capacity, and if each reservoir satisfies the above criteria, all reservoirs will The facility should be able to satisfy the two lower limits.

The symbols used in calculations are explained below.

Z(t): Planned water storage amount of the virtual reservoir 7, Ri(t)
): Residual water storage volume, V i , V i : Reservoir 1 (i
= 1 to 4) upper and lower limits of water storage capacity on the facility, RV i ,
RV i : upper and lower limits of the water storage capacity of the water distribution reservoir 1 determined from the remaining water storage capacity, I(V i , LV i : water distribution reservoir i
The upper and lower control limits of the water storage amount (V ) T RV i
synthesized from sV i , RV i ) (t, −
1) It is assumed that the amount of water stored and the flow rate up to the time have already been determined, and the amount of water stored and the flow rate of the water reservoir 6 at the time have already been determined. (V6(t).Various types of water distribution reservoir 5)
Calculate the second lower eye as follows.

The remaining water storage amount R5 (t) is calculated as follows: R5 (t) = Z (t) - V6 (t) Using this,
New upper and lower limits of water storage capacity of the water distribution reservoir 5 are determined. (Figure 4)
.

RV5=R5(t)-(V3+V4)RV5=R5(
t)-(V3+V4) Further, upper and lower limit values for control are determined using the following equation.

HV5=Min (V5, RV5) LV5=Max
(V5, RV5) HV5. thus obtained.
Let LV5 be the upper and lower limit values for control of the water distribution reservoir 5 (see Figure 3 (
(see a), (b)).

Next, regarding the water reservoir 5, let be the inflow amount at time (t-1
) Calculate the predicted amount of water storage if the inflow rate is maintained (this can be easily determined using the predicted value of demand).

This is HV5. If the constraint of LV5 is satisfied, the inflow amount at time is determined to be equal to the inflow amount at time (t-1). HV5. If the constraint by L V5 is not satisfied, the inflow amount is changed so as to satisfy the constraint. Using the above algorithm, the inflow amount is determined sequentially from water reservoirs 6 to 3.

4) Control device FIG. 4 shows an example of a control device according to the present invention.

The device names are as follows.

■ = Demand forecasting device 2: Water treatment plant treated water amount calculation device 3: Planned value storage device 4: Plan modification judgment device 5 to 8: Water reservoir inflow calculation device In the diagram, solid lines indicate the flow of information, and broken lines indicate control signals. shall represent the flow of

The device 1 performs time-series prediction of the total demand of a plurality of water reservoirs based on the actual demand.

The device 2 calculates the predicted demand value, the total amount of water at the time of prediction,
Using facility conditions such as upper and lower limits of water storage as input signals, (1)
The planned values for dewatering amount and total water storage amount are calculated using the following algorithm. Device 3 stores the planned values calculated by device 2. The device 4 performs the following calculations at each sampling time. Using the planned value and actual amount of total water volume as input signals, (2)
The following algorithm is used to determine whether or not to modify the planned values.

If correction is required, a signal is sent to device 1 to enter the squirrel module. If no correction is required, the water intake and water purification plants are controlled according to the planned values, and at the same time, the devices 5 to 8 are activated.

The devices 5 to 8 calculate the inflow amount using the algorithm (3) using the total planned water amount, the calculated actual water storage amount, and the water storage amount of the distribution reservoir as input signals, and perform control based on this.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce the frequency of changes in the amount of water intake, the amount of water treated at the water purification plant, and the amount of water flowing into the water distribution reservoir, thereby facilitating control and preventing fatigue of equipment.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an example of a water system according to the present invention, FIGS. 2 and 3 are explanatory diagrams for explaining the present invention, and FIG. 4 is a configuration diagram of an example of a water storage amount control device according to the present invention. Show the diagram. 2: Water treatment plant treated water amount calculation device 5 to 8: Water reservoir inflow amount calculation device Fig. 1 fJ z Fig. 3 (0-) (b)

Claims (1)

[Claims] 11 of a distribution reservoir group consisting of a water treatment plant to supply water to multiple distribution reservoirs. In the water flow control device, a cumulative curve of the predicted 81g total demand amount, which is a change over time of the total predicted demand amount in each of the plurality of water distribution reservoirs, is determined, and the sum of the allowable lower limit values of the water storage amount of the plurality of water distribution reservoirs is determined. 2) to the predicted closed demand cumulative curve to determine the lower limit curve for the cumulative water treatment plant, and then add the sum of the allowable upper limit of water storage capacity of the multiple water distribution reservoirs to the predicted total demand cumulative curve. The water treatment plant's cumulative water treatment amount upper limit curve is determined by adding the water treatment plant's cumulative water treatment amount upper limit curve, and the water treatment plant's water treatment amount is determined by adding the water treatment plant's cumulative treatment water amount upper limit curve to the water treatment plant's cumulative treatment water amount upper limit curve. Water storage in a group of water distribution reservoirs, characterized in that the polygonal lines are located so that the polygonal line has a substantially minimum number of bends, and the determined amount of treated water is transmitted from the water purification plant to the plurality of water reservoirs. Volume control device.