JPH0747350A - Controller for sewage treatment plant - Google Patents

Abstract

PURPOSE:To carefully control various equipments in a sewage treatment plant according to the time of fine or rainy weather. CONSTITUTION:A waste water inflow rate estimation means 3 for estimating the waste water inflow rate to a pump well 16 based on a change in the water level of the pump well 16 during a prescribed period of time and on the discharge of a sewage pump 18 during the period, and a wavelet conversion means 4 for giving wavelet conversion to the estimated value from the waste water inflow estimation means 3 are provided. Based on a signal from the wavelet conversion means 4, a weather judgement means 5 determines whether it is fine or rainy. Based on the result from the weather judgement means 5, a control system selective means 7 gives a choice between a fine weather controller 9a and a rainy weather controller 9b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage treatment plant control device for automatically controlling various devices provided in a sewage treatment plant.

[0002]

2. Description of the Related Art Generally, a sewage treatment plant is provided with a pump well, and a plurality of sewage pumps are installed on the outlet side of the pump well. Wastewater such as rainwater and sewage introduced into the pump well through the buried pipe is discharged by this sewage pump and sent to the subsequent process.

Conventionally, a sewage pump in such a sewage treatment plant is controlled by a controller. In this case, regardless of whether it is fine weather or rainy weather, the controller controls the amount of drainage by switching the number of sewage pumps operating based on the level of the water level in the pump well.

[0004]

However, such a conventional control device for a sewage pump has the following problems.

Generally, the purpose of operation of a sewage pump in a sewage treatment plant is to promptly discharge the drainage of rainwater, sewage, etc., which has flowed into a pump well through a buried pipe. The amount of inflow into the pump well during fine weather largely depends on human activity, and the inflow can be predicted in advance to control the sewage pump. On the other hand, it is difficult to predict the inflow because it depends on a natural phenomenon when it rains.

[0006] As described above, the characteristics of the inflow into the pump well greatly change in fine weather and in rainy weather, whereas in the past, the operation of the sewage pump depends on whether the water level in the pump well is high or low, regardless of the weather. Since the number of units is changed, detailed control cannot be performed. As a result, the number of sewage pumps operating in the pump well may fluctuate drastically, and each sewage pump may be frequently turned on and off to make the operation of the sewage treatment plant unstable. Further, there is a problem in that the followability of the operation of the sewage pump is poor in rainy weather and the load on the secondary treatment system is increased.

The present invention has been made in consideration of such a point, and the number of operating sewage pumps fluctuates drastically or each sewage pump is frequently turned on and off regardless of whether it is fine weather or rainy weather. It is an object of the present invention to provide a control device for a sewage treatment plant, which can perform detailed control for reducing the load on the secondary treatment system without causing any waste.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a sewage pump installed in a pump well into which drainage flows, and various equipment,
In a control device of a sewage treatment plant comprising, a fine weather control system for controlling the equipment of the sewage treatment plant during fine weather, a rainy weather control system for controlling the equipment during rainy weather, and the water level of the pump well within a predetermined period. Based on the change and the discharge flow rate of the sewage pump during this period, a wastewater inflow amount estimating means for estimating the wastewater inflow amount to the pump well, and a wavelet transform for wavelet transforming the estimated value from the wastewater inflow amount estimating means. Means, a weather determining means for determining whether the weather is fine or rainy based on the signal from the wavelet transforming means, and either the fine weather control system or the rainy weather control system is selected based on the determination result from the weather determining means. A control device for a sewage treatment plant, comprising: a control system selecting means.

[0009]

[Operation] In the drainage inflow estimation means, the drainage inflow into the pump well is estimated based on the change in the water level of the pump well within the predetermined period and the discharge flow rate of the sewage pump during this period. The estimated value of is wavelet transformed by the wavelet transformation means. Based on the signal from the wavelet transforming means, the weather determining means causes clear weather /
Rainy weather is judged. The control system selection means selects either the fine weather control system or the rainy weather control system based on the determination result from the weather determination means.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a control device for a sewage treatment plant according to the present invention. In FIG. 1, the sewage pump 18 provided in the sewage treatment process 1 is a control device 2
It is controlled by.

Next, the sewage treatment process will be described in detail.

The sewage treatment process 1 comprises a sand basin 13 having an inflow gate 14 installed therein, and a pump well 16 provided continuously to the sand basin 13. An inflow gate water level gauge 15 is provided near the inflow gate 14, and a pump well water level gauge 17 is provided in the pump well 16.
Furthermore, a sewage pump 18 is installed in the pump well 16,
A pump flow meter 19 that measures the discharge flow rate of the sewage pump 18 is provided on the discharge side of the sewage pump 18.
Further, the sewage treatment process 1 is provided with a rain gauge 12.

A rain gauge 12, an inflow gate water level gauge 15,
The process quantity is sent from the pump well water level meter 17 and the pump flow meter 19 to the process interface 10 of the control device 2, and the process interface 10 side of the control device 2 pumps the sewage pump 18 such as the number of operating units and the target speed value. A control command is given.

On the other hand, the control device 2 estimates the amount of drainage inflow to the pump well 16 based on the change in the water level of the pump well 16 within a predetermined period and the discharge flow rate of the sewage pump 18 during this period. Means 3, wavelet transforming means 4 for wavelet transforming the estimated value from the wastewater inflow estimation means 3, weather determining means 5 for determining the current weather from the signal from the wavelet transforming means 4, and weather determining means 5
And a control system selecting means 7 for selecting a pump control system from a signal from the operator or a signal input from the operator 6 through the man-machine interface 8.

Further, the control device 2 has a pump control section 9 comprising a fine weather pump control system 9a selected by the control system selecting means 7 and a rainy weather pump control system 9b. Of these, the fine weather pump control system 9a is a sewage pump 1 during fine weather.
8 and the rainwater pump control system 9b controls the sewage pump 18 in rainy weather.

The control device 2 also has a man-machine interface 8 that interfaces with the operator as described above, and a process interface 10 that interfaces with the sewage treatment process 1.

Next, the operation of this embodiment having such a configuration will be described. First, based on the water level of the pump well 16 obtained from the signal from the pump well water level meter 17 and the discharge flow rate of the sewage pump 18 obtained from the signal from the pump flow meter 19, the waste water inflow estimation means 3 at time t. The drainage inflow quantity q (t) into the pump well 16 is estimated by the following equation.

[0019]

[Equation 1] Here, q (t): drainage inflow amount Ls (t): pump well water level qs (t): pump discharge flow rate f: conversion function from pump well water level to storage capacity Δt: calculation cycle Next, in the wavelet transform means 4. The inflow quantity q (t) estimated by the wastewater inflow quantity estimating means 3 is wavelet transformed. Output T (a, from the wavelet transformation means 4 when the wastewater inflow amount q (t) is wavelet transformed
b) is as follows.

[0020]

[Equation 2] Here, a: scale parameter b: shift parameter φ: wavelet function Note that the wavelet function satisfies the following conditions.

[0021]

[Equation 3] Examples of functions that satisfy such conditions include the following Mexican Hat function.

[0022]

[Equation 4] In the wavelet transform in the wavelet transform means 4, the parameters a and b are changed as follows.
First, the shift parameter b is moved in parallel on the time axis to find the time when the change occurs. Further, the scale parameter a is compressed or expanded on the time axis to change the time for finding the change. That is, the scale parameter a is expanded to find a gentle change, and the scale parameter a is compressed to find a sharp change.

Next, the weather determining means 5 determines the current weather (clear weather / rainy weather) based on the output T (a, b) of the wavelet transforming means 4. In this case, by inputting the judgment knowledge of the operator 6 into the weather judgment means 5,
It is possible to more reliably determine the weather.

Next, the determination operation of the weather determination means 5 will be described. The output T (a, b) of the wavelet transform takes a large value at the discontinuous point of the wastewater inflow amount q (t). When the weather changes from clear weather to rainy weather, the wastewater inflow q (t) becomes discontinuous. Therefore, the weather (clear / rainy) can be easily determined by wavelet transforming the wastewater inflow q (t). You can

Next, in the control system selecting means 7, on the basis of the judgment result of the weather (clear weather / rainy weather) obtained by the weather judging means 5, for the clear weather pump control system 9a built in the pump controller 9 and for the rainy weather. Which of the pump control systems 9b is used is selected. Next, the sewage pump 18 is controlled by the fine weather pump control system 9a or the rainy weather pump control system 9b selected by the control system selecting means 7.

As described above, according to this embodiment, it is possible to finely control the sewage pumps in fine weather or in rainy weather, so that the number of sewage pumps operating suddenly changes or the The cutting is not done frequently.

The present invention is not limited to pump operation control. For example, when performing DO control on the blower of the aeration tank of the sewage treatment process, a DO control system for fine weather / rainy weather may be built in the DO control unit of the blower. In this case, based on the judgment result from the weather judging means 5,
The control system selecting means 7 selects a DO control system for fine weather or a DO control system for rain. In this way, fine DO control of the aeration tank can be performed, and abrupt changes in the number of operating blowers and frequent on / off switching can be prevented.

[0028]

As described above, according to the present invention,
It is possible to finely control various equipment in the sewage treatment plant in fine weather or rainy weather. For this reason, the number of operating various devices to be controlled does not change suddenly, and switching on / off does not occur frequently.

[Brief description of drawings]

FIG. 1 is a schematic system diagram showing an embodiment of a control device for a sewage treatment plant according to the present invention.

[Explanation of symbols]

 1 Sewage treatment process 2 Control device 3 Inflow amount estimation means 4 Wavelet transformation means 5 Weather determination means 7 Control system selection means 9a Fine weather pump control system 9b Rainy weather pump control system

Claims (2)

[Claims] 1. A control system for a sewage treatment plant, comprising a sewage pump installed in a pump well into which waste water flows and various devices, comprising: a fine weather control system for controlling the sewage treatment plant devices during fine weather. And a control system for rainwater that controls the equipment in rainy weather, a change in water level of the pump well within a predetermined period, and the discharge flow rate of the sewage pump based on the discharge flow rate of the sewage pump during this period Wastewater inflow amount estimating means, wavelet transforming means for wavelet transforming the estimated value from the wastewater inflow estimating means, weather judging means for judging whether the weather is fine or rainy based on the signal from the wavelet converting means, and this weather judging A control device for a sewage treatment plant, comprising: a control system selecting means for selecting either a fine weather control system or a rainy weather control system based on a determination result from the means. 2. The control device for a sewage treatment plant, wherein the device controlled by the control system for fine weather or the control system for rainy weather is a sewage pump installed in a pump well.