JPS6216283B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gate (hereinafter referred to as
This relates to a control device for a group of irrigation canal gates. Fig. 1 is a plan view of the irrigation canal, Fig. 1A is a sectional view taken along line A-A in Fig. 1, and Fig. 1B is a sectional view taken along line B-B in Fig. 1. . In these diagrams, 1 is a river (or other irrigation canal), 2 is an irrigation canal, and 3 is an irrigation canal.
is a water intake gate, 4 and 5 are respective irrigation canal gates (hereinafter also simply referred to as gates), and R refers to the section between one gate and the adjacent gate in the irrigation canal 2, which is called a reach. The irrigation canal 2, which carries water from the river 1 through the water intake gate 3, ultimately connects to other rivers, etc., but it is divided into multiple reaches R by gates 4, 5, etc., and each reach R From there, water is supplied to the demand side as, for example, agricultural water by means (for example, a water pump) not shown. The irrigation channel 2 is inclined at a constant slope so that water can flow smoothly. Each of the gates 4, 5, etc. is, for example, an overflow gate with an overturning type, and the flow rate that overflows the gate changes depending on the angle of overturning, and the role of these gates is to control the water level in each reach R. It is in. Despite large fluctuations in water demand, by properly controlling the overflow flow rate of each gate, it is possible to prevent invalid discharge (flow rate that is ultimately discharged from irrigation canal 2 to other rivers, etc.) and overflow from the canal. It is desirable to control the water level in each reach so that it does not become extremely low, and the present invention relates to a control device for an irrigation canal gate in this sense. FIG. 2 is a conceptual diagram showing a conventional irrigation canal gate control device. In the figure, 6 is a water level gauge, 7 is a water level regulator, and 8 is a gate operating device. The control device shown in FIG. 2 detects the water level directly downstream of the gate 4 with a water level gauge 6, and based on the deviation from the set water level _h0 , issues a command to the gate operating device 8 with the water level controller 7 to turn the gate 4 on. The water level directly downstream is controlled by moving the water level to match the set water level, and this kind of control is performed at each gate installed in the irrigation canal. The water intake gate 3 is also controlled in the same manner, and the opening degree of the gate at the end of the irrigation channel is generally fixed, and the amount of water flowing beyond this gate becomes an invalid discharge. Such conventional control devices have the following two problems. One is that when a disturbance (flow rate fluctuation) occurs somewhere in the irrigation canal, each controller 7 detects the disturbance as a change in the water level h immediately downstream, and the operating device 8
Therefore, the delay time until the gate 4 is operated is large. Hereinafter, a detailed explanation will be given with reference to FIG. 1 again. As previously explained, the section from one gate 4 to the downstream gate 5 is called the reach R, and fluctuations in the amount of water taken in by consumers during this reach R, or changes in the downstream gate 5 The operation causes fluctuations in the water level within the reach R. First, the water level fluctuation due to the operation of the downstream gate 5 is as follows.
It appears at the water level immediately upstream of the downstream gate 5 (referred to as the downstream water level of the reach R). In addition, the influence of fluctuations in the amount of water taken in from irrigation canal 2 is that when the irrigation canal is an open channel, the propagation speed of the flow rate fluctuation phenomenon in the open channel is more downstream than when it is directed upstream from the point of occurrence of fluctuation. Reach R is generally faster than the water level directly downstream of Gate 5.
appears earlier at the downstream water level (the water level immediately upstream of gate 5). Furthermore, fluctuations appear in the water level immediately downstream of gate 4, and even if gate 4 is operated, there is a time delay before the amount of water from the upstream side changes due to the fluctuation, so during this period, the water level fluctuates greatly. There could also be cases where consumers were unable to take in the required amount of water due to flooding or the water level dropping too low. The second problem concerns the set water level. Generally, the height H to the top of the irrigation canal and the height Hg of the gate (see Figure 1B) are planned based on the uniform water depth at the maximum planned water flow. Therefore,
If this height is used as the set value for the downstream water level, there is a possibility that water will overflow or be discharged ineffectively on the downstream side when the water is still (zero flow rate). This will be explained below with reference to FIG.
In Fig. 3, 9 is the top of the waterway. Generally, irrigation canals are constructed to allow water to flow at a constant slope, so the top of the canal is also sloped in the same way. When the maximum planned water flow flows through this channel,
The water flow has the same slope, and the water surface slopes like S ₂ . When there is still water with zero flow rate, the water surface becomes horizontal like S ₃ . Therefore, if the water level immediately downstream of gate 4 is set to the gate height Hg, when the planned water flow is flowing, the water surface S ₂ has a slope along the channel crown 9, so it will not overflow. When the flow is still water and the flow rate is zero, the water surface becomes horizontal as shown in _S1 , so water overflows from the top 9 of the waterway. Furthermore, if the water level immediately downstream of the gate 4 is set to the height Hg of the gate as described above, water will flow beyond the gate 5 during still water, leading to invalid discharge. Therefore, if the water level directly downstream of the gate 4 is set low to prevent such overflow or invalid discharge during still water, there may be cases where the amount of water required by the demand side cannot be supplied satisfactorily. The water level control device immediately downstream of the gate as shown in FIG. 2 has the above-mentioned problems. Therefore, a device that controls the water level directly downstream of the gate to a constant level may be considered. With such a device, the problems described with reference to FIG. 3 do not occur. However, when considering the water intake gate 3, the water level immediately upstream thereof is nothing but the water level of the river, and the river water level itself does not change when the water intake gate 3 is opened or closed. Such control is therefore meaningless, and it is difficult to prevent ineffective discharge at the end gate. The present invention has been made in order to solve the problems of the prior art as described above, and therefore, an object of the present invention is to enable irrigation canals to follow sudden changes in water demand well, and to To provide an irrigation canal gate control device that performs control to eliminate overflow and invalid discharge from a canal until the maximum planned water flow. In order to achieve the above object, in the present invention,
The above-mentioned facility is constructed in such a way that an irrigation canal in which water is introduced from a water source through an intake gate is divided into multiple sections by gates (hereinafter referred to as irrigation canal gates) along the water flow direction, and water is supplied from each section to the demand side. The first step is to calculate the total amount of water demand in each division downstream from the i division in any division (the i-th division counting from the water source side, where i is any positive integer) among the multiple divisions. means, a second means for performing advance calculation or delay calculation on the obtained total demand water amount and outputting the result, and comparing the downstream water level in the i section with the set water level, and adjusting the water level so that the deviation becomes zero. third means for generating an regulated output on said i;
A fourth means for determining the amount of water flowing from the upstream side to the downstream side beyond the irrigation canal gate on the immediately upstream side of the division (hereinafter referred to as irrigation canal gate i), and the output from the second means and the third means and a fifth means for controlling the opening degree of the irrigation canal gate i so that the sum of the adjustment output and the adjustment output is the set flow rate, the water amount determined by the fourth means is the actual value, and the deviation between the two is zero. It is characterized by having Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 4 is a configuration diagram showing an embodiment of the present invention.
The embodiment shown in the figure shows the configuration of the control device at the i-th reach R _i from the upstream in the irrigation canal. It is assumed that there are N such reaches in series in the irrigation canal. Sum of water demands on the downstream side of reach R _i , including the i-th reach R _i

Find [Formula] by calculation. Here, Q _k represents the amount of water being taken in at the k-th reach at that moment, and if a measured value can be obtained, the measured value is used, and if it cannot be obtained, the estimated value is used. The arithmetic unit 12 is a delay or advance arithmetic unit, and
Input water demand sum value

For [Formula], by applying delay operation or advance operation,
The value of the demand sum before L _i time or the value of the demand sum after L _i time is output. 13 is a water level regulator, which measures the reach downstream water level H ₁ , _i+1 measured by the water level gauge 14 and the reach downstream water level setting value H
The deviation between ₀ and _i+1 is input, and proportional-integral-derivative (PID) control is performed so that it becomes zero. The target flow rate Q of the flow rate overflowing the gate 11 is calculated by adding the output of the arithmetic unit 12 and the output of the water level regulator 13.
₀ , _i . A gate such that the flow rate overflowing the gate 11 becomes the target flow rate Q 0, _i from the water level H ₁ , i just upstream of the gate 11 and the water level H ₂ , _i just downstream of the gate 11 measured by the water level gauges ₁₅ and ₁₆ , respectively. The opening degree is calculated as shown below by the opening degree controller 17, and the gate 1 is controlled via the gate operating device 18 based on the calculation result.
1, the above gate opening degree is achieved. In the case of an overturning gate, the overflow flow rate Q is determined by the following empirical formula (1) when the water level immediately upstream of the gate is H ₁ , the water level immediately downstream is H ₂ , and the gate height is D, as shown in Figure 5. or (4) is known to be given. However, it is assumed that h ₁ =H ₁ -D and h ₂ =H ₂ -D. (i) When h ₂ 0, Q is given by the following equation (1). Q=C・B・h ₁ ¹ . ⁵ ………(1) However, Q: flow rate, B: gate width (see Figure 1B), and C: flow coefficient. C is 0<h1/
When D<6, it is given by the following equation (2) (Ishihara-Ida equation). C=1.785+(0.00295/h ₁ +0.237・h ₁ /D) (1+ε) ......(2) ε is when D is 1m or less, ε=0, D is 1m
In the above case, ε=0.55(D-1). When 0<D/h ₁ <0.06, the following equation (3) (Rouse
C is given by the following formula. C=3.131(1+D/h ₁ ) ^1.5 ( ³ ) (ii) When h ₂ >0, Q is given by the following equation (4) (Villemonte's equation). Q=Q ₁ {1-(h ₂ /h ₁ ) ⁿ } ^{0. 385} ………(4) However, Q ₁ is the flow rate calculated in (i) above, n is a coefficient depending on the shape of the gate, and is generally 1.5 for a full-width weir type gate. In the case of (i) above, neither equations (2) nor (3) above can be applied in the range of 6h ₁ /D1/0.06, so
Equation (2) is used for h ₁ /D8, and equation (3) is used for h ₁ /D>8, and when C>3.5, C=3.5. Although the relationship between the gate opening degree and the gate height differs depending on the gate, it is uniquely determined and known. Therefore, the flow rate Q is calculated from H ₁ , H ₂ and the gate opening according to equations (1) and (4) above. Deviation ΔQ between this flow rate Q and target flow rate Q _0,i (=Q _0,i −
Q) is determined, and if the absolute value of ΔQ is smaller than the set dead zone Qε, the opening degree of the gate 11 is left at the current opening degree. If it is larger than the dead zone, ΔQ
If is positive, D is made small, and if ΔQ is negative,
Calculate the flow rate when the gate opening degree is changed by Δτ in the direction of increasing D, and the absolute value of ΔQ is the dead zone Qε
By repeating this process until the opening becomes smaller, a predetermined opening is obtained. The delay/advance time of the target flow rate applied in the calculator 12 is determined as follows. First, when delaying, the delay time is set to zero for the first reach gate, that is, the water intake gate. Let T _i be the propagation time from upstream to downstream in the i-th reach. T _i varies depending on the flow rate and water level, but
This is for the maximum planned water flow. This can be determined by measurement or, if determined theoretically, as follows. The propagation speed of the waterway is (√・+
v), T _i = R _i /(√・_i
+v _i ). However, R _i is the reach distance, g
is the gravitational acceleration, h _i is the water depth, and v _i is the average flow velocity. h _i and v _i are those at the time of uniform water depth of the maximum planned water flow. The delay time L _i is the propagation delay time from the water intake gate, i.e.

Let it be [formula]. Based on the predicted or planned intake flow rate,
When the target flow rate is given earlier, the advance time is first set to zero using the most downstream N reach gate as a reference. Head upstream and advance by a certain amount of time. In other words, the advance time L _i of the i-th reach is

Let it be [formula]. FIG. 6 is a block diagram showing another embodiment of the present invention. The difference between the embodiment shown in the same figure and the first embodiment shown in FIG. 16 is removed), the flow rate of the waterway measured by the flow meter 20 is fed back, and the opening degree of the gate 11 is adjusted by the flow rate regulator 19 via the gate operating device 18 so that it matches the target flow value.
The point is that it uses PID control. As a result, more precise controllability can now be obtained. Next, assuming an irrigation canal gate as shown in FIG. 7 consisting of gates G ₁ to _{G 3} , a characteristic diagram showing the effects of the present invention in comparison with that of a conventional device is shown below. Shown in Figure 7A. In FIG. 7A, A shows the case according to the present invention, and B shows the case according to the conventional device. Please refer to FIG. 7 and FIG. 7A. As shown in the figure, it is assumed that the water demand _Q2 changes in a stepwise manner. In the control device according to the present invention, as shown in FIG. 7A, immediately after detecting this, the flow rate Q _g1 of the most upstream water intake gate G ₁ increases. On the other hand, the second gate _G2 detects a change in the water level _{of H1, 3 after} time _{T2 '} after the change in the demand water amount Q2, and the flow rate _Qg2 starts to increase. Furthermore, _one hour after the change in the water demand _Q2 , a flow rate increase command is issued and the flow rate _Qg2 rises. In contrast, with conventional downstream water level control devices,
As seen in Fig. 7A (b), the water level H _{2 , 2 immediately downstream of the second gate G 2 is detected} after T ₂ ″ time after the change in the water demand Q ₂ , and the flow rate Q _{g 2} begins to increase. However, Since _the flow rate upstream of this gate _G2 is not increasing, even if gate _G2 is knocked down, the flow rate will no longer increase beyond a certain point.Up to the water level _H2,1 immediately downstream of the most upstream water intake gate _G1 . The change occurs after (T ₂ ″+T ₁ ) time after the change in the demand water amount Q ₂ , and from this point on, the flow rate Q _g1 of the water intake gate G ₁ starts to increase. Furthermore, it takes T ₁ hour for this effect to reach the second gate G ₂ , and it takes (T ₂ ″ + 2T ₁ ) hours for the net flow increase. However,
For simplicity, the propagation time to the upstream side and the propagation time to the downstream side are assumed to be equal. In this way, the longer the change in the gate flow rate, which is the operation water amount, is delayed with respect to the fluctuation in the demand water amount, which is the disturbance, the greater the change in the water level during this period. According to this invention, since the water level to be controlled is the reach downstream water level, there is no inconvenience in setting the water level as described above with respect to the prior art. Also, if the gate moves due to fluctuations on the downstream side, it will immediately
This is a change in the upstream water level, which is transmitted to the upstream side without delay, such as when the upstream gate is operated. Furthermore, the flow rate is set according to the water demand on the downstream side, and the gates are operated in sequence, taking into account the delay in the arrival of the flow rate from the upstream side using a calculator, resulting in a stable reach downstream water level with little fluctuation. control.

[Brief explanation of the drawing]

Figure 1 is a plan view of the irrigation canal, Figure 1A is a sectional view taken along line A-A in Figure 1, and Figure 1B is a cross-sectional view of the irrigation canal.
Figure 2 is a conceptual diagram showing a conventional irrigation canal gate control device, Figure 3 is an explanatory diagram showing the relationship between the set water level and overflow in an irrigation canal, and Figure 4 is a cross-sectional view taken along line B-B. FIG. 5 is an explanatory diagram of specifications necessary for calculating the overflow flow rate in an overturning gate; FIG. 6 is a configuration diagram showing another embodiment of the present invention; FIG. The figure is a schematic diagram of a certain irrigation canal gate, and FIG. 7A is a characteristic diagram showing the effects of the present invention when the irrigation canal gate shown in FIG. 7 is used in comparison with that of a conventional device. Description of symbols 1...River, 2...Irrigation canal, 3...Water intake gate, 4, 5...Irrigation channel gate, 6...Water level gauge, 7...
Water level regulator, 8...gate operating device, 9...channel top,
11...Gate, 12...Arithmetic unit, 13...Water level regulator, 14-16...Water level gauge, 17...Opening degree regulator, 1
8... Gate operating device, 19... Flow rate regulator, 20... Flow meter.

Claims (1)

[Scope of Claims] 1. An irrigation canal in which water is introduced from a water source through a water intake gate is divided into multiple sections by gates (hereinafter referred to as irrigation canal gates) along the water flow direction, and water is supplied from each division to the demand side. Any division (the i-th division counting from the water source side, where i is any positive integer) among the multiple divisions of the facility
, a first means for calculating the total amount of water demand in each section downstream from the i section; a second means for performing a forward operation or a delay operation on the determined total amount of water demand and outputting the result; a third means for comparing the water level on the downstream side with the set water level and generating an adjustment output so that the deviation becomes zero; and an irrigation canal gate immediately upstream of the section i (hereinafter referred to as irrigation canal gate i). a fourth means for determining the amount of water flowing from the upstream side to the downstream side beyond the limit; and a fifth means for controlling the opening degree of the irrigation canal gate i so that the determined water amount is an actual value and the deviation between the two becomes zero. 2. In the control device for an irrigation canal gate as set forth in claim 1, when the second means performs a delay calculation, the delay time applied by the calculation is calculated from the most upstream segment including the water intake gate. A control device for an irrigation canal gate, characterized in that a delay time for arrival of a flow rate to reach the i section is selected. 3. In the control device for an irrigation canal gate as set forth in claim 1, when the second means performs an advance calculation, the advance time calculated by the calculation is calculated from the most downstream section of the irrigation canal. A control device for an irrigation canal gate, characterized in that the time required for the flow rate to propagate the distance to the i section is selected. 4. In the irrigation canal gate control device according to any one of claims 1 to 3, the fourth means controls the water level immediately upstream and downstream of the irrigation canal gate i. A control device for an irrigation canal gate, comprising means for determining the amount of water flowing from the upstream side to the downstream side beyond the gate i.