JPS60687B2 - How to adjust the water level in a tunnel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water level adjustment method for controlling the water level of a water discharge tank in water supply and sewage facilities.

Conventional water level control in water and sewage facilities involves inputting the water level of the discharge tank into an analog controller, and calculating Pm based on the deviation from a preset target water level (in some cases, there is no D operation).
), and the opening degree of the inflow valve that controls the amount of inflow into the road is controlled. However, such water level control does not take into account nonlinear elements between the water storage amount and water level, nonlinear elements between the inflow valve opening degree and the inflow amount, etc. in changes in the storage surface area due to the discharge tank water level, and therefore, the control constants are The system was controlled to be stable even in the worst case of nonlinear elements.

As a result, the reaction of the system becomes quite slow, and control may become uncontrollable when the volume of the discharge tank in the road is small, or when the road is quite long and the water introduction time delay is long. Therefore, in such a case where control is impossible, stable control cannot be achieved because a person has to predict changes in the discharge base and adjust the inlet valve. Further, even when an electronic computer is used, the calculations performed inside the PID adjuster are simply performed inside the computer, and the same drawbacks as described above still exist.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for adjusting the water level of a sushi canal that can control the water level of a sushi tank with good response and stability.

An embodiment of the present invention will be described below with reference to FIGS. 1a, b to 4.

That is, in FIG. 1a, the channel 1 has a horseshoe-shaped cross section as shown in FIG. 1b. In addition, a discharge tank 2 is provided in the sushi road 1. Reference numeral 3 denotes a flow rate regulating valve for controlling the amount of flow into the stream 1, and the opening degree of this flow rate regulating valve 3 is controlled by a drive motor 4 controlled by an arithmetic and control device 6, which will be described later.

Reference numeral 5 denotes a water level gauge for measuring the current water level in the discharge tank 2, and the output of this water level gauge 5 is input to an arithmetic and control unit 6, which will be described later. Here, the water level in the discharge tank 2 is set to the upper limit water level HWL.
, the lower limit water level is indicated by LWL, and the target water level is indicated by Lsp. On the other hand, numeral 6 denotes an arithmetic and control device to which the output of the water level gauge 5 is given, and this arithmetic and control device 6 has a curve representing the relationship between the water level L of the discharge tank and the amount of water stored in the discharge tank V as shown in FIG. 2, as shown in FIG. A characteristic curve representing the relationship between the flow rate regulating valve function 0 and the inflow amount F as shown in FIG.
The curves representing the relationship between the road water conveyance delay time t are stored as high-order functions or polygonal line approximations, and the amount of opening correction of the flow rate control valve 3 is determined by using these curves and calculations described later. I am trying to output the amount of correction.

In other words, in this case, the arithmetic and control device 6 calculates the current water storage amount Vp from the curve of FIG. 2 when the current water level of the discharge tank 2 is Lpv.
On the other hand, from the pre-stored target water level Lsp of the discharge tank 2, the target water storage amount Vsp is determined from the curve shown in FIG. Then, from the water storage amount deviation due to these Vpv and Vsp, the correction amount ΔF of the road inflow amount is obtained by subtracting from the following equation.
△F=K{(en-en-・)+T unit n+character〈en-skin, ten en-2)},. ．． 、． en: Water storage amount deviation (=Vs
p-Vpv)en-,: Value at the previous control cycle as above en-2: Value at the time before the previous control cycle as above 7: Control cycle K: Proportionality constant TI: Integral time TD: Derivative time Here, generally, The flow velocity in Hokkaido can be found from Manning's formula, Bazahn's formula, etc., but the flow velocity in Hokkaido is determined by the horseshoe-shaped drop, the drop in the road, and the flow rate F in Hokkaido as shown in Figure 1b above.
Since the relationship between the prefecture water introduction delay time t becomes a curve as shown in Figure 4, when the inflow amount F changes, the water introduction delay time t
As a result, the dead time of the water level control system changes, so the proportionality constant K in equation {1' is corrected by the following equation.

K=f(t) ……■ t: Water introduction delay time f(t): Generally a monotonically decreasing function, then calculated using the '1' formula. The flow rate control valve opening correction amount △ is determined from the characteristic curve of . First, the current inflow amount Fpv is determined from the curve in Figure 3 using the current flow rate control function pv, and using the above correction amount △F, Fpv + △F When the inflow amount Fpv is 10ΔF, the flow rate regulating valve function ◇ is similarly determined from the curve in FIG. 3, and finally the flow rate regulating valve opening correction amount Δ0 is determined from the following equation.

△Low = ○PV-Medium...{3} Then, the flow rate control valve opening correction amount △ obtained from the formula {3' is outputted to the drive motor 4 to control the valve opening of the flow rate control valve 3. I try to do that.

Next, to describe the operation of the present invention configured as above, let us say that the current water level of the discharge tank 2 of the road 1 is Lpv.
This water level Lpv is used as the output of the water level gauge 5 by the arithmetic and control unit 6.
given to.

Then, the arithmetic and control unit 6 calculates the current water storage amount Vpv from the curve shown in FIG. 2 from the current water level Lpv, and then calculates the target water storage amount Vsp from the curve shown in FIG. 2 from the previously stored target water level Lsp. From the water storage amount deviation due to Vpv and Vsp, the correction amount of road inflow △F is removed from equation (1).
is required. In this case, the cross section of the road 1 has a horseshoe shape as shown in Fig. 1b, and the relationship between the flow rate F in the road 1 and the water introduction delay time t in the road 1 is shown in Fig. 4. Since it becomes as follows, the proportionality constant K in the equation {1- is (2}
Modified by Eq.

Then, the opening correction amount △◇ of the flow rate control valve 3 is determined from the correction amount △F obtained from equation {1) and the characteristic curve in FIG. The current inflow amount Fpv is obtained from the curve in the figure, Fpv+△F is calculated using the above correction amount △F, and then this inflow amount Fp
From v+ΔF, the flow rate regulating valve opening degree 0 is determined from the curve in FIG. 3, and finally, the flow rate regulating valve opening degree correction amount Δmedium is determined from the control formula.

Therefore, the output corresponding to this correction amount △0' is the output from the arithmetic and control unit 6.
This is applied to the drive motor 4 to control the valve opening of the flow rate regulating valve 3, thereby controlling the water level in the discharge tank 2 toward a preset target water level Lsp. According to such a configuration, the basic control calculation is performed using only the water storage amount deviation according to equation [1], and there is no need to adjust the control constants for any target water level, resulting in a good response. can be controlled.

In addition, the gain of the control formula is automatically adjusted by taking into consideration changes in the water introduction delay time due to the flow rate in Hokkaido, so responsive control can be performed without having to adjust control constants for any inflow amount. Can be done. Furthermore, since the characteristic curve of the valve is utilized when converting the inflow amount correction amount into the flow rate regulating valve function correction amount, responsive control can be performed at any valve function. Therefore, the water level in the road discharge tank can be stably controlled without using so-called adaptive control which has the same characteristics and provides the best response under all conditions. Note that formula [1} in the above embodiment is based on general DDC control calculation, but the present invention is characterized in that control calculation is performed using the water storage amount deviation, and various other methods can be used. Even when the control calculation formula is used in place of formula (1), the same effect can be achieved by using the water storage amount deviation instead of the water level deviation.

In addition, the gain of the control calculation formula is automatically corrected based on the prefecture water introduction delay time, and the valve opening correction amount is obtained by taking into account the inflow amount correction amount and the characteristics of the flow rate control valve. However, even if only some of these are used, considerable effects can be expected compared to the conventional techniques. Furthermore, although an arithmetic and control unit is used in the above-described embodiment, it is also possible to construct the present system by combining a general function generator, an analog regulator, etc. Furthermore, in the above embodiment, a telemeter/telecontrol device is not provided for simplicity, but if the flow rate control valve and discharge tank are located far apart, a telemeter/telecontrol device can of course be used. It will be configured.

In addition, it goes without saying that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with appropriate modifications without changing the gist.

[Brief explanation of the drawing]

1a and 1b show an embodiment of the method for adjusting the water level in a waterway according to the present invention, FIG. 1a is a block diagram of an apparatus for implementing the method, and FIG. 1b is a 2 to 4 show the memory curves of the arithmetic and control unit applied to the same embodiment, and FIG. 2 shows the discharge tank water level L and the amount of water stored in the discharge tank. Figure 3 is a curve diagram representing the relationship between the flow rate control valve opening degree 0 and the inflow amount F, and Figure 4 is a curve diagram representing the relationship between the inflow amount F and the water transfer delay time t. It is a diagram. 1... Sushi, road, 2... Discharge tank, 3.
...'Flow control valve, 4...Motor, 5...
...・Water level gauge, 6.... Arithmetic control device. Mena M Meku @ Mezo ■ Meku moth

Claims (1)

[Claims] 1. In a method of adjusting the water level of a channel discharge tank by operating a channel flow rate regulating valve, a first curve representing the relationship between the discharge tank water level and the amount of water stored in the discharge tank is defined in advance. A second curve representing the relationship between the opening degree of the inflow control valve and the tunnel inflow amount, a third curve representing the relationship between the tunnel inflow amount and the tunnel water introduction delay time, and calculation for calculating the correction amount ΔF of the tunnel inflow amount. Formula ΔF=K{(en-en_-_1)+τ/(Τ_
I) en+(TD)/τ(en-2en_-_1+en
____2)} However, en: Water storage amount deviation en_-_1: Value at the previous control cycle same as above en_-_2
: Value τ at the time of the control cycle before the previous same as above: Control cycle K: Proportionality constant T_I: Integral time T_D: Derivative time, find the water storage amount deviation from the current water level and target water level of the discharge tank using the first curve, Using this in the above formula and taking into account the change in water introduction delay time due to the flow rate in the tunnel from the third curve, calculating the correction amount ΔF of the tunnel inflow amount while adjusting the proportionality constant in the above formula, and calculating the correction amount ΔF and a method for adjusting the water level of a channel, wherein the opening degree of the flow rate regulating valve is controlled using the second curve based on the current opening degree of the flow rate regulating valve.