JPH01245314A - Device for controlling the number of rain-water pumps - Google Patents

Abstract

PURPOSE:To suppress the start/stop of an unnecessary pump and to allow rain- water pumps to safely correspond even to the sudden increment of an inflow rate by controlling the number of pumps in consideration of an inflow rate estimate even in a transient period turning a pump discharge valve from its slightly opened state to a fully opened state. CONSTITUTION:When a rain-water pump well level is raised during the running of (n-1) pumps and the level exceeds a n-th pump starting level, a start command is outputted to the n-th pump. Simultaneously the inflow rate is estimated from water level variation per unit time and the cross section of a pump well W. When the n-th pump P is run, the discharge valve V is slightly opened, the level of the pump well W is raised up to the full open of the discharge valve V, and the level exceeds the starting level of the (n+1)th pump, the estimated inflow rate is compared with the maximum discharge flow rate at the time of additionally starting the (n+1)th pump to determine the validity of the output of a start command. When the water level exceeds the starting level of the (n+1)th pump after fully opening the discharge valve V, a start command is outputted at that time to run the (n+1)th pump.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention is a system for controlling the number of operating pumps in a rainwater pump well having a plurality of rainwater pumps of the same capacity according to the water level of the pump well. This invention relates to a device for controlling the number of rainwater pumps to be controlled.

(Prior art) Conventionally, when controlling the number of pumps based on the water level of a rainwater pump well, when the water level exceeds the startup level, a startup command is output to one next pump to operate the pump and discharge water. The valves are opened slightly and fully open one after another, and the decision as to whether to start the next pump is made only after the previous pump that was started by the start command is operating and the discharge valve is slightly or fully open. This is done based on the new water levels in the rainwater pump wells.

FIG. 3 shows an example of the pump well water level fluctuation when the pump is started when the inflow flow rate is constant.

Figure 3 shows that when the water level exceeds the activation level of the third pump
When the start command is output to the No. 1 pump, the No. n pump starts, and the discharge valve changes from fully open to volume → fully open,
This is a case where the inflow flow rate is a constant value corresponding to the rated capacity of n pumps.

The water level change rate ΔQ2 during the period a from when the start command is output until the pump starts and reaches the discharge valve volume is the same as the water level change rate ΔQ1 before the start command is output, and the water level continues to rise.

The water level change rate ΔQ3 during the period from the discharge valve volume to the fully open state decreases as the discharge volume gradually increases, and becomes Δ+13 <ΔC2.

During period C after the discharge valve is fully opened, the water level does not rise unless the inflow flow rate increases.

(Problem to be Solved by the Invention) However, in the above conventional method, the actual pump discharge flow rate is smaller than the pump rated flow rate during the operation period from the discharge valve volume to the discharge valve fully open (b in Figure 3). Therefore, the next number control is judged during the discharge valve volume and the next machine (n+
When a start command is output to Unit 1) and it is operated, the previous unit (
The discharge valve of Unit No. n) is fully opened, the pump discharge flow reaches its maximum, and the pump well water level falls.

Further, the (n+1) abutment is subsequently fully opened due to the discharge valve volume, further lowering the water level of the pump well.

If the next number control is determined during the period from the discharge valve volume to full opening in this way, the pump well water level will drop after the discharge volume reaches its maximum value, and in particular, a start command will be output for two units in a row. Then, the water level in the pump well drops rapidly and immediately reaches the pump stop level, causing the pump that has just started to stop, resulting in the problem of unnecessary starting and stopping of the pump.

On the other hand, when there is a sudden change in the inflow flow rate, if the next unit control is not determined until the discharge valve is fully opened, the start-up of the next unit will be delayed, and the water level in the rainwater pump well will rise rapidly and reach a dangerous water level. will occur.

The present invention controls the number of pumps in consideration of the estimated inflow flow rate even during the transition period when the pump discharge valve is fully opened from the pump discharge valve volume, thereby preventing unnecessary starting and stopping of the pumps and preventing sudden fluctuations in the inflow flow rate. The purpose of this project is to provide a rational system for controlling the number of rainwater pumps.

[Structure of the invention]

(Means and effects for solving the problem) The present invention provides that when the number of rainwater pumps is controlled according to the water level of the rainwater pump well, if the number of currently operating rainwater pumps is (n-1), When the water level exceeds the nth activation level, an overtime command is output to the nth pump, and at the same time, the inflow flow rate is estimated from the rate of change in the water level of the pump well,
When the water level of the rainwater pump well exceeds the activation level of (n+1) abutment during pump operation until the discharge valve is fully opened from the nominal flow rate, the estimated inflow flow rate is greater than the total discharge flow rate after (n+1) pewter operation. When it is large, a start command is immediately output to the (n+1) pumps at the joint, and when it is small, a new decision is made to control the number of pumps after waiting for the discharge valve to fully open, thereby preventing unnecessary starting and stopping of pumps. In addition to preventing
It is designed to be able to cope with sudden increases in inflow flow rate.

(Example) An embodiment of the present invention is shown in FIG.

Fig. 1 shows the configuration of a rainwater pump well W to which the present invention is applied, including M rainwater pumps P~PM of the same capacity fQ, discharge valves V□~VM, and 1st~Mth rainwater pumps. Startup for
It is equipped with a water level gauge H that indicates the stop level.

Next, the operation of the apparatus for controlling the number of rainwater pumps according to the present invention will be explained with reference to the flowchart shown in FIG.

When (n-1) pumps are in operation, when the pump well water level rises and exceeds the nth activation level, a startup command is output to the nth pump (1).

At the same time, the inflow flow rate Qin is estimated from the water level fluctuation per unit time and the cross-sectional area A of the pump well according to the following formula.

Q. = Month of the second section of the trowel x A Δt where L(t) is the water level of the rainwater pump well at the current time t L(t-1) is the water level of the rainwater pump well at the time (t -1) Δt is the unit time A is the cross-sectional area of the rainwater pump well.

If the water level in the rainwater pump well rises between the time when the nth pump is operated and reaches the discharge valve volume, and when the discharge valve is fully opened, and exceeds the starting level of the pewter (n+1), it is calculated using the above formula. The estimated inflow flow rate Qin and the maximum discharge flow rate QwaaM when additionally starting (n+1) pewter, that is, QX(n+
1) is compared, and it is determined whether or not to output the activation command to the white of the (n+0) eyes.

In other words, when Qhn > Q-ax, the water level continues to rise even after the nth pump is fully opened, and there is a risk of a sudden rise in the water level, so a start command is immediately output to the white pump (n+1). ).

Also, when Qin≦QI11aX, there is a possibility that the water level will drop when the nth discharge valve is fully opened, and the water level rise at this time is considered to be due to a transient phenomenon, so a start command is issued to the (n+1) pewter. There is no output, and the number of units I11 is not controlled until the discharge valve is fully open.

If the water level exceeds the (n+1) pewter activation level even after the discharge valve is fully open, a start command is output for the first time at that point (the discharge valve is fully open), and the (n+1) pewter is operated.

Note that the method for estimating the inflow flow rate is not limited to the above method, and the present invention can be applied to cases where other inflow flow rate estimation methods are used.

〔Effect of the invention〕

As explained above, according to the present invention, in controlling the number of rainwater pumps based on the water level of the rainwater pump well, the inflow flow rate is predicted from the rate of change in the water level, and the predicted inflow flow rate increases the number of currently operating pumps by one. When it is determined that the discharge flow rate is larger than the discharge flow rate, the next unit is judged to start based on the discharge valve volume and a start command is output. Conversely, when the discharge flow rate is determined to be larger than the inflow flow rate, A rational system for controlling the number of rainwater pumps that waits for the start judgment until the discharge valve is fully open, thereby preventing unnecessary pump starting/stopping, and safely responding to sudden increases in inflow flow. can get.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing the operation of the present invention, and FIG. 3 is a time chart showing an example of a change in water level in a pump well when the pump is started. P1~PM...Rainwater pump V, ~VM...Discharge valve H...Water level gauge W...Rainwater pump well (
8733) Agent Patent Attorney Yoshiaki Inomata (and 1 other person)

Claims (1)

[Claims] In a rainwater pump number control device that increases or decreases the number of operating pumps in a rainwater pump well that has multiple rainwater pumps of the same capacity depending on the water level of the pump well, when the water level of the pump well exceeds the activation level, the following 1. When the first pump is started, the inflow flow rate to the pump well is estimated from the water level change in the pump well within a certain period of time at that point, and this estimated inflow flow rate is used for operation including the first pump after being started. If the flow rate is larger than the total discharge flow rate of the pump in the middle, the next second pump is started immediately, and the estimated inflow flow rate is equal to or less than the total discharge flow rate of the pumps in operation, including the first pump. A system for controlling the number of rainwater pumps, characterized in that when the discharge valve completes the operation from partially open to fully open, the number control operation is performed.