JPS5944643B2 - How to operate a water supply system in a water supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a water supply system in a water supply system.

The handling of water in waterworks is classified into the following processes: water intake, water storage, water conveyance, water purification, water transmission, and water distribution.

This article deals with water supply, but some water purification,
Includes matters related to water distribution. In other words, the water transmission system mainly consists of a water purification reservoir, a water distribution reservoir, a pump, and an electric valve, but in its operation, the operational characteristics of the water purification process and the water demand related to the water distribution reservoir must be fully considered. This invention relates to the operation of a water supply system for waterworks, and aims to optimally adjust the water volume of a pump and an electric valve under constraint conditions regarding water level and water volume.

Originally, water resources were indispensable for humans, and they lived in places where they could easily obtain water, but recently, as humans have concentrated in certain areas, the supply has become larger than the number of people living in the area. As the amount of water decreases, it becomes necessary to bring water from far away.

This is the reason why wide-area water supply systems emerged, and their primary purpose is to make effective use of limited water resources. Therefore, the above objective cannot be achieved by simply monitoring the pond water level and reducing or increasing the water amount when the operating water level reaches the upper or lower limit as in the past.

On the other hand, there is a possibility that there will be a growing trend of labor shortages, and it would be desirable to eliminate the need for operators to constantly monitor the situation, so it is conceivable to address this issue by introducing electronic computers. In this case, when determining the amount of water for the electric valves and pumps in the water supply system, the first thing to consider is to make it dependent solely on the empty capacity of the pond or only on the outflow amount of the pond. When determining the amount of water depending on the empty capacity of the pond, when the pond water level approaches the upper limit water level, the inflow amount must be set to a value close to zero. However, when the demand for water is larger than this value, the shortage must be supplied from the amount held in the pond, resulting in a sudden drop in the water level. Therefore, even in this case, it is preferable for operation to set the inflow amount to a value close to the demand water amount because water level fluctuations can be reduced. On the other hand, if the water level is dependent only on the outflow of the pond, the water level will rise and fall around the initial water level, and if the initial water level is low, there is a high risk that the water level will fall below the lower limit, so sufficient monitoring is required and the above conditions must be met. It will not be fully satisfied. Therefore, the purpose of this invention is to
When determining the amount of inflow into the pond, the demand water amount and the initial water level are taken into account, and the amount of adjustment is determined collectively every few hours, so that the pond water level is maintained at a medium level with fewer adjustments. The purpose is to ensure stable operation.

As shown in FIG. 1, a water supply system for implementing the present invention is comprised of a water purification reservoir 1, a water distribution reservoir 2, a pump 3, an electric valve 4, and a water level gauge 5 of the water distribution reservoir 2.

6 indicates a consumer group.

There are countless ways to combine these, including the number of units, but the combinations of water distribution reservoirs 2, pumps 3, and electric valves 4 other than the water purification reservoir 1 can be broadly classified into the following four types as shown in the figure. . (1
)Pump pressure transmission Water transmission from multiple reservoirs ()Pump pressure transmission Water transmission from distribution reservoirs (110 Gravity flow with water reservoir (Supported natural flow) For convenience of explanation, here, for convenience of explanation, the above water reservoir 2, pump 3, and electric valve 4 are connected to one water purification reservoir. Think about what each includes.

The pump 3 is driven by an induction machine, but the number of pumps is controlled by speed control. Operation commands are transmitted from a central monitoring room 9 having a central control panel 7 and a computer 8 by wireless or wired communication equipment, and operate the pumps 3 and electric valves 4 to adjust the amount of operation. On the other hand, since the water level and water amount are sent as data to the central monitoring room 9, operators need to be careful about the occurrence of abnormal situations. As an example, the water conveyance system considered here is one in which one of each of the four types is combined for one water purification pond 1 as described above. First, the amounts to be controlled and the constraint conditions for these four types of elements are described. The control method will be explained.

In the pump pressure feeding multiple reservoir water transmission method (1), multiple reservoirs 2
The inflow amount of the pump 3 and the discharge amount of the pump 3 must be determined.

That is, first, the discharge amount of the pump 3 must be determined, and then this value must be distributed to each reservoir 2 as the inflow amount. In this case, once the discharge amount of the pump 3 is determined, a command is issued to the 1 drive motor. This is an accompanying work. In number control, opening/closing commands are issued to the motor switchgear in order to operate the number of pumps corresponding to the pump discharge amount, and in speed control, commands are issued to the speed control panel in the form of changing the speed standard. The constraint conditions at this time are the maximum inflow of each reservoir 2,
These are the upper and lower limits of the operating water level, the maximum and minimum values of the pump discharge amount (pump speed control), or the quantized values (pump number control). Pump pressure distribution reservoir water transmission method (1
In 1), the pump 3 and the water distribution reservoir 2 are connected one-to-one, and the discharge amount of the pump 3 is equal to the inflow amount of the water distribution reservoir 2.

Therefore, the inflow into the distribution reservoir is determined from the demand water amount and the initial water level, and when the pump 3 is under speed control, it is confirmed that the pump discharge is between the maximum and minimum values, and then the pump discharge is adjusted to the inflow into the distribution reservoir. It should be equal to the amount. When the number of pumps 3 is controlled, the inflow amount into the water distribution reservoir may be determined to be the value that has the smallest absolute difference value from the quantized value of the pump discharge amount.
The constraint conditions at this time are the same as in the previous section (1), and are the maximum inflow of the water distribution reservoir 2, the upper and lower limits of the operating water level of the water distribution reservoir 2, and the maximum and minimum values or quantized values of the pump discharge amount. In the gravity flow system with a water distribution reservoir (I[), it is sufficient to determine the amount of water flowing into the water distribution reservoir 2.

The constraint conditions are related to the water distribution reservoir 2, and are the maximum inflow amount, the operating water level limit value, and the lower limit value. Gravity flow (IV) is uncontrollable.

In this case, the maximum flow rate of the water pipe is the constraint, but in reality it is included in the predicted water demand, and under the condition that the predicted water demand is given, the constraint is included in this predicted value. It is considered that the Next, let's think about water purification pond 1.

The sum of the inflow amounts at a certain time for the above four types of factors is the outflow amount of the water purification pond 1, and it is necessary to determine the inflow amount of the water purification pond commensurate with this. The constraint conditions in this case are the upper and lower limits of the operating water level regarding the water level of the water treatment pond. However, the amount of inflow into the water purification pond 1 is higher than that of the water purification pond. If the outflow amount is an integral multiple of the unit processing amount, such as in a filter pond (not shown), quantization must be performed. Next is the control method, which can be broadly divided into three types.

The first is a reduction in the number of changes in the manipulated variable, the second is an optimal method for determining the amount of water, and the third is related to processing of constraint conditions. The reduction in the number of changes in the manipulated variable was considered based on the actual water demand fluctuation curve, and the basic idea is as follows.

For the sake of convenience, the following explanation assumes that there are 24 hours in a day and that the water demand fluctuation curve is made up of 25 points, one point per hour. Ru. In other words, 1] A mouthful of catfish from a 7K cup. 1. ★ Add a water droplet to ensure that the borrowing is medium-cool.When the water level is low or high, it is sufficient to process this water level correction amount in a large or small amount in the first time interval. The optimal method for determining the amount of water is method (1) in Figure 1, in which the discharge amount of the pump 3 is distributed to multiple reservoirs 2, method (11), (IO distribution), etc. There are two ways to allocate the total amount of water in a day to each time interval in order to determine the inflow waveform to the water pond 2. Therefore, we will call the former spatial allocation and the latter temporal allocation. In the case of force equation (1) in FIG. 1, time allocation is performed to obtain a pump discharge amount curve, and then spatial allocation is performed to allocate to each water distribution reservoir 2.

First, I will explain time allocation. In a water supply system, this is used to determine the amount of inflow into a pond, so the total daily water amount is the sum of the total daily outflow from each pond plus the amount of water for mid-point correction of the pond water level. If there is, it will be distributed to the time interval determined by the above operation. Here, time interval 1 (i = 1, 2, ......, N
) is the value S(
=? (Qi-Qi) stain 1ai) is used.

This value S is minimized i- under the condition that the value (.Σ Ql) added over the entire time interval of the inflow amount Qi is constant QTl = 1N (QT = .Σ Qi).
:s: 1↓ Luck 2: Yield C: 2 2 = Demand: Since it has been formulated as an optimal allocation problem in a constant process, it is possible to obtain a solution using the dynamic programming method.

As a result, the inflow Qi as the solution obtained is obtained by subtracting (QT - Σ ql) the value NN (Σ Qi) added for each time period of the target value Qi from the daily total water volume QT, and calculating Mi 11: Ri: 1N Divide by the sum of the weight coefficients of the interval (Σ a1) and calculate the time i-
:． 1N Value multiplied by weighting coefficient al of section 1 (al/Σal);=
1 plus the target value (Qi=Qi+{Ai/
1NΣ a1}X{Q
T-. Σ Qi}).

The water level adjustment is dependent on 1=11=1, and the weighting coefficients a1 are all equal and may be set to 1.

However, in the first time interval (first (i21) time interval), the target value and weighting coefficient are adjusted to correct the water level. When the initial water level HO is low, the target value Q for the first time interval is the sum of the water demands DlN (=j?1d, where Dj is the hourly demand and the first time interval starts from the start time (J==O) and ends. Assume that the time is (J=n).

) to the water level correction amount QH (-{Ha-HO}×A; Ha
is the medium water level, and A is the pond area). (q12D1
+QH), and the weighting coefficient a1 is set to a value in which the sum of demand water quantities D1 is the denominator and the sum of demand water quantities D1 and the water level correction water quantity QH are the numerators (a1=(D1+QH)/D1). Therefore, by using these target value q1 and weighting coefficient a1, when the value obtained by the formula for the inflow amount Qi above becomes a large value and exceeds the allowable maximum amount of water passing through the water pipe, etc. (Qi>Qp), uses the maximum passing water amount Qp as the inflow amount Qi (Qi = Qp), and the shortfall (ΔQ-Q1-Qp) is calculated from the next time interval (1
-2), the target value Q2 and weighting coefficient A2 are similarly modified. Conversely, the initial water level H. When is high (HO>Ha), water level correction QH (-{HO-Ha}×A=-{Ha
−HO}×A) from the sum of demand water D, (=D
1-QH) is the target value q1, and the weighting coefficient a1 is the target value q
1 as the numerator and the sum of demand water D1 as the denominator (a1={
D1-QH}/D1). In this case, the target value q1 may be a negative number (when D1<QH), but in that case, the target value q1 is set to zero (q1-0) and the next time interval (
i-2) The water level can also be corrected. When controlling the number of pumps, the integer of the pump unit discharge volume (
(number of units) quantized to double the value. The same idea applies to spatial distribution. That is, in the method (1) of FIG. 1, the value obtained by adding the water level adjustment water amount to the section total water demand in the first time period is used as the target value when distributing the pump discharge amount in the first time period. A target value is used for the weighting coefficient. Therefore, in other time sections, the section total water demand is used as the target value, and this target value is also used as the weighting coefficient. Since the actual inflow amount is the amount of water per unit time, the value obtained by this calculation can be divided by the time interval. In this case as well, the maximum throughput may be exceeded in a certain distribution reservoir, but in this case, the excess amount is distributed to other distribution reservoirs according to their target values. This excess is corrected by taking into account the water level adjustment again as a target value in the next time interval. In this way, all water levels are maintained in the middle of the operational range as quickly as possible. As an example of this method, Figures 3a and 3b show the inflow, outflow, and water level changes for one pond. This invention is
The two key points are (1) reducing the number of switching operations, and (2) the optimal method of determining the inflow amount by allocating the water amount by combining the demand water amount and water level adjustment. Therefore, a modification will be shown and explained while taking into account the relationship with these two terms. (1) When there are multiple water treatment ponds in a water transmission system If there are multiple water treatment ponds 1 (Figure 1), one of the downstream component combinations ((1) (5)) There are times when water is sent from only a single water purification pond, and there are times when water is sent from multiple water purification ponds.

In the former case, since it is possible to group each water purification pond, a solution can be obtained by executing the above-mentioned calculation a number of times equal to the number of water purification ponds.
In the latter case, this method involves allocating the flow rate required by one set of component combinations to a plurality of water purification ponds, that is, by determining in advance the proportion of connections between the component combinations and the water purification ponds. It is possible to determine the flow rate by applying it as is. (2) When a part of the water supply system includes special elements.Special elements are the method shown in Figure 1 (1).
)()(IlXIV) An example of this is a water tank with an automatic opening/closing valve, and this method can also be applied when this is interposed between the water purification pond 1 and the pump 3.

That is, in this example, the inflow amount of the pump 3 does not become part of the outflow amount from the water purification pond, and the water amount one-time curve is slightly deformed. However, this is based on the premise that the outflow from a pond can be given an arbitrary water flow rate curve over time, so even if this type of element is included, there is essentially no problem with this method simply by adding this processing. It can be processed by (3) When connecting a gravity flow distribution pipe after the pump or electric valve In this case, methods (1) () (11) in Figure 1 can be considered, but by including the gravity flow, the pump discharge amount time curve It will change every unit time.

However, due to the inclusion of this natural flow, the water distribution reservoir flow rate and the sum of the natural flow flow must be constant for each unit time, so the water distribution reservoir flow rate is changed for each unit time. This eliminates the need to modify the processing for each time interval upstream. This is actually used for SCC (supervisory computer control) and DDC control (direct computer control). (4) Modification of unit time and study time In the above explanation, 24 hours a day (one point per hour) was targeted, but the unit time may be one point every two hours or one point every 30 minutes.

This simply depends on how the input data is input, and the calculation proceeds over this unit time. Moreover, the study time may be set to several days instead of one day, or even if it is set to several tens of hours, basically there is no need for any modification. The only modification required at this time is to change the instructions on how many time intervals to use and how many hours to calculate.
Determine the switching point using the extreme value midpoint method, select and set the number of switching points to suit the predicted water demand time curve, reduce the number of switching points, and then proceed with the calculation by moving to the next optimal allocation process. That's fine. (5) How to use the operating plan The invention described here is basically to obtain operational guidance and to show the operator the daily work contents.

However, methods for utilizing computers include SCC control and DDC.
There are controls, and the way they are used may change depending on your driving experience. Even in that case, the spatial distribution can be used as is. In other words, when the amount of runoff from a pond is distributed to several locations, spatial distribution can be used in any computer-based method. (6) Preparation of operation plan during dry season The dry season is about 10 days a year, and during this period, restrictions are placed on the amount of water flowing into water treatment ponds.

Even in such a case, it is possible to calculate the water supply restriction rate and obtain an operational plan with the water supply restriction in place without any modification. As described above, according to the present invention, by providing the predicted water demand time curve water supply system and the initial water level as input data, the water volume setting value of each electric pulp 4 and the pond water level at each time can be obtained as output data.

Moreover, the number of setting changes is small and the water level fluctuates around the middle of the operating range, so it rarely approaches the limit water level. Furthermore, since five types of driving plans are available, it is possible to select a driving plan by taking into account human conditions and other various conditions that cannot be considered as calculation conditions. This makes it possible to make the operator's work more appropriate and at the same time to be able to handle a wider range of tasks. In this way, it is possible to stably operate the water supply system and expand the work range of the operator, thereby increasing its utility value.

[Brief explanation of the drawing]

Fig. 1 is a system block diagram for explaining an embodiment of the operation method for earth water supply according to the present invention, Fig. 2a is a curve diagram showing fluctuations in water demand, and Fig. 2b is a diagram showing the sum of water demands. The curve diagrams shown in Figure 2c are time-water flow curve diagrams divided into time segments using the extreme value midpoint method, and Figure 2d is a curve diagram similar to Figure 2c in which the number of time segments is reduced. FIG. 3a is a time-versus-water flow curve diagram for explaining the relationship between pond inflow and outflow volume, and FIG. 3b is a curve diagram showing the pond water level versus time. 1...Water purification reservoir, 2...Distribution reservoir, 3...
...Pump, 4...Electric valve, 5...
・Water level gauge, 6... Consumer group, 7... Central control panel, 8... Electronic computer, 9...
Central monitoring room.

Claims (1)

[Claims] 1. When transmitting water from a water purification reservoir to at least one distribution reservoir via a pump and/or an electric valve, a variation curve of the amount of demand water distributed from the distribution reservoir to consumers over a period, for example, one day, is divided into multiple time intervals. After dividing the curve into a number of time intervals and decreasing the number of time intervals as much as possible, the predicted water demand fluctuation curve and the initial water level of the water distribution reservoir are centered at approximately the midpoint of each time interval of this fluctuation curve. A method for operating a water supply system in a water supply system, characterized in that a command to change the flow rate adjustment is given to the pump and/or the electric valve so that the flow rate value is determined from the water level and the water level correction.