JPS62281001A - Pump operation control device - Google Patents

Abstract

PURPOSE:To attain suppression, and a stable control for the fluctuating quantity of the liquid level of a pump well, by forecasting the change quantity of an inflow discharge to the pump well based on a measured data for an outflow discharge from a pump, and the measured data for the liquid level of the pump well, and adjusting the control parameter of a liquid level control means based on the change quantity of the inflow discharge to the pump well. CONSTITUTION:First of all, the size of the forecasting value DELTAqi of the change quantity of the inflow discharge forecasted by an inflow discharge change quantity forecasting means 5 is limited by a DELTAqi limiter 21. Next, at a omegac calculating block 22, a crossed axes angle frequency omegac is calculated by using an inflow discharge change quantity forecasting value DELTAq'i after a processing by the limiter, a constant hc, a control cycle tau, and a stationary speed deviation specified value ex. Next, a crossed axes angle frequency omega'c in which the upper and lower limit of the crossed axes angle frequency omegac is limited by a omegac limiter 23, is obtained. Following that, a a Kp and Ti calculating block 24, control parameters Kp, and Ti are calculated by substituting the crossed axes angle frequency omegac after the processing by the limiter, the constant hc, and a pump well cross section A.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention is intended to improve the liquid level of pumps in pumping stations for water supply and sewerage, T9 water, irrigation, etc. The present invention relates to a pump operation control device that performs control.

(Conventional technology) In sewage treatment, when pumping the stored liquid, the pump discharge flow rate must be adjusted to avoid overflowing or drying up the pump. In this case, the problem is the amount of change in the flow rate of the inflow to the pump.In other words, the amount of change in flow rate of the inflow is a disturbance from the viewpoint of liquid level control in the pump. This is because it fluctuates greatly due to uncontrollable factors such as the weather, but cannot be directly measured.

One way to deal with this is, for example, the Institute of Electrical Engineers of Japan/Sangyo Mino] Applied Research Group Material IA-81-6 (1981
As shown in 1-29), there is a system that controls the liquid level by predicting the inflow flow rate from past and current liquid level fluctuations in the pump.

(Problems to be Solved by the Invention) However, the above control method may not be able to cope with sudden changes in the inflow flow rate because the parameters of the liquid level control system are fixed.

In other words, at the pumping station of a sewage treatment plant, the amount of sewage pumped by the pump is also the supply m for the treatment process, but in response to the request to reduce fluctuations in this supply amount, the pump plays the role of a sewage buffer. It turns out. Therefore, the response of the liquid level control system is often lowered for clear weather openings.

At this time, if the response of the liquid level control system is lowered too much, the pump inflow flow ω will increase rapidly at the beginning of heavy rain, and the liquid level control will become unstable, and the pump may become unstable. There were times when it overflowed.

The present invention was made in order to solve the above problems, and it is possible to stabilize the liquid level in the pump chamber and suppress the amount of fluctuation, and moreover, fluctuations in the pump discharge flow rate that cause disturbance to downstream processes. The purpose of the present invention is to provide a pump operation control device that can suppress the

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a liquid level measuring means for measuring the liquid level of a pump cell, and a deviation between the liquid level measurement value of the liquid level measuring means and the liquid level set value of the pump cell. a liquid level control means for controlling the pump such that the liquid level becomes zero, a discharge flow rate measuring means for measuring the discharge flow rate of the pump, and a discharge flow rate measurement value of the discharge flow rate measuring means and a liquid level measurement of the liquid level measuring means. an inflow flow rate change amount prediction means for predicting the inflow flow rate change amount of the pump based on the value; and control parameter adjusting means for adjusting.

(Function) In the present invention, when the inflow flow rate change amount predicting means predicts the inflow flow rate change amount of the pump based on the measured value of the discharge flow rate of the pump and the measured value of the liquid level in the pump chamber, the amount of change in the inflow flow rate is Based on this, the control parameter adjustment means adjusts the control parameters of the liquid level control means, thereby making it possible to suppress liquid level fluctuations in the pump basin and achieve stable control.
There is C.

(Example) Hereinafter, a case where an example of the present invention is applied to a pumping station of a sewage treatment plant shown in FIG. 2 will be described.

In FIG. 2, rainwater and sewage flow into the pump chamber 3. A pump 2 is provided to pump up this rainwater and sewage. In a pumping station, a plurality of pumps of different capacities and types are usually installed, but in this example, the description will be made assuming that there is only one pump. especially,
If there are multiple pumps of the same type, the same control means for all pumps may be used.If there are multiple pumps of different types, the principles of the present invention may be used. good.

On the other hand, the discharge side of the pump 2 is provided with a discharge flow rate measuring means 7 for measuring the discharge flow rate, and the pump chamber 3 is equipped with a liquid level measuring means 8 for measuring the liquid level. Each measured value is sent to an electronic computer 16, and the electronic computer 16 further controls an electric motor 13, which is the electric motor of the pump.

Note that, for example, a discharge flowmeter can be used as the discharge flow rate measuring means 7, and a water level measuring device can be used as the liquid level measuring means 8.

FIG. 1 is a block diagram showing the main functions of the electronic computer 16 in blocks and showing the overall configuration of the pump operation control device. In the same figure, pump 2 and pump 3
is the controlled process 4, the discharge flow rate of the pump 2 is measured by the discharge flow rate measuring means 7, and the liquid level of the pump cell 3 is measured by the liquid level measuring means 8, as described above.

Then, the liquid level measurement value h' of the liquid level measuring means 8 and the liquid level set value hrcf of the pump 13 are input, and the liquid level control means 1 controls the pump 2 so as to make the deviation between the two zero. We are prepared. Further, the discharge flow rate measurement value q of the discharge flow rate measuring means 7
' and a liquid level measurement value h' of the liquid level measuring means 8 are inputted, and an inflow flow rate change amount predicting means 5 is provided for calculating the inflow flow rate change amount ΔQi of the pump MAZU-3 from these values. Furthermore, a control parameter adjusting means 6 is provided for adjusting Ti as a control parameter of the liquid level control means 1 based on the amount of change in the inflow flow.

The electronic computer 16 has the functions of the liquid level control means 1, the inflow flow rate variation prediction means 5, and the control parameter adjustment means 6 referred to herein.

Hereinafter, the steps in this example (1) are shown in Figures 3 to 5.
3. Firstly, assuming that the liquid level control means 1 is performing PI control, this control system will be explained with reference to the drawings. As shown in FIG. , pump discharge flow rate transfer function b [1
Tsuku 12A3 and pump liquid level transfer function block 13
You can think about it. However, this control system is a -C2 type system with respect to the target value, but the steady-state deviation caused by the disturbance q is as shown in the following (1) and (2). It can be seen that there is a steady deviation for the ramp-shaped disturbance qj.

Steady position deviation e: e = 0...(
1) Sdp Sdp However, ■ represents the slope of the lamp.

By the way, the liquid level control in this embodiment is based on the steady speed deviation e
Focusing on this, the inflow flow rate change is adjusted according to the predicted value so that the dv value of the steady speed deviation e, dv is constant.
Crossing angular frequency ω of the liquid level control system. , T, are automatically adjusted in the control parameters of the liquid level control means 1 in order to change . Therefore, in the control parameter, T
The method for determining , will be explained below.

Now, the response of the pump discharge flow rate is sufficiently fast, and the transfer function of the pump discharge flow rate transfer function block 12 in FIG. 3 is 1 and d3.
shall be carried out. It is also assumed that the gain-phase diagram of the liquid level control system is as shown in FIG.

Here, the control parameters include the crossing angular frequency ω of the loop system between ,1−, and. is related to the following formula.

However, A is the cross-sectional area of the pump cell. Among these, assuming that the crossing angular frequency ω and the time constant T are always in the following relationship, the fill control parameter , Ti can be determined as follows.

Next, the crossing angular frequency ω. is determined by the following Jz.

Now, assuming that the inflow flow rate is increasing at a constant rate, the control period is τ, and the predicted value of the inflow flow rate change in the control period is Δ row, the steady speed deviation shown by equation (2) e, d
V is expressed as follows.

In the first step of keeping the steady speed deviation esdv constant, the crossing angular frequency ω is determined using the specified value ex of the steady speed deviation esdv. You can choose as follows.

(8) In reality, the crossing angular frequency ω depends on the magnitude of the predicted change value Δq· of the inflow flow rate or the value of the specified value ex of the steady speed deviation. Since the value of becomes large, stability deteriorates when sampling control is performed.

Also, the crossing angular frequency ω. Even if it is made too small, the water level deviation due to step disturbance becomes large, resulting in poor responsiveness. Therefore, the crossing angular frequency ω. In order to vary within a desired range, the predicted inflow flow rate change amount ΔQ in equation (8) must be
While limiting the magnitude of i, the crossing angular frequency ω. It is best to limit its size.

FIG. 5 shows the liquid level control parameter K mentioned above.

This figure shows the procedure for determining T. In FIG. 5, first, the Δqi limiter 21 limits the harshness of the predicted value Δq of the inflow flow rate change predicted by the inflow flow rate change amount predicting means 5. Next, ω. In calculation block 22, the intersection of the liquid level control system shown in FIGS. 3 and 4 is calculated using the predicted value of change in inflow flow rate after limiter processing Δ direction/constant hc, control period τ, and steady speed deviation specified value ex. Angular frequency ω. sieve. Next, this crossing angular frequency ω. Against ω. Limiter 2
Crossing angle frequency with upper and lower limits limited by 3. get. Subsequently, in the K, , Ti calculation block 24, the crossing angular frequency ω after limiter processing is calculated as a constant. By substituting the pump mass cross-sectional area A into equations (5) and (6), the control parameter ,T is calculated.

This control parameter, T, is determined every control period τ.

Thus, according to this embodiment, the inflow flow has a predicted change value Δ
Based on the control parameters K, T・l
By changing pl, the response of the water level control system can be changed in accordance with fluctuations in the inflow flow rate, so stable control can be performed in conjunction with control that suppresses the amount of fluctuation in the liquid level.

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

Furthermore, in the embodiment described above, the prediction of the amount of change in the inflow flow rate and the calculation of the control parameters are performed synchronously, but the prediction of the amount of change in the inflow flow rate also depends on fluctuations in the inflow flow rate, and is not limited to this.

Furthermore, in the above embodiment, the control parameter adjusting means having two limiters was explained, but this is merely an example, and the number and limiting method are not limited to this. To improve sex,
to the control parameters.

An absolute value limiter or a variation limiter may also be used for Ti itself.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the control parameter T is adjusted depending on fluctuations in the flow rate flowing into the pump cell, so it is stable regardless of the weather. , and control that suppresses the amount of liquid level fluctuation can be performed.

Furthermore, it is possible to suppress fluctuations in the discharge flow rate of the pump, which may cause disturbances to downstream processes, and it is possible to eliminate the drawbacks of conventional devices caused by fixed control parameters.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a block diagram showing the schematic structure of the embodiment, and Fig. 3 is a transfer function block diagram for explaining the operation of the embodiment. ,
FIG. 4 is a gain-phase diagram for explaining the operation of the embodiment, and FIG. 5 is a functional block diagram showing the detailed configuration of the main elements of the embodiment. DESCRIPTION OF SYMBOLS 1... Liquid level control means, 2... Pump, 3... Pump mass, 5... Inflow flow rate variation prediction means, 6... Control parameter adjustment means, 7... Discharge flow rate measuring means , 8
...Liquid level measuring means, 9...Electric motor, 10...Electronic computer.

Claims (1)

[Scope of Claims] 1. A liquid level measuring means for measuring the liquid level of the pump cell, and a liquid level measuring means for measuring the liquid level of the pump cell, such that the deviation between the liquid level measurement value of the liquid level measuring means and the liquid level set value of the pump cell becomes zero. a liquid level control means for controlling the pump; a discharge flow rate measuring means for measuring the discharge flow rate of the pump; and a discharge flow rate measuring means for measuring the discharge flow rate of the pump; an inflow flow rate change amount prediction means for predicting an inflow flow rate change amount of the trout, and a control parameter adjustment means for adjusting a control parameter of the liquid level control means based on a predicted value of an inflow flow rate change amount of the inflow flow rate change amount prediction means. A pump operation control device characterized by comprising: 2. When the liquid level control means performs a PI adjustment operation, the control parameter adjustment means adjusts the control parameters of the liquid level control means so that a steady speed deviation with respect to the liquid level of the pump chamber is constant. A pump operation control device according to claim 1.