JPS5941016A - Method for controlling water level of water channel system - Google Patents

Abstract

PURPOSE:To keep the water level of a water channel system within a permitted range with a simple circuit configuration by operating the compensating value of discharged flow rate on the basis of the variation of the water level during the sampling period and compensating the discharged flow rate on the basis of the compensating value. CONSTITUTION:An transmission element 15 indicates the transmissibility of a water channel part consisting of a driving channel 2, a head tank 1, and a discharging channel 4 and includes a delay element 8, constant elements 9, 14a, an integration element 11, adding points 10, 12, and a control element 16. The element 16 controls the outflow rate Q of the water channel system and includes an outflow rate controlling element 18, a sampler 20, a holding element 19, etc. An adding point 17 compares the value indicated by a water level setting command ho with the real value h to find the water level deviation and supplies the deviation to the element 18. The element 18 finds the discharged volume compensating value from the variation of the water level during the sampling period to compensate the ordinary discharged flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water level control method for a waterway system, such as a tank, a dam, a weir, etc., for controlling the amount of water discharged in a waterway system such as a weir so that the water level reaches a target water level. Effectively utilizes water resources in a waterway system such as tanks, dams, and weirs, regarding a water level control method for a waterway system that controls the amount of water discharged based on each parameter obtained by analyzing a waterway with a 2-tank model. One method is to control the amount of water discharged into the waterway system to keep the water level in the waterway system constant.

FIG. 1 is a block diagram showing an example of the configuration of a water level control device that performs such water discharge amount control. In this figure, 1
is a head tank, and the water supplied through the water conduit 2 is temporarily stored in this head tank 1, and then when the operation valve 3 is opened, the water is discharged through the water discharge conduit 4 to generate water. Rotate machine 5. Also 6 is head tank 1
This deviation detector 6 compares the output (signal S2) of the water level detector 7a with the water level set value signal S1 to obtain the water level deviation e and supplies it to the control device 7. Based on this water level deviation e, the control device 7 controls the operating valve 3 so that the water level in the head tank 1 reaches the target water level.

By the way, in such a water level control device, when calculating the water discharge amount QO from the water level deviation e, an empirically obtained formula such as "rPI control" or "ke" (k, n are constants) is used. Therefore, the inflow 1LQI, which is a disturbance, is not directly taken into account. Therefore, if the inflow QI suddenly changes due to discharge from an upstream dam, a control delay may occur, and the water level in the waterway system may fall outside of the allowable range. There were disadvantages such as an increase in the number of times the operation valve was opened and closed.

In view of the above points, the present invention makes it possible to maintain the water level in the waterway system within an allowable range without increasing the number of times the operation valve is opened and closed, even when the amount of water supplied through the waterway changes suddenly. It provides a water level control method for waterway systems that allows
Analyze the waterway system and calculate the parameters R and A of the Cotank model.
'2 and the sampling period To are obtained in advance, and each of these parameters R-A'2i, the sampling period To, the predetermined modified dead zone δh, and the sampling period To
The water discharge flow rate correction value ΔQO is calculated based on the water level change Δh between then, and the water discharge flow rate QO up to that point is corrected based on this water discharge flow rate correction value ΔQO.

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

First, before explaining the water level control method of a waterway system according to the present invention, a waterway system consisting of a long opening and a head tank is simulated as an unsteady flow equation model, and its outflow flow rate QO1
The water level change when the inflow flow rate QI is changed will be explained.

Figure 2 is a diagram showing the water level response waveform (simulation result) when the outflow flow rate QO is suddenly changed in such a model, and Figure 3 is a diagram showing the water level calculation points shown in Figure 1. . In Figure 1, the solid line L1 shows the water level response waveform at the downstream point N11L1 of the headrace 2a.As shown in the solid line L1, when the outflow flow fLQo changes suddenly, the water level at the Nll point changes at the time of this sudden change. It changes rapidly for a predetermined period of time, and then changes slowly at a predetermined slope. Also, I@2, N on the upstream side of point N111
The water level at point 113 also changes in the same way as the water level at point Nll mentioned above, as shown by solid lines L2 and L3. On the other hand, in such a model, although not shown in the figure, if the inflow flow rate QI is suddenly changed, the water level will remain almost constant until a predetermined period of time has passed from the time when the inflow flow rate QI was suddenly changed, A change in water level occurs after this predetermined period of time has passed.

Next, in the two-tank model, changes in water level when the outflow flow rate QO1 and inflow flow rate QI are changed will be explained. First, the Cotank model will be briefly explained with reference to FIG. As shown in this figure, the water supplied via the waterway a is once stored in the inflow side tank 1a corresponding to the headrace waterway 2, and then passes through the waterway IC provided at the lower part of the inflow side tank 1a. It is supplied to the outflow side tank 1b through the tank 1b. The water stored in this outflow side tank lb is discharged via the discharge channel 4b. Here, if we express the water level of such a tank model using a differential equation, TI A
It becomes t. However, Hl is the water level of the outflow side tank 1b, H2 is the water level of the inflow side tank 1a, A1 is a parameter indicating the floor area of the outflow side tank 1b, A2 is a parameter indicating the floor area of the inflow side tank 1a, and R is a parameter indicating the floor area of the inflow side tank 1a. A parameter indicating the resistance of the waterway IC, TI (TI=A□·R) is a parameter indicating a response delay, and T2 (T2=A2·R) is a parameter indicating a control operation period, which will be described later.

In general, the headrace 2 is long and it can be assumed that A2>A1, so if the inflow flow rate QI and the outflow flow rate QO are changed stepwise in these equations (1) and (2), Hl(t)Hl( ,0)=J(t) is obtained. However, hl indicates the amount of change in the water level of the outflow side tank 1b. If the outflow iQO is changed stepwise in this equation (3), a water level response waveform shown in the m3 diagram can be obtained. As shown in this figure, at time to, the outflow flow fi Q O (see figure (c)) is expressed as ΔQ
If only Q is changed, the water level H1 of the outflow side tank 1b (see figure (A)) will be 1 at time to.If the outflow flow rate QO is kept constant and the inflow flow ft1i:Q is changed stepwise, A water level response waveform shown in FIG. 4 is obtained. As shown in this figure, when the flow of people QI (see figure (b)) is changed to υ at time t1, the water level H1 of the outflow side tank 1b (see figure (a)) changes from time tl to period Tc. After the lapse of time, the slope slowly changes with the slope Δhc.

17 Next, with reference to the above equation (3) and the water level response waveforms shown in FIGS. 3 and 6. Each parameter of the z tank model will be further explained. First, in the above equation (3), the inflow flow rate Q
If I is kept constant and only the outflow flow rate QO is changed, the water level change h s, (t ) at this time can be expressed by the following equation. As is clear from equation (4) and the water level response waveform shown in Figure 3, the parameters R, A2
can be expressed by the following formulas, and since the parameter TI indicates the recovery delay period of the water level when the outflow flow rate QO suddenly changes, TI=Ta...
...(7) can be expressed. Furthermore, in the above equation (1), since 'r1 = Al-L is replaced, the parameter A1 can be expressed by the following equation. Next, in the above equation (3), when the -C1 outflow flow rate QO is kept constant and only the inflow flow rate QI is changed, the water level change b 1 (t) is expressed as 2. From equation (9) and the water level response waveform shown in FIG. 6, the parameter A2 can be expressed as shown in Table 4.

By the way, since the parameter A2 shown in this equation (10) and the parameter A2 shown in the above equation (6) are generally not equal, the parameter A2 shown in the equation (00) of C is replaced with the parameter A'2, and here this ( If we define the equation (10) in 91, we obtain the following equation, and further, if we express the equation (3) in gM with the parameter A'2 shown in the equation (10)', we obtain the following.

Next, the water level response waveforms of the two-tank model shown in FIGS. 3 and 6 will be considered. First, Figure S and Figure 6
As is clear from comparing the water level response waveform shown in the figure with the water level response waveform of the waterway system shown in Figure 1 (see Figure 2), this! The water level response waveform in the tank model is almost the same as the water level response waveform in the waterway system shown in FIG. From this, the response characteristic of the water level H of the waterway system shown in FIG. 1 can be expressed with equal constraints by the response characteristic of the water level H of the outflow side tank 1b in the Ω tank model shown in FIG. 9. Furthermore, if we analyze the water level response waveform in the actual system,
The values of each parameter R, A2-A'2, and A1 of the Ω tank model can be determined from the above equations (5)2 to (10)'.

The water level response characteristics of the waterway system shown in Figure 1 will be discussed below using this one-tank model. First, if we replace the time Tc (see Figure 6) with the time delay constant τ0, we can obtain the above (3).
The water level change h1(t) shown in the equation ' is given by ■. Then, by applying Laplace transform to this equation (6), the following is obtained, and by schematizing this, the block diagram shown in FIG. 7 is obtained. In FIG. 7, 8 is a dead time element that is involved in the delay time (dead time) from when the inflow flow tQI changes until the water level changes, and 9 is a constant element that is involved only in the time constant. After the change ΔQI in the inflow flow rate QI is converted by these dead time element 8 and constant element 9,
At addition point 10, the outflow flow rate change -ΔQO is added and supplied to integral element 11. The integral element 11 is involved in integrating the deviation between the inflow flow rate change ΔQI and the outflow flow rate change ΔQO, and the output of this integral element is supplied to the addition point 12. Further, 13 is a code conversion element, and this code conversion element 13 inverts the outflow flow rate change ΔQO and supplies it to the addition point 10 and the delay element 14. The delay element 14 is involved in the delay time from when the outflow flow rate QO changes until the water level changes, and the output of this delay element 14 is added to the output of the integral element 11 at the addition point 12, and is calculated as the water level. Output.

As described above, since the response characteristic of this waterway system includes the integral element 14, if this were to be controlled continuously, the control algorithm would become complicated. Therefore, in the present invention, a period To is provided as a sampling period of the water level H to eliminate such inconvenience. This sampling period To will be explained in detail below.

Therefore, the sampling period To is set to a length that allows such replacement, for example, several times the time constant TlO.On the other hand, if the sampling period To is made too long, it will be detected. Since the water level exceeds due to the delay, the water level is set to be within the allowable value for the water level rise classification based on the above-mentioned inflow flow rate change ΔQI.

It is set as follows.

An embodiment of the present invention using the above-mentioned parameter R-'r2 and sampling period To will be described below.

FIG. 1 is a block diagram of a waterway system to which the water level control method for a waterway system according to the present invention is applied. In this figure, reference numeral 15 is a transmission element that indicates the transmittance of the waterway section consisting of the headrace 2, head tank 1, and discharge channel 4 shown in FIG. , an integral element 11, and an addition point 10.12. Also, 16
is a control element that controls the outflow flow rate QO of the waterway system, and these control elements include a 16-digit addition point 17, an outflow flow rate control element (digital type regulator) 18, a sampler 2o, and a bold element 19.
Composed of Nyota. Next, these addition points 17 to bold elements 19 will be explained in order.

First, the addition point 17 compares the value indicated by the water level setting command ha with the actual water level to determine the water level deviation, and the outflow flow rate control element 1
Supply to 8. Here, before explaining the function of the outflow flow rate control element 18, the corrected flow rate Δ of this outflow flow rate control element 18 will be explained.
Q OA, ΔQ On and corrected operation period TBD
I will explain about it. First, as shown in the water level response waveform in FIG. 2, both the inflow flow rate QI and the outflow flow rate QO do not change at time t1a, and the integral element 11 at this time
Assuming that the value of x2 (water level change component of M, 2) is δh and the value of water level setting command hO is zero, the output of the control element 16 (outflow flow rate correction value) ΔQO at time tla is ΔQO −−δh−m・・・・・・・・・
...(13), so the constant element 1 at this time
The output (seventh water level component) Xl of 4a and the first water level component x2 are respectively: )(, knee R・δh−m
...(14)x2==δh ...
. . . (] δ5, where m is the gain of the control element 16.

Next, enough time has passed since this time tla, and time t2
a, these first and first water level change components X2,
2 is respectively, )(,=-rt・δ11・+11...
......(16). However, T is time tt
This is the period from a to time t2a. Here, if the allowable range of water level is δ11, then the eighth! water level change component Xi,
The constraint condition for X2 is: X1+X2≧−δh ・・・・・・・・・
...(18), and in this (mate) ceremony, the above (16)
By substituting the equation (17), the following can be obtained. On the other hand, at time t2a, if the terminal condition X2=0 is used to make the water level gauge zero at 7 when the outflow flow t and the change ΔQO are zero, then from the above equation (17), the following is obtained, and this (20 ) and (Y9), the gain m
is, m≦−・・・・・・・・・・・・・・・(21) The positive flow rate ΔQOA (corrected flow 1 within the corrected operation period TBD) becomes 'i expression and (20)
From the formula, the gain m”!, 1 erasure shift is the period T, T≧A2・R・・・・・・・・・・・・・・・(23)
becomes. Therefore, the correction operation period TBD is Tnn=
A2”R・・・・・・・・・(24).Furthermore, in order to make the water level change zero after the correction operation period TBD ends, it is necessary to satisfy the following formula. , if the output of the integral element 11 whose output is a function of time t is differentiated with respect to time t, the following can be obtained.In other words, if the inflow flow rate change ΔQI and the outflow flow rate change ΔQO are made to match, the correction operation period TBD
Changes in water level after completion can be reduced to zero. Here, in order to obtain this inflow flow rate change ΔQI, the above (10)'
If we rearrange the formula, we get Therefore, this period T
If D is made to coincide with the sampling period To, and the water level change during the sampling period To is Δh, then the corrected flow rate ΔQOB after the correction operation period TBD ends is as follows.

Therefore, when the water level at the time of sampling rises by δh from the target water level, the outflow flow rate control element 18 increases the outflow flow QO by . =A24t)
When the amount of time has elapsed, the outflow flow rate QO is corrected by the amount. In addition, the outflow flow rate control element 18 controls the outflow flow rate QO by δh ΔQO=-1 when the water level at the time of sampling falls by δh from the target water level.
・(31) is changed, and then the correction operation period TBD
Only the outflow flow rate QO is corrected when . The outflow flow rate correction value ΔQO obtained by this outflow flow rate control element 18 is held by a hold element 19.

Next, the operation of the embodiment having the above configuration will be explained with reference to the waveform diagram shown in FIG. 1θ and the flowchart shown in FIG. First, when the system is started at time tLD shown in FIG. 1O (step 5PI in FIG. 1), the water level H of the head tank l (see FIG. 1) is detected at this time tID, and Filtering is performed (step 5P2 in FIG. 1), and then initial setting is performed in step SP3, and the process proceeds to step SP4. Since the elapsed time T from time tID is zero here, the process returns to step SP2 via steps SP5 and SF3. After that, steps SP2 and SP4
~SP6 is executed repeatedly. Next, at time t2D shown in FIG. 1θ, since T≧To in step SP4, the correction value ΔQO of the outflow 11QO is determined in the next step SP7, and the water level deviation ΔH from the set water level is determined. Furthermore, in this step SP7, the stored water level H1 is updated, and
The period T is cleared to zero, and the process proceeds to the next step SP8.
It is determined whether the water level deviation ΔH exceeds the water level tolerance range δh. Here, as shown in Fig. 7θ (b), if the water level H exceeds the water level allowable value δh, step SP
Proceeding to 9, it is determined whether the value of the number of sampling times C1 is zero. In this case, since c1=o, step spi.

As a result, the outflow flow control element 18 controls the outflow flow tQ.

As shown in Fig. 1θ), the flow rate ΔQ(J) is increased by the flow rate ΔQO, and the hold element 19
It is held as shown in c). As a result, the water level Ht:t of the head tank 1 decreases as shown in Fig. 1 ←). Then, in the next step 5PII, the value of the sampling number 01 is incremented by -a, and then the process returns to step S2 via step 5P12.5p6=. Thereafter, the value of period T is updated every time steps SP2, SF3, SF3, and SF3 are executed, and each time the value of period T exceeds sampling period To, steps SP4 and S
F3, SF3, SF3.5P13-5P17.5PII
, 5P12, SF3 is executed and the sampling count is 01
The value of is updated. And period TlID from time t2D
has passed and the value of the sampling number C1 is 4. The water level H in the tank 1 is returned to the set water level ho as shown in FIG. Then, in the next step 5PII, the number of sampling c1
is incremented, and after this step 5P12
, SF3 and then returns to step SP2. Next, time t
When a transition period TCD (this transition period TCD is the same length as the sampling period To) has elapsed from aD and the value of the sampling number C1 is incremented to the value 6 in step 5 PII, step 5 P12.5
The sampling count 01 is cleared to zero through P19 and SF3, and then the process returns to step SP2 to return to the initial state.

Also, at the time of sampling, the water level H in the head tank 1
is below the allowable range 1δh on the low water level side,
Steps SP9 to 5P12.5pis, 5P1 mentioned above
Steps 5P20 to 5P25 are executed instead of step 9 to correct the water level.

As explained above, the water level control method for a waterway system according to the present invention analyzes the waterway system and determines each parameter R, A'2 and sampling period T of the J tank model.

are obtained in advance, and each of these parameters R, A; , sampling period To, and predetermined modified dead zone δh,
A water discharge flow rate correction value ΔQO is calculated based on the water level change Δh during the sampling period To, and this water discharge flow rate correction value ΔQO
Since the previous water discharge flow rate QO is corrected based on can be kept within an acceptable range, and the control algorithm at this time is very simple.
The water level can be controlled by a simple circuit configuration.

[Brief explanation of the drawing]

Figure 1 shows an example of a waterway system consisting of a long opening and a head tank. Figure 2 shows the water level response waveform when the waterway system shown in Figure 1 is modeled. Figure 3 shows the water level response waveform shown in Figure 2. Figure 9 is a diagram showing the calculation points of the water level shown! Figures 3 and 6 showing the tank model are shown in Figure 9, respectively! Figure 7 is a diagram showing the water level response waveform of the tank model. Figure 7 is a block diagram showing the transfer characteristics when the waterway system shown in Figure 1 is modeled into three tanks.
Fig. 1 is a block diagram for explaining an embodiment of the water level control method for a waterway system according to the present invention, Fig. 7 is a waveform diagram for explaining Fig. 1, and Fig. 70 is a block diagram for explaining the embodiment. The second waveform diagram, Figure 1, is a flowchart for explaining the same embodiment. 8...Delay element, 9...Constant element, i
i... Integral element, 1.4 a... Constant element, 15... Transfer element, 17... Addition point, 18... Outflow flow rate control element, 19...
...Hold element. Applicant Shinko Electric Co., Ltd.

Claims (1)

[Claims] Water level control in a waterway system that stores water supplied through a waterway and controls the water level by controlling a water discharge operation valve so that the water level becomes a target water level. In the method, analyze the waterway system! Each parameter R-A' of the tank model
2 and sampling period T. are obtained in advance, and each of these parameters R, A'2, sampling period To, and predetermined modified dead zone δb,
A water discharge flow rate correction value ΔQO is calculated based on the water level change Δh during the sampling period To, and this water discharge flow rate correction value ΔQO
A water level control method for a waterway system, comprising correcting the previous water discharge flow rate QO based on.