JPS6220562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Application of the Invention The present invention relates to a pump operation control method in a water system having ponds and rivers on the water intake side (inner water side) and the discharge side (outer water side). This pump operation control method can be used for water supply, sewage, irrigation, drainage, etc., but to simplify the explanation here, we will introduce ``operation control method using number control, speed control, and blade angle control of multiple pumps in a drainage pond.'' ” will be explained below as a specific example.

(2) Prior Art Conventionally, in drainage systems, in order to keep the internal water level, which changes over time depending on the amount of inflow, within a certain range,
For example, a method for determining the pump operation schedule by controlling the number of pumps in operation,
153315) (Special Publication No. 61-32681) has been proposed.

This control method has the following characteristics.

(a) In the inflow control method, the number of candidates can be narrowed down in advance by adopting a calculation (comparison of evaluation function values) that selects a specific driving route, which is different from conventional methods using dynamic programming methods. Compared to the method, for example, Japanese Patent Application No. 50-95867 (Japanese Patent Publication No. 61-32683), it is possible to reduce the amount of memory in the arithmetic unit and the calculation time.

(b) In the calculation to select driving route candidates,
Since the driving routes that make turns only at the boundaries defined by the upper limit curve and the lower limit curve are obtained as candidates, the driving route selected as a candidate is always the one with the least number of bends. Therefore, the number of operations for changing the number of inflow control devices, such as pumps, etc. is reduced, and control with less damage to the device is possible.

However, the above control method has the following problems.

(a) Since the amount of water discharged (discharge amount) is controlled by the number of operating pumps, large discontinuities occur in the amount of discharge due to starting and stopping of the pumps.

(b) When a large number of pumps are installed, the operation route is searched for all combinations, which increases the memory capacity of the computing device and takes a long computing time.

(c) Changes in pump discharge amount due to changes in actual pump head are not taken into consideration, and an operation schedule that does not match reality may be determined.

(3) Purpose of the Invention The purpose of the present invention was to solve the above-mentioned drawbacks of the prior art, and to provide a simple and economical pump operation control method.

(4) General explanation of the invention Hereinafter, the principle of the present invention will be explained in detail with reference to the drawings. Figure 1 shows a model of the target water system.

The purpose of pump operation control in this model is to drain water to the outside water side 52 in this water system without overflowing the reservoir 50 or emptying the reservoir, and satisfying constraint conditions (described in detail later). This is to operate the pump 51.

This can be explained using FIG. 2 as follows. First, a case where the actual head is constant will be explained.
Curve 1 is a predicted cumulative inflow curve obtained by predicting the inflow into the reservoir from past results, and curve 2 is the cumulative predicted inflow amount plus the initial storage volume of the reservoir (upper limit prediction curve). . Curve 3 is the predicted inflow cumulative value minus the storage margin of the water storage value (lower limit predicted curve), and curve 4 is the cumulative pump discharge volume (pump operating route). To prevent the reservoir from emptying, curve 4 must not exceed curve 2, and to prevent the reservoir from overflowing, curve 4 must not exceed curve 3. That is,
Curve 4 must be between curve 2 and curve 3.

Since it is assumed that the actual head is constant, the discharge amount per pump is constant. Therefore, the cumulative discharge amount when a certain pump combination A, B, and C is operated can be represented by a straight line with a certain slope as shown in FIG. Further, the bending point of the curve 4 means a change in the number of operating pumps, speed, and blade angle.
It is clear that the frequency of changes should be as low as possible from the viewpoint of maintenance of the pump equipment, and for this purpose, it is sufficient to find a curve 4 that is as long as possible.

Conventionally, the method for finding curve 4 is to find curve 2 or curve 3 for all combinations of installed pumps.
, and searched for curve 4, which has the longest length up to the point where it intersects. However, when the number of pumps increases, especially when pumps capable of speed control and blade angle control are added, it takes time to search for the above curve 4. this is,
This is because the speed and blade angle can be changed continuously, so searching for curve 4 using the conventional method corresponds to setting an infinite number of pumps.

As a method for quickly finding the operation route represented by curve 4, a pump operation restriction region such as curve 5 is determined using two parallel straight lines. This determination method is a feature of the present invention, and thereby not only reduces calculation time and memory, but also provides safety against prediction errors. The procedure for creating curve 5 is shown below.

(1) As shown in FIG. 4, create curves A and B corresponding to curves 2 and 3 in FIG. 2, respectively. This is because in actual pump operation, since the inflow amount is given as a discrete value, it is practical to show curves 2 and 3 as polygonal lines.

(2) Take any two sections in Fig. 4 and determine whether the above curves A and B are concave or convex in that section using the following formula.

Q _i T _i /T _i ≦Q _i+1 T _i+1 /T _i+1 ……Concave
(1) Q _i T _i /T _i >Q _i+1 T _i+1 /T _i+1 ……Convex
(2) (3) Determine whether a straight line can be drawn through the above two sections using the following formula. If the following formula is satisfied, a straight line passing through the two sections can be drawn.

In the case of concave: Q _i T _i +V/T _i ≧Q _i+1 T _i+1 −V
/T _i+1 (3) Convex case: Q _i T _i -V/T _i ≦Q _i+1 T _i+1 +V
/T _i+1 (4) (4) Create two parallel straight lines (pump operation constraint region determination curve, corresponding to curve 5 in Figure 2) in the above two sections as follows (see Figure 5). Below, Figure 5a
The method for creating two parallel straight lines will be explained in accordance with ~c for the case where the two sections are concave. The case of convexity can also be explained in the same way according to d to f of the same figure. Figure 5a
The pump operation constraint region is determined by connecting points 5 and 7 and creating a straight line that is parallel to the straight line and passes through point 2. In FIG. 5b, the pump operation constraint region is determined by extending a straight line passing through points 1 and 2 to the right end of the second section and creating a straight line parallel to the straight line and passing through point 7. Furthermore, in FIG. 5c, the pump operation constraint region is determined by extending a straight line passing through points 2 and 3 to the left end of the first section and creating a straight line parallel to the straight line and passing through point 5.

(5) Repeat steps (2) to (4) above between the constraint region obtained in step (4) above and the third section, and extend the constraint region until the width of the constraint region becomes less than or equal to a certain value. The reason why the width of the constraint area is maintained at a certain value or more is because if the width becomes narrow, when searching for a pump operation route within that range, there is a possibility that there is no operation route that falls within the constraint area.

If the pump operation constraint region can be determined as described above, the pump operation route is determined by selecting the pump combination (see Figure 3) that has the slope closest to the slope of the straight line indicating the constraint region in the corresponding constraint region section. Determine. That is, it is possible to determine a pump combination that results in a longer driving route.

Next, we will show how to modify the pump operating route when the actual head changes. This is because pumps have a characteristic that even if the same pump is operated, the discharge amount changes due to changes in the actual head. Even if the same pump is operated, if the discharge amount changes over time, the cumulative discharge amount shown in FIG. 3 will not be a straight line but a curved line. In other words, the pump operation route becomes a curve. In this case, correct the pump operation route using the following procedure (see Figure 6).

(1) Select the driving route that falls within the pump operation constraint region (curve 5) and that is closest to the slope of the straight line showing the constraint region in Figure 6, and extend the straight line (1) from time t ₀ .

(2) At time t ₁ , measure the internal water level, calculate the cumulative discharge amount up to time t ₁ from the difference from the internal water level at time t ₀ and the inflow amount, and calculate the value as a straight line at time t ₁ .
If it differs from the value in (1), correct it and make straight line 1'.

(3) Extend straight line 1' from the tip of straight line 1' to time _t2 . If the extended straight line goes outside the curve 5 between t ₁ and t ₂ , find a pump combination whose driving route is parallel to (or closest to parallel to) the curve 4, and determine the straight line 2.

(4) At time t ₂ , measure the internal water level and modify the driving route in the same way as in step (2) to make it straight 2'.

(5) Repeat the above steps at each internal water level measurement time.

(5) Embodiment Hereinafter, the present invention will be explained in detail with reference to the embodiment shown in FIG.

A load cumulative predicted value obtained by predicting the amount of inflow into the reservoir during the time period for which the operation plan is to be made from past actual volume is externally input to the load cumulative predicted value input device 101. In addition, pump characteristics, initial conditions, and constraint conditions are externally input to the respective input devices 102, 103, and 104. Based on the signals generated from these input devices, the driving route search device 105
Find a driving route. At this time, the time required to search for the driving route is shortened by using the above-described method for determining the pump operation restriction area. Next, based on the evaluation function signal from the evaluation function input device 107, an evaluation function value is determined for each determined driving route, the driving route where the value is maximum or minimum is determined, and the driving pump is determined by the driving pump determining device 106. decide. This result is output by the output device 108. The pump is operated based on this output, and the water level is measured after a certain period of time. If the water level deviates from the planned (calculated) value, feed back the water level and correct the driving route.

FIG. 8 shows a search flow of the driving route search device 105. In step 101, an inflow cumulative curve is created using an input signal applied from an input device. 10
In step 5, a pump operation restriction area is determined based on the signal applied from 101. In step 107, the pumped water amount is determined based on the signal applied from 105 and the signal applied from the pumped water amount determination rule 104. 106
Now, a characteristic curve of the combined pump is created using the input signal and the signal applied from the pump combination creation rule 102. At 110, a combination of operating pumps is selected from a plurality of types of pump combinations based on the signals applied from 106 and 107 and the signal applied from the operating pump transition rule 111. At step 112, a pump operation route is created based on the signal applied from step 110. When operating with the selected pump, if there is an error between the actual head before operation and the actual head after a certain period of operation, the actual head calculation 103, determination 109 whether the actual head is within the allowable range, and the pumping amount The operating pump is modified through modification 108 and the operating pump transition rule 111.

(6) Summary As explained above, the present invention is a method for controlling the number, speed, and blade angle of operating pumps, and its feature is that the storage capacity required for calculations is reduced, so the device can be made smaller. be. Another feature is that by measuring the internal and external water levels and feeding them back to the driving route search device, it is possible to control driving route correction.

[Brief explanation of the drawing]

Figure 1 is a model diagram of the drainage system, Figure 2 is an explanatory diagram of how to determine the pump operation schedule, Figure 3 is the operating pump combination and cumulative discharge amount, and Figures 4 and 5 are for determining the pump operation constraint area. FIG. 6 is an explanatory diagram of a pump operation route correction method when the actual head changes over time, and FIGS. 7 and 8 are diagrams of an embodiment of the present invention.

Claims (1)

[Claims] 1 In a pump operation control device for preventing a reservoir from overflowing due to an inflow of a certain amount of water, a lower limit prediction curve signal and the above predicted value signal are calculated from a load amount cumulative predicted value signal obtained by predicting the inflow flow rate from past results. and the upper limit prediction curve signal obtained by adding the initial water storage amount signal of the pond to the upper limit prediction curve signal, find a pump operation constraint region consisting of two parallel straight lines that pass between the upper limit and lower limit prediction curve signals, and are as long as possible, and within the constraint region. Based on the initial water storage amount signal, a driving route signal that bends only at or near the boundary determined by the upper limit and lower limit curve signals of the constraint area is generated, and among the driving route signals, the discharge A driving route signal in which the difference between the side water level and the water absorption side water level exceeds a predetermined value is corrected, a driving route signal that satisfies a predetermined evaluation function is selected from among the driving route signals, and the driving route signal is adjusted to the selected driving route signal. A pump operation control method characterized by controlling pump operation based on the following.