JPH039483B2 - - Google Patents

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, water distribution reservoirs play the role of buffers that absorb fluctuations in demand and smooth the operation of water intake and water treatment plants. With conventional water storage control methods that rely on the experience of operators, it is difficult to comprehensively operate multiple water distribution reservoirs, making it impossible to fully utilize their functions as buffers. [Object 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 stored, the amount of water treated at the water treatment plant, and the amount of water flowing into the water distribution reservoir, thereby making control easier. It is an object of the present invention to provide a water storage amount control device for a water distribution storage group, which also prevents equipment fatigue. [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, consider the distribution reservoirs 3 to 6 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. 1) 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. Virtual reservoir 7
The demand forecast value 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 water storage amount of the virtual water distribution reservoir 7 are given by the sum of the upper limit and the sum of the lower limit of each pond. As a specific determination method, as shown in Figure 2, the cumulative demand curve 1 of the virtual water reservoir 7 is used.
Water treatment plant treated water amount lower limit curve 2 created by adding the upper and lower limit values of the water storage amount of the virtual reservoir 7 to
A band-shaped region is created between the curve 3 and the water treatment plant upper limit curve 3, and a broken line 4 with substantially the 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. Examples of methods for determining this type of broken line using cumulative curves include Japanese Patent Applications 1986-95867 and 1983-
There is number 153315. 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 so, changes in the amount of water treated at the water purification plant can be minimized, reducing the operational effort of the water purification plant and reducing the number of times pump-related equipment is switched, thereby preventing pump fatigue. 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 operations are started based on the plan, deviations occur between the planned values and actual values due to discrepancies 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. Of this actual value,
If the deviation from the planned water storage amount Z(t) is within the given tolerance range, the plan is not revised. When the tolerance range is exceeded, the prediction and plan are revised using the algorithm 1). 3) Control of inflow into the distribution reservoir based on the remaining water storage amount Based on the planned water storage amount Z(t) of the reservoir 7 obtained in 1) or 2) and the predicted demand value, the distribution reservoir 3 is
Control the inflow amount of ~6. In order to reduce the frequency of control operations by utilizing the buffering function of the water distribution reservoir, as long as the water storage volume is within the upper and lower limit constraints, the inflow amount from the previous time is maintained, and when the water is about to go outside the upper and lower limit constraints, it is necessary to 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] Reservoir 7 storage capacity: 100 Reservoir 3 storage capacity upper limit: 50, lower limit: 20 Reservoir 4 ″ : 40, ″ 20 Reservoir 5 ″ : 60, ″ 30 Reservoir 6 ″ : 30, ″ 10 Here, when the water storage amounts of the water distribution reservoirs 5 and 6 are both equal to the upper limit value, the sum of the water storage amounts of the water distribution reservoirs 3 and 4 must be 100−(60+30)=10.
However, since the lower limit of the water storage capacity of the water reservoirs 3 and 4 is 20 each, the water reservoirs 3 and 4 violate the lower limit constraint. To solve this problem, we introduce the concept of residual water storage. The remaining water storage capacity is the amount of water stored in a virtual reservoir7.
It is the value obtained by subtracting the sum of the water storage volumes of the distribution reservoirs whose water storage volumes have already been determined from the water storage volume (already determined). Using this remaining water storage amount, a new upper and lower limit is set for each distribution reservoir, in addition to the facility's upper and lower limits of water storage amount, and if each distribution reservoir satisfies this, all distribution reservoirs are The upper and lower limits above can be satisfied. The symbols used in calculations are explained below. Z(t): planned value of water storage amount of virtual reservoir 7,
Ri(t): Residual water storage amount i, Vi : Distribution reservoir i (i=
1 to 4) Facility upper and lower limits of water storage capacity, i,
RVi: Upper and lower limits of water storage in reservoir i determined from the remaining water storage, HVi, LVi: Control upper and lower limits of water storage in reservoir i (i, i, V i, R
(Synthesized from Vi) (It is assumed that the water storage amount and flow rate up to time t-1 have already been determined, and the water storage amount and flow rate at time t have already been determined for water distribution reservoir 6. (V6t) The various upper and lower limits of the water distribution reservoir 5 are calculated as follows. The remaining water storage amount R5 (t) is: R5 (t) = Z (t) - V6 (t) Using this, the water storage volume of the water distribution reservoir 5 is Find the new upper and lower limits for the amount (Figure 4). 5=R5(t)-( V3 + V4 ) RV5 =R5(t)-(3+4) Furthermore, the upper and lower limits for control can be calculated using the following formula. HV5=Min(5, 5) LV5=Max( V 5, RV 5) HV5 and LV5 obtained in this way are calculated as follows.
(See Figure 3 a and b). Next, regarding the water distribution reservoir 5, as the inflow amount at time t,
(Find the predicted water storage volume when the inflow rate at time t-1 is maintained (easily determined using the predicted value of demand). If this satisfies the constraints of HV5 and LV5, then the inflow volume at time t is determined to be equal to the inflow amount at time t-1. If the constraints by HV5 and LV5 are not satisfied, change the inflow amount so as to satisfy them. Using the above algorithm, The inflow amount is determined.Finally, we will provide a supplementary explanation of the method for determining new allowable upper and lower limits by correcting the upper and lower limits determined from the remaining water storage amount. <Assumptions> It is assumed that the total amount of water stored in the distribution reservoir (Z(t)) has already been determined in paragraphs 1) and 2). Reservoir number i = 1, 2,
..., n, and the water storage amount is determined from the larger number, and it is assumed that i=k+1, ..., n have already been determined. <Procedure for determining the allowable upper and lower limits of water distribution reservoir k> Step 1: Calculate the remaining water storage amount R _K of water distribution reservoir k. R _k (t)=Z(t)− _o 〓 ^i=k+1 V _i (t) (1) The second term on the right side is the determined water storage amount. Step 2: The amount determined from the remaining water storage amount of distribution reservoir k Calculate the lower limit. _k = R _k (t) − _k ― ₁ 〓 ⁱ⁼¹ V _i (2) RV _k = R _k (t) − _k ― ₁ 〓 ^i=1V _i (3) Step 3: (2), (3) The upper and lower limits in the equation are corrected to find new allowable upper and lower limits for control using the following equation. HV _k = M _io {V _k , RV _k } (4) LV _k = _Max {V _k , RV _k } (5) If the new upper and lower limits are satisfied, that is,
If the following formula LV _k VHV _k is satisfied, then V _k LV _k VHV _{k k} from formulas (4) and (5), so it is obvious that the upper and lower limits V _k and _k on the facility are satisfied. In the example of the present invention, the water distribution reservoir 6 is the first water distribution reservoir whose water storage amount is determined, and the determination procedure is as follows. R ₆ (t) = Z (t) (There is no determined distribution reservoir) (1)' ₆ = R ₆ (t) - ( V ₃ + V ₄ + V ₅ ) (2)' RV ₆ = R ₆ (t) - ( ₃ + ₄ + ₅ ) (3)' HV ₆ = M _io { ₆ , ₆ } (4)' LV ₆ = _Max { V ₆ , RV ₆ } (5)' 4) Control device No. FIG. 4 shows an example of a control device according to the present invention. The device names are as follows. 1: Demand forecast device 2: Water treatment plant treated water amount calculation device 3: Planned value storage device 4: Plan modification determination device 5-8: Water reservoir inflow calculation device In the figure, the solid line represents the flow of information, and the broken line represents the control signal. 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 planned values of the water intake amount and the total water storage amount using the algorithm (1) using the facility conditions such as the predicted demand value, the total water storage amount at the time of the prediction, and the upper and lower limits of the water storage amount as input signals. 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 storage as input signals, it is determined whether or not to modify the planned value using the algorithm (2).
If correction is necessary, a signal is sent to device 1 to enter rescheduling. If no correction is necessary, 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 planned total water storage amount, the calculated actual water storage amount, and the water storage amount of the distribution reservoir as input signals, and control based on this. [Effect of the invention] As described above, according to the present invention, the amount of water intake,
It is possible to reduce the frequency of changes in the amount of water treated at the water treatment plant and the amount of water flowing into the water distribution reservoir, making control easier and preventing equipment fatigue.

[Brief explanation of the drawing]

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 embodiment 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.

Claims (1)

[Claims] 1. In a water storage amount control device for a distribution reservoir group consisting of a plurality of distribution reservoirs and a water purification plant for supplying water to the distribution reservoirs, the predicted total demand amount is the change over time of the sum of the predicted demand amounts in each of the above-mentioned distribution reservoirs. means for determining a cumulative curve; and means for determining a cumulative water treatment plant lower limit curve by adding the sum of allowable lower limit values of water storage amounts of the plurality of water distribution reservoirs to the predicted total demand cumulative curve; Means for determining the cumulative treated water volume upper limit curve of the water treatment plant by adding the sum of the allowable upper limit values of the water storage volume of the water distribution reservoirs to the above-mentioned predicted total demand cumulative volume curve; Means for determining the curve so that the curve is a polygonal line located between the water treatment plant cumulative water treatment lower limit curve and the water treatment plant cumulative treatment water upper limit curve, and the number of bends is approximately the minimum, and based on the predicted demand curve. The above permissible lower limit value and allowable upper limit value are corrected based on the remaining water storage amount after subtracting the sum of the water storage amounts of the distribution reservoirs for which the water storage amount has already been determined, and the above polygonal line is changed according to the corrected values. 1. A water storage amount control device for a water distribution reservoir group, comprising means for sending a determined amount of treated water along a polygonal line from the water purification plant to the plurality of water distribution sections.