JPS6226506A - Pump operation control device - Google Patents

Abstract

PURPOSE:To reduce a variation of a liquid level by forecasting a pump well inflow flow rate from a liquid level of a pump well and a discharge flow rate of a pump, and determining automatically a parameter of a pump well liquid level controller therefrom. CONSTITUTION:A pump operation control device is constituted of a pump well liquid level controller 1, an object process 4 consisting of a pump 2 and a pump well 3, an inflow flow rate forecasting means 5, a controller parameter determining means 6, a discharge flow rate determining means 7, and a pump well liquid level measuring instrument 8. A discharge flow rate (q) of this pump 2 and a liquid level (h) of the pump well 3 are measured, and the respective measured values q', h' are inputted to the inflow flow rate forecasting means 5. By using this value and the past value, a forecasting value (qi) of an inflow flow rate in the next control period is calculated, and also a peak value set value and an attenuation coefficient of an indicial response of a liquid level to the inflow flow rate are set, based on which a value of a controller parameter is calculated. By this parameter, a pump discharge flow rate set value is calculated by the liquid level set value and the liquid level measured value h', and the pump 2 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a pump operation control device that automatically controls the liquid level in a pump chamber.

[Technical background of the invention and problems in the background art] Generally,
The pump pumps up the liquid stored in the pump chamber. Pump discharge, which is the amount of water pumped, is often controlled according to the pump liquid level to avoid overflowing or drying up the pump. In that case, the problem is the inflow flow rate to the pump. If this inflow flow rate is constant, known, or measurable, it is not a problem, but for example, at a pumping station in a water and sewage facility, the inflow flow rate is a disturbance to the liquid level control of the pump, and this is caused by uncontrollable factors such as weather. etc., and it cannot be directly measured. Therefore, a method has already been considered to control the liquid level by predicting the inflow flow rate based on the past and present liquid level fluctuations in the pump (IEE of Japan/Industrial Power Application Study Group material [Dynamic semi-optimal of sewage and rainwater pumps] "Driving Law" document number IA-81-6 (1981-1-29)).

However, in this method, since the water level control parameters are fixed, large liquid level fluctuations occur due to prediction errors, unexpected disturbances, etc., and even larger fluctuations in the discharge amount may occur.

[Purpose of the invention]

The purpose of this invention is to automatically adjust the parameters of the liquid level controller to solve the above problems, and to perform liquid level control that is stable against unexpected fluctuations in the inflow flow rate and has small liquid level fluctuations. An object of the present invention is to provide a pump operation control device that can perform the following steps.

[Summary of the invention]

As shown in FIG. 1, the pump operation control device of the present invention has the following features:
In the pump/pump cell system that is the target process, the pump discharge flow rate is directly or indirectly measured to obtain the discharge flow rate measurement value q', and the pump cell liquid level is measured by the pump cell liquid level measuring device 8. The value h' is input to the inflow flow rate prediction means 5, and as a result, the inflow flow m prediction fiflq+ is outputted, and based on this inflow flow dumpling measurement value q1, the controller parameter determination means 6 determines the controller parameters, T, By setting the pump volume level controller 211 1, the liquid level of the pump volume is controlled in the next control cycle.

[Embodiments of the invention]

The pump operation control device according to the present invention is suitable for water supply and sewage, industrial water, irrigation, etc. As an example, the case where it is applied to a pumping station in a sewage treatment plant, not shown in FIG. 3, will be considered below.

In FIG. 3, reference numeral 3 denotes a pump chamber, and a pump 2 is installed to pump up rainwater and sewage flowing into the chamber. In pumping stations, pumps are usually of different capacities,
There are multiple units with different formats, but in this example,
The following description assumes that there is only one of these. In particular, when there are multiple pumps of the same type, it is sufficient to use the same controller for all pumps, and even when there are multiple pumps of different types, the principles of the present invention can be easily inferred.

The signal of the pump chamber liquid level measuring device 8 attached to the pump chamber 12 and the signal of the discharge flow determination means 7 which determines the discharge flow rate of the pump 2 are sent to the electronic computer 16, and the pump chamber liquid level setting value href is taken into consideration. This is to operate the rotation speed setting value vref of the electric motor 13, which is the prime mover of the pump.

For example, a discharge flowmeter can be used as the discharge Fffi determination means 7.

FIG. 1 shows the internal calculation structure of the electronic computer 16.

In FIG. 1, 4 is the target process, which includes pump 2 and pump mass 3. The liquid level control of the pump cell takes as input the pump cell liquid level set value href and the pump cell liquid level measurement value h' and outputs the pump discharge flow opening set value qref. In the controller parameters of the controller, T is the discharge flow ff1i
Inflow flow rate prediction means △ by inputting + measured value q' and pump liquid level measured value h'.

Based on the inflow dumpling measurement value q1 outputted by 5, f
, is determined by the device parameter determining means 6.

In this embodiment, PI control is considered as the pump liquid level controller 1. At this time, the configuration of the controller parameter determining means 6 is as follows.

FIG. 4 is a block diagram regarding the pump liquid level. Considering the pump mass liquid level controller transfer function block 21, pump discharge flow rate transfer function block 22, and pump mass liquid level transfer function block 23 as shown in the figure, the pump mass liquid level for a displacement Δq1 of the inflow flow rate which is a disturbance The transfer function H(S) for the displacement Δh is 1・S ・・・・・・・・・(1) (However, A: Pump cross-sectional area −, : Controller parameter ■・: S Nilaplus Operator ), which can be expressed in the form S2+2・ζ・ω・S+ω2 nn.

Since the individual response f(t) is given by t: time, if t is t that satisfies 10, then tanθ=□, and in this case, the fluctuation of the pump liquid level due to disturbance is as shown in Figure 5. reaching a peak. Peak value f at this time
(t,) becomes. Equation (7) is K using equation (3).

From this, it can be seen that the peak value f(tp) of the individual response of the pump liquid level due to disturbance depends on the controller parameters and the damping coefficient of the system.

Therefore, in order to suppress to some extent the fluctuation in the pump cell liquid level due to the fluctuation in the inflow flow rate, which is a disturbance to the pump cell, the present invention is based on the assumption that the fluctuation a in the inflow flow m is proportional to the value of the inflow flow rate, and then the attenuation is performed. By fixing the coefficient ζ and using the peak value f(tp) of the individual response of the pump mass liquid level to a preset inflow flow rate, the controller parameters are:
This is what determines the Therefore, f(t,) is determined based on the predicted inflow flow rate q1.

Next, a series of operations of the pump operation control device configured as described above will be explained.

FIG. 2 shows the operations performed inside the electronic computer 16. Operation 9 is performed every υ control period.

Pump liquid level and pump discharge flow rate q at a certain time
, and input the pump liquid level measurement value h' and the pump discharge flow rate measurement value q'. Next, use these values and these past values to perform the next control △.

Calculate the predicted value q+ between inflows in a period. Furthermore, the peak value set value f(tp) and damping coefficient of the individual response of the liquid level with respect to the inflow flow are set, and the controller parameters are set based on these.

Calculate the value of T. Then, pump liquid level setting fI
Input ihref and use the previously input pump liquid level S1 measured value h' to set the pump discharge flow rate set value qref
is calculated, and the rotation speed of the pump motor 13 is controlled to match this.

Peak fluctuations in pumping liquid level can be suppressed.

The main focus of the present invention is to make the controller parameters Kp, T variable based on the predicted inflow flow rate value qi instead of being fixed, and other embodiments such as the following can be easily implemented. .

i) In this embodiment, an electric motor whose rotation speed can be controlled is considered, but the present invention is not limited to this, and the present invention can be applied to any pump whose flow rate can be varied.

11) In this embodiment, the prediction between the inflow flows is performed in the same cycle W1 as the controller parameter calculation, but the prediction of the inflow flow rate also depends on the fluctuations between the inflow flows, so this is not the case.

1ii) Although the controller parameter KI) is calculated using the indigine response peak value f(tp) of the pump mass liquid level based on the predicted value qi of the inflow flow rate, it is prohibited to unnecessarily increase the controller parameter Kp. In order to eliminate disadvantages in system stability due to
It is also possible to impose constraints on the determination.

iv) Pump liquid level control 1IIl device can be applied not only to PI control but also to PID control, I-PIIJtll, etc. The parameter determination method can also be easily considered by analogy with this embodiment.

(Effects of the Invention) As described above, according to the present invention, even if a prediction error or unexpected fluctuation occurs between inflows, the parameters of the controller are not fixed and are automatically adjusted, so the stability is maintained. Pump liquid level fluctuations can be suppressed.

On the contrary, it is also possible to suppress fluctuations in the pump discharge it that cause disturbances to downstream processes, and it is possible to eliminate the drawbacks caused by fixing the parameters of the υJtII device.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the functional configuration of the present invention, Fig. 2 is a diagram showing the flow of operation of the present invention, and Fig. 3 is a diagram showing the flow of operation of the present invention.
FIG. 4 is a block diagram of the pump mass liquid level, and FIG. 5 is a diagram of the pump mass liquid level individual response to the inflow flow. 1...Pump liquid level controller, 2...Pump, 3
... Pump, 5... Inflow flow rate prediction means, 6...
- Controller parameter determining means, 7'...Discharge flow rate determining means, 8...Pump liquid level measuring device, 13...Electric motor, 16...Electronic computer. ξ Fig. 2

Claims (1)

[Scope of Claims] A pump mass level controller for controlling the liquid level of the pump mass; a pump mass level measuring device for measuring the liquid level of the pump mass; and a pump fluid level measuring device for directly or indirectly measuring the discharge flow rate of the pump. pump mass inflow flow rate prediction means for predicting the pump mass inflow flow rate using the outputs of the pump mass liquid level measuring device and the discharge flow rate measurement means; and controller parameter determination means for automatically determining parameters of the pump liquid level controller by inputting the estimated inflow flow rate.