JPS58223805A - Feedforward operation control system of plural sets of equipment - Google Patents

Abstract

PURPOSE:To ensure a simple and economical control for pump operation, by correcting the switching time point for number of operating devices so that a pump discharge volume accumulation curve never exceeds upper and lower limit load accumulation curves but just passes through these curves. CONSTITUTION:The information on the switching time point (corresponding to a black dot of operating device number time point 49) is neglected in an operation schedule to use only the information on combinations of pumps and their switching order. On the contrary, both combinations of pumps and their using orders are given as existing information. Based on the new estimated value of flow rate load (solid lines of load flow rate estimated value 48 and cumulative load flow rate estimated value 45), the switching time is momentarily decided (solid lines of pump discharge flow rate 47 and volume 42 obtained by adding initial storage volume 40 to the volume 47 and white dot of operating device number switching point 46). If a schedule is not obtained owing to a big difference between the new estimated value and the first estimated value, an operation schedule is decided again by a conventional method.

Description

[Detailed description of the invention] The present invention relates to "buffers (e.g. ponds, tanks).

A pond is provided on the suction side of the pump for the purpose of reducing the frequency of operation switching of multiple devices (e.g., pumps, blowers, refrigerators, etc.) and saving energy in a system with a heat storage tank, etc.) This will be explained using a drainage system as an example.

Conventionally, in a drainage system, a method of determining a pump operation schedule by controlling the number of operating pumps so that the internal water value, which changes over time depending on the inflow amount, falls within a certain range. No.) has been proposed. For example, (4ij Application No. 52-57716)
has also been proposed.

Figure 1 shows a model of the target water system. The purpose of pump operation control in this model is to prevent the reservoir 50, which stores water supplied from the inlet 500, from overflowing and to avoid emptying the reservoir under certain constraints (details will be described later) in this water system. The pump 51 is operated to discharge water to the outside water side 52 so as to fill the water.

This can be explained using Figure 2 as follows.In Figure 2, the horizontal axis is time (t), and the vertical axis is cumulative flow rate (t).
ΣQ).

First, a case where the actual lifting height is one foot will be explained. Curve 21 is a predicted cumulative inflow curve obtained by predicting the inflow into the reservoir from past results, and curve 22 is the cumulative predicted inflow amount plus the initial storage volume of the reservoir (upper limit prediction curve). be. The curve 23 is the predicted inflow cumulative value minus the storage capacity of the reservoir (lower limit predicted curve), and the curve 24 is the cumulative pump discharge volume (pump operating route). Empty the reservoir
In order to avoid this, the curve 24 must not exceed the curve 22, and in order to prevent the reservoir from overflowing, the curve 24 must not go below the curve 23. That is, curve 24
must be between curves 22 and 23.

Now, since it is assumed that the actual head is constant, the discharge amount per pump 11 is constant. Therefore, the cumulative discharge amount when a certain combination of pumps A, B, and C are operated can be represented by straight lines A, B, and C with a certain slope, as shown in FIG.

Further, the bending point of the curve 24 means a change in the number of operating pumps, speed, and blade angle. It is clear that the frequency of changes should be less in terms of maintenance of the pump equipment, and for this purpose, it is sufficient to find a curve 24 that is as long as possible.

To find the curve, the conventional method is to draw the cumulative discharge volume curve from the starting point for all combinations of installed pumps,
Find the point that crosses the song, 1Il122 or curve 23, repeat the same operation using that intersection as a new starting point, and find the one with the longest length from that point to the intersection, or the one with the least number of intersections. , or the one with the smallest cumulative evaluation value (for example, consumed energy) of each line segment was searched for as the curve 24.

The above control method can narrow down the number of candidates in advance by adopting a calculation (comparison of evaluation function values) to select a specific driving route, and a method using a dynamic programming method, for example, (fF Application Compared to No. 50-95867, the memory capacity and calculation time in the arithmetic unit can be reduced.

(b) In the calculation for selecting driving route candidates,
Since driving routes with bending curves are obtained as candidates only at the boundary defined by the upper limit curve and the lower limit curve, the driving route selected as a candidate is always the one with the least number of bends.

Therefore, the number of operations for switching the number of pumps, etc. is reduced, and
Control with less damage to the equipment is possible.

(c) The above can also be done when controlling the speed of the M pump.

(d) Changes in pump discharge amount due to changes in actual pump head can be taken into account.

Although it has advantages such as, it also has disadvantages such as.

(a) Since the predicted value of the inflow load is used to determine the pump operation schedule, if there is an error in the predicted value, there is a possibility that the pump cannot be operated properly with the determined operation schedule.

(b) The operation schedule is determined from the beginning every time the predicted value of the drifting load is revised from time to time, which takes calculation time, and the operation schedule determined in this way requires frequent changes in the number of vehicles. There is a high possibility that it will.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a simple and economical pump operation control system.

Hereinafter, the principle of the present invention will be explained in detail with reference to the drawings.

In the present invention, as shown in FIG. 4, it is assumed that the predicted value of the inflow load is updated every moment based on the latest information up to the time when the prediction calculation is performed. In FIG. 4, the dotted line shows the case based on the predicted value at time 1o, and the solid line shows the case based on the predicted value at time 's (
This is a case based on the predicted value in '1>to).

In Fig. 4(a), the horizontal axis shows time t, and the vertical axis shows cumulative flow rate Σ.
FIG. 4(b) is an explanatory diagram when the flow rate Q is plotted on the vertical axis in FIG. 87.

In FIG. 4, 41 is the actual measured value of the cumulative load flow rate, and 42 is the cumulative pump discharge flow rate plus the initial storage amount 4o'f, fc!
, 44 is the target storage amount, 45 t'j cumulative load flow rate prediction value,
46 is the switching point for the number of operating units, 47 is the pump discharge flow rate, 4si
, 1 load flow rate predicted value, and 49 is the operating number switching time.

The basic idea of the present invention is that the pump operation schedule (47, 42
The dotted line and 46(・ka) fr[J6
B. Egayayoyu. ,. [Yo, 1F Kawae Suruman] Mr. Weiji, who was in charge, was furious and asked what kind of JI was the combination of the pump pump.
Only the information regarding whether to switch at number B is used.

Conversely, given the combination of pumps determined in this way and the order in which they are used as known information, the number of pumps that overflow the reservoir is calculated based on the new predicted value of flow rate load (the solid line at 48 and 45). The switching time is determined from time to time so as not to run empty (the solid line at 47°42 and the O at 46).

If the new predicted value and the original predicted value are significantly different and the schedule cannot be determined using the initially determined pump combination and order of use, then the conventional Re-determine the driving schedule depending on the method.

Further, when the measured value of one water level exceeds a preset dangerous water level while operating the pump according to the operation schedule determined in this way, the system switches to conventional feedback control and returns the water level to a safe water level.

By adopting the above method, the following becomes possible.

(1) Even if there is an error in the predicted flow rate load value and the predicted value is revised from time to time, the operation schedule can be modified from time to time.

(2) In the case of (1) above, the operation schedule can be set while keeping the number of switchings small.

(3) In the case of (1) above, it is only necessary to re-determine the switching time instead of re-determining the entire operation schedule, so the calculation time is short and it is suitable for online control.

Hereinafter, the present invention will be explained in detail with reference to Examples.

As shown in FIG. 5, the feedforward operation control device for a plurality of devices according to the present invention includes a load prediction unit 1, an operation schedule determination unit 2, a switching time correction determination unit 3, an equipment controller 4, and a re-prediction determination unit. 5, a meter, and a detector 6. The switching time correction determination unit 3 includes an internal convex point search unit 31, a switching time correction unit 32, and a driving schedule additional calculation determination unit 33. The detector 6 detects the flow rate and water level status 210 from the process 7, and the equipment controller 4 transmits a start-stop signal 211 to equipment 8 such as a pump.

In FIG. 5, solid arrows indicate the flow of operation of the apparatus according to the invention, and dashed arrows indicate the flow of information. The operation of the device according to the invention will now be described.

In the load prediction unit 1, for example, Japanese Patent Application No. 53-13051
According to the method of No. 8, the inflow amount is predicted and its value is 201,
207 to the driving schedule determining section 2 and the re-prediction determining section 5, respectively. For example, in the driving schedule decision section 2, according to the method disclosed in Japanese Patent Application No. 153315-1980,
A schedule consisting of the switching time of the number of operating vehicles and the number of operating vehicles is determined and sent as information 202 to the internal convex point search unit 31 in the switching time correction determining unit 3, and a predicted value of the water level when operating according to the determined schedule is determined. , and send it to the re-prediction section/foot section 5 as a strange news 208.

The re-prediction determining unit 5 uses the information 209 of actual measured values regarding the inflow amount and water level status of the process sent from the detector 6, the predicted value 207 of the inflow amount sent from the load predicting unit 1, and the operation schedule determining unit 2. Predicted water level value 208 sent from
Then, the difference between the measured value and the predicted value is determined, and it is determined from time to time whether the difference is larger than the predetermined t value. If the difference becomes large, control is transferred to the load prediction unit 1 and the load is recalculated. Make predictions. In the case of re-prediction, the load prediction section 1 directly sends the re-prediction value 206 of the inflow amount to the internal convex point search section 31 of the switching time correction determination section 3 .

When the re-predicted value 206 is input, the switching time correction determining unit 3 empties or overflows the pond also for the re-predicted value.
In order to avoid this, the operating vehicle number switching time in the operation schedule 202 that has already been input is corrected.

Specifically, first, the internal convex point search unit 31 detects a convex point inside the area sandwiched between the temporal cumulative curve of the load re-prediction value 206 and the curve obtained by translating it by the pond storage capacity. Information that searches for a point and indicates that point 2゜3
Switching time correction section, send to □. The search method is to find the point where the rate of increase in the slope of the temporal cumulative curve is negative, and the point where the rate of increase in the slope of the temporal cumulative curve that is translated in parallel by the pond storage capacity is positive. by.

Next, control is transferred to the switching time correction unit 32, which first determines the intersection of the temporal cumulative curve of the predicted inflow value 206 and the cumulative pump discharge rate curve determined in comparison with the initial predicted inflow value 201. is at a different time from the intersection (i.e., the time when the number of pumps in operation is switched) determined corresponding to the first predicted inflow value 201, and then Modify the discharge amount cumulative curve (i.e., operating number schedule...switching time) as follows.

As a discharge amount cumulative curve after the switching time, (1) it has a slope corresponding to the discharge amount of the next number of pumps among the number of pumps determined in accordance with the first predicted inflow value, and (2) (a) A straight line passing through the area internal convex points searched by the internal convex point search unit 31, or (b) A cumulative curve of the discharge amount cumulative curve and the load re-prediction value before switching, or a parallel translation of it by the pond storage capacity. or (C) a straight line passing through a point on the cumulative discharge rate curve at the current time, of which (3) the straight line passing through the point on the cumulative discharge rate curve corresponding to the first predicted value. A straight line that has an intersection point after the current time, and (4) a straight line that does not intersect the upper and lower limit cumulative curve created from the re-predicted values for the longest time beyond a pre-given time,
to rope.

Here, if the gradient adopted in (5 bar υ) intersects the upper and lower limit cumulative curve within the pre-given time in (4), then in (13) the discharge amount of the next number of pumps is calculated. Adopt the slope corresponding to .

In addition, (6) The intersection of the straight line searched in this way and the discharge volume cumulative curve corresponding to the first predicted value becomes the new number switching time, but at that switching time, the pumps that had been operating up to that point If the operating time becomes less than the predetermined time in (4), select a straight line that does not intersect the second longest time upper/lower limit cumulative curve in (4).

However, (7) Even if the switching time is before the operation start time of the pump that had been operating up to that point, as long as the condition (3) (being after the current time) is satisfied. good.

(8) Repeat the above operations until the target aging is reached.

The switching time correction unit 32 outputs the driving schedule 204 determined above and sends it to the next driving schedule additional calculation determination unit 33.

The operation schedule additional calculation determination unit 33 checks whether the operation schedule 204 obtained by the switching time correction unit 32 has used up the slope of the discharge amount cumulative curve with respect to the first predicted value before reaching the target time. If it has been used up, control is transferred to the driving schedule determination unit 2 to perform additional calculations to determine a new driving schedule from that point onwards. If the schedule is still not determined, the control is still transferred to the driving schedule determining section 2 to re-determine the driving schedule from the current time.

Once all the operating schedules are determined, the information 205 is passed to the equipment controller 4.

The equipment controller 4 receives the operation schedule 205,
Signal 211 for supplying (starting) or stopping energy to the device 8
send.

The explanation so far has been made using a drainage system having a pond on the suction side of the pump as an example, but the present invention aims to reduce the frequency of shutting down multiple devices in a system with a sofa, save energy, etc. It can be used to control the operation of online correction type feedforward equipment.For example, it can also be used to control the number of blowers with air tanks, compressors of refrigerators, etc.

As explained above, according to the present invention, the following effects can be obtained.

(1) Even if there is an error in the predicted value of the inflow load, if the error exceeds a predetermined value, the pump operation schedule can be changed by re-predicting, allowing optimal pump operation. .

(, (2) Load. Heiko, 1. According to 1. 1, turn around.

Instead of re-determining everything, we use a method that changes only the number of pumps and the switching times of the schedule determined based on the initial predicted values, which shortens calculation time and makes online control easier. Available.

[Brief explanation of the drawing]

Figure 1 is a model diagram of the drainage system, Figure 2 is a discussion diagram of the pump operation schedule determination method, Figure 3 is an explanatory diagram of the relationship between Vi operation pump combinations and cumulative discharge volume, and Figure 4 is the principle of the present invention. The explanatory diagram, FIG. 5, is a block configuration diagram of an embodiment of the present invention. ′:! fJ l eye VJz diagram

Claims (1)

[Claims] 1. In a pump operation control device that prevents a reservoir from overflowing due to the inflow of a certain amount of water, the inflow flow rate of the load is predicted, and based on the predicted value, semi-optimal operation is determined by switching the number of operating units and the number of operating units. decide on the schedule,
When the difference between the predicted flow rate or water level when the pump is operated according to the determined operation schedule and the actual measured flow rate or water level becomes large, the load is re-estimated. Then, a lower limit load accumulation curve, which is the temporal cumulative value of the re-predicted load, and an upper limit load accumulation curve, which is shifted upward in parallel by the storage capacity of the pond, are created, and the pump is operated according to the above sub-optimal operation schedule. A feedforward operation control system for a plurality of devices, characterized in that the switching time of the number of devices in operation is corrected so that the discharge amount cumulative curve passes through the upper limit and lower limit load cumulative curve without exceeding the upper limit and lower limit load cumulative curve.