JPH11202944A - Water conveyance flow rate control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control the flow rate of a conduit and to automatically cope with secular changes. SOLUTION: A control part 20 is stored with a model for water conveyance facilities and when a target outflow from a gate 9 and a valve 5 is set by a setter 21, the control part 20 controls the rotating speed of a pump 6, calculates the loss coefficient of the gate 9 and valve 5 according to the model, and operates the gate and valve so that an opening extent corresponding to the value is reached. The flow rate of the gate 9 and valve 5 is normally monitored and if the flow rate deviates from the target value for longer than a specific time, the model in the control part 20 is corrected to operate the gate 9 and valve 5 again with the corrected model.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the flow rate of water supply, and more particularly to a method for controlling the flow rate of a pump provided at the inlet of a long distance waterway, and the opening and closing of a gate and a flow control valve provided at the outlet. The present invention relates to a method for controlling the flow rate of water conveyance.

[0002]

2. Description of the Related Art Conventionally, a certain river (or pond or the like) is connected to another river (or pond or the like) by a headrace, and a part of water flowing through one river is passed through the other through the headrace. There is a water conveyance system that can supply water to rivers. In such a water introduction facility, the opening and closing of the gate and the valve opening of the flow control valve,
In addition, a control system that automatically controls the number of rotations of the pump is employed to automatically control the amount of water supplied to the river (or lake, pond, etc.) to which water is to be supplied, so that an appropriate amount of water can be supplied.
And as a method of controlling the amount of water supply, the actual amount of water supply is detected at the outlet of the headrace channel to detect the excess or shortage of the water supply flow rate,
When the excess or shortage is detected, the control amount of the gate operation amount of the headrace outlet, the opening operation amount of the flow control valve, and the rotation speed of the headrace inlet pump are determined.

[0003]

In the above prior art,
Since the flow rate at the inlet of the headrace is controlled based on the flow rate detected near the outlet of the headrace, from the change in the inflow flow rate at the inlet until the change appears at the outlet, the flow rate is adjusted according to the length of the headrace. take time. For this reason, when the headrace is long, for example, even if the inflow rate is increased, the increase does not immediately appear at the outlet, and the control system repeats the control to further increase the inflow rate. Then, the flow rate at the outlet eventually exceeds the control target value, and the control in the reverse direction is performed this time, but at this time, the flow rate is over-controlled to a value smaller than the target value. For this reason, in the case of long-distance transportation, the feedback control tends to be unstable, and the flow rate is not constant forever, and there is a problem that it takes time to stabilize the water flow rate. Further, there has been a problem that the aging of the equipment affects the pipe loss of the headrace, the gate opening characteristics, the valve characteristics, the characteristics of the pump on the inflow side, and the control becomes more complicated. Note that if the water conveyance distance is short, there is no need to particularly consider the response time delay to the control command.

[0004] Therefore, the present invention provides a method for controlling the flow rate of a water supply, which enables stable control of the flow rate even in the case of a long water supply channel and automatically responds to changes in the characteristics of various equipment due to aging. It is intended to provide.

[0005]

In order to achieve the above object, the present invention relates to a method for controlling a flow rate of a headrace, which comprises one or more gates provided at the outlet of the headrace. An outlet target value is set for the amount of outflow from each of the valves, so that the total flow rate of the outlet target values set for each of the gates or valves is obtained.
While controlling the intake pump at the inlet of the headrace, the loss coefficient of each of the gates or the valves is calculated using the model of the headrace and the set outflow target value, and the loss coefficient is calculated from the calculated loss coefficient. And the required opening of each of the gates or valves is calculated by using an opening versus loss coefficient characteristic indicating the relationship between the opening of the gate or the valve, and the calculated required opening and the current actual opening are further calculated. And an opening control operation is performed by obtaining an opening operation amount for the gate or the valve from the above.

Further, according to the present invention, the amount of outflow from the gate or the valve is measured at each predetermined control timing, and the measured amount of outflow from at least one of the gates or the valve and the set target value are set. When the deviation from the predetermined allowable value exceeds a predetermined number of times of the control timing, if the state continues continuously, the model of the headrace is modified, and the modified model is A water flow control method is disclosed, wherein the determination of the opening operation amount and the opening control operation based on the determination are performed again.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an outline of a flow control system and a water conveyance facility to which a water conveyance flow control method according to the present invention is applied. In FIG. 1, the water conveyance system is a river 1
And a headrace 3a provided between the lake and the lake 2.
Water from river 1 to lake 2. The headrace 3a is a long-distance transport route that extends for several kilometers, and in the middle thereof, shafts 4a, 4b, and 4c for pressure adjustment are installed at intervals of several kilometers. The shafts 4a, 4b, 4c are erected vertically with respect to the headrace 3a.
b, 4c contain water at a predetermined water level.
The water is prevented from flowing into or out of the shaft according to the fluctuation of the water pressure in the area a.

A pump 6 is installed near the water intake of the headrace 3a, and pumps up water from the river 1 to flow into the headrace 3a. In the vicinity of the pump 6, a flow meter 7 for detecting the inflow flow rate QB from the water conduit 3a is installed. Headrace 3a
, The headrace channel 3b branches off while being connected to the shaft 4c, and guides water to the lake 2. An openable / closable flow control valve 5 is provided in the middle of the water conduit 3b to supply and stop the water to the lake 2. Near the entrance of the flow control valve 5, an outflow flow QV flowing out of the water conduit 3b is provided. A flow meter 8 for detecting the pressure is provided. Further, a gate 9 and a flow meter 13 for detecting an outflow flow rate QG therefrom are installed in the headrace 3a behind the shaft 4c, and the opening of the gate 9 is detected by the opening meter 10. You. The opening of the flow control valve 5 is detected by an opening meter 11, and a gate driving device 12 is provided to drive the gate 9.

The control device 20 includes the above-described flow meters 7, 8, 1
3. Capture the detection results of the opening meters 10 and 11 and set
The target values QV = Qv0 and QG = QG0 of the flow rate set in 1
Is realized by controlling the rotation speed of the pump 6 and the openings of the gate 9 and the valve 5 and is constituted by an arithmetic unit and an electronic computer having a memory.

Next, a control method in the control device 20 will be described. This control method is shown in the flow chart of FIG. 2, which is an example of the water flow control method of the present invention. In FIG. 2, first, a model of the water conveyance equipment is initialized by the setting device 21 (step 201). This model uses parameters such as the structural dimensions of the water conveyance equipment, the loss coefficient for water flow, the characteristics of the flow control valve 5 and the gate 9, and the like.
When a mathematical model representing the relationship between the water level, flow velocity, flow rate, etc. of each part, and the size of each part of the water conduit, the loss coefficient, and the outflow target values of the gate and the flow control valve are given, the loss coefficients fG, fV of the gate and the flow control valve are given. Can be calculated. Details of this model will be described later.

Next, target values QG0 and QV0 of the outflow amounts QG and QV are initially set by the setter 21 (step 202).
In the steady state, between the inflow QB and the outflow QG, QV

(Equation 1) Holds, the target values QG0, QV0
Is given, the desired value of the inflow QB0 is given by their sum:

(Equation 2) When the target value is set (including resetting) by the setting device 21, a signal for notifying that the setting has been changed is sent from the setting device 21 to the control device 20, and the change flag in the control device 20 is set. It shall be turned on.

When the initialization is completed in steps 201 and 202, control parameters j and jm are set to 0 and j1 (positive integers), respectively (step 20).
3) Check the above-mentioned change flag (step 20)
4). Immediately after the target value of the outflow is initially set, the change flag is on, so the process proceeds to step 205, where the change flag is turned off, and the set target values QG0, QV0 of the outflow are set. A model calculation is performed using the target value QB0 of the inflow amount, which is the sum of the above, and the loss coefficients fG and fV of the gate 9 and the flow control valve 5 at the target value are calculated (step 205). Next, the openings of the gate 9 and the flow control valve 5 are taken from the opening meters 10 and 11 (step 20).
6), the operation amounts of the gate 9 and the valve 5 are calculated (step 2)
07). For the calculation of the manipulated variable, the “opening-loss coefficient” curves of the gate 9 and the flow control valve 5 are stored in the control device 20 in advance, and by referring to this, the loss coefficient calculated in step 205 is calculated. A corresponding opening degree is calculated, and further, how much the opening degree of the gate 9 and the valve 5 should be operated is calculated from the calculated opening degree and the current opening degree taken in step 206.

When the opening amounts of the gate and the valve are determined, the gate 9 and the flow control valve 5 are operated in accordance with the determined operation amounts. The rotation number of the pump 6 is controlled so as to give the inflow amount (step 208). Then, the control parameters j and jm are set to 0 and j2, respectively (step 20).
9) The control is shifted to the control in the steady state.

In the control in the steady state, the amount of outflow is monitored periodically, and the model is corrected when the amount of the outflow exceeds an allowable deviation from the target value. That is, first, it is checked whether or not the control timing has come (step 210). This timing is determined in advance,
Let T be the period. At the control timing, the flow rates QB, QG, QV detected by the flow meters 7, 8, 13 are taken in (step 211), and the outflow quantities QG, QV and their target values QG.
It is checked whether the deviations from 0 and QV0 are both equal to or smaller than a predetermined allowable deviation (step 212). Here, if it exceeds the allowable deviation, the parameter j is incremented by 1 (step 213), and it is checked whether j ≧ jm (step 214). If this condition is not satisfied, the process returns to step 204, but since the change flag is turned off, the process proceeds to step 210, and it is checked whether the detected flow rate is equal to or less than the allowable deviation at each control timing. If the condition of not more than the allowable deviation is not satisfied, the condition of j ≧ jm is satisfied while the above operation is repeated (Yes in step 214). The operation of the gate 9, the flow control valve 5, and the pump 6 is performed again by the processing of step 205 and subsequent steps. Step 21
If both of the outflow amounts QG and QV are equal to or less than the allowable deviation before the condition 4 is satisfied (Yes in step 212),
The parameter j is reset to 0 again (step 20)
3). During the above-mentioned repetitive control, the setting unit 21
When the target value is changed, the change flag is turned on. In this case, as in the case of the initial setting, step 2 is performed.
05 or less model calculation, gate 9, valve 5, and pump 6
Is performed.

According to the above-described processing, at least one of the outflow amounts QG and QV has an error greater than or equal to the allowable deviation with respect to the set value, for the time j1 · T or more given by the product of the control cycle T and the parameter j1. If you continue to do so, the model will be modified as if it were aging. Also,
After operating the gate 9, the valve 5, and the pump 6, the above cycle T
If the state where at least one of the outflow amounts QG and QV continues to have an error that is equal to or more than the allowable deviation with respect to the set value continues for a time j2 · T or more given by the product of Will be done. Therefore, when the target value is changed or when the model is modified based on aging, an operation of a gate or the like is performed, and it is observed during the time j2 · T whether the flow rate change due to the operation is sufficiently settled at the outlet. As described above, if the parameters j1, j2, and T are appropriately determined according to the length of the headrace, stable control can be performed both when the target value is changed and when the model is corrected.

After the operation amount is determined, for example, when the operation is performed so as to increase the flow rate flowing through the flow rate control valve 5, the flow rate control valve 5 is first opened, the gate operation of the gate 9 is performed, and then the flow rate control is performed. Valve 5 is closed. That is,
The flow control valve 5 and the gate 9 are not operated at the same time, and the opening operation is prioritized. This prevents the water level of the shaft 4 from overflowing. Further, in order to prevent hunting, the operation is performed gradually, and after one operation is completed, the other operation is performed.

Next, a method of correcting the model in step 215 will be described. This is because if the loss factors calculated before correction are fG and fV,

(Equation 3) Using the counts fG 'and fV' obtained in the above as loss coefficients, the manipulated variable in step 206 is determined. Here, the values of CG and CV are assumed to be constant in magnitude, and the sign thereof is negative if the measured outflow is larger than the target value and exceeds the allowable deviation, and is positive if it is small and exceeds the allowable deviation. And 0 if within the allowable deviation.

Next, the details of the model used in step 205 will be described. FIG. 3 shows the water guide facility shown in FIG. 1 in more detail, and the same reference numerals are given to the same facilities as those in FIG. 1 is a schematic plan view from the top (a vertical shaft portion is a vertical sectional view), but FIG. 3 shows the vertical direction along the water conduits 3a and 3b and the vertical shafts 4a to 4d. FIG. The headrace from the gate 9 to the lake 2 is simplified in FIG. 1, but there is also a shaft 4d, through which water is transferred from the underground waterway 3a to the lake 2 via the shaft 4d. And In FIG. 3, positions A to K are as shown in Table 1.

[Table 1] The water level at each position α is Hα, and the inner diameter of the pipe is D
α, the flow rate is Vα, the flow rate is Qα, and the flow rate from the position α to the position β is Vαβ, and the distance between the positions α and β is Lαβ (α and β are applicable from A to K in Table 1). The following (Equation 4) to (Equation 16) hold.

(Equation 4)

(Equation 5)

(Equation 6)

(Equation 7)

(Equation 8)

(Equation 9)

(Equation 10)

[Equation 11]

(Equation 12)

(Equation 13)

[Equation 14]

(Equation 15)

(Equation 16) Here, the constant n is given by Manning's equation, g is the gravitational acceleration, fαβ is the loss head coefficient between the positions α and β, and these are constants given in advance. FG and fV are loss coefficients of the gate 9 and the flow control valve 5. (Equation 4),
(Equation 7), (Equation 8), (Equation 11) and (Equation 13) represent equations for the head loss due to friction between the positions α and β, and (Equation 5), (Equation 6), (Equation 9), And (Equation 10) represents the equation of the head loss due to the diversion, and (Equation 12) represents the head from the shaft 4c to the lake 2
Represents the head loss due to the flow control valve 5 up to
4) represents the equation of the head loss due to the head from the shaft 4d to the lake 2, and (Equation 15) and (Equation 16) represent the equation of the flow distribution accompanying the diversion.

(Equation 4) to (Equation 16)

[Equation 17] When the loss coefficients fG and fV are obtained using the relationship
8) (Equation 19) is obtained.

(Equation 18)

[Equation 19] Therefore, the inflow flow rate QB and the outflow flow rate QV from the flow control valve 5
Using the target values QB0 and QV0 of (Equation 18), the loss coefficient f
V can be calculated. However, DIK of (Equation 18),
QIK is the diameter and flow rate of the pipe at the position where the pipe branches from the shaft 4c to the headrace 3b, and QIK = QV. (Equation 19)
Therefore, paying attention to the fact that QC = 0 and QD = QB in the steady state, the target values QB of the inflow flow rate QB, the outflow flow rates QV and QG are obtained.
The loss coefficient fG can be calculated using 0, QV0, and QG0. The above is the mathematical expression model used in step 205 of FIG.

In the embodiment described above, water is introduced from a river to a pond. However, it goes without saying that a river may be a river, a pond may be a river, a pond may be a pond, or the like. . In addition, the example of the water conduit having two branches of 3a and 3b is shown, but the present invention is not limited to the two branches.
One outlet or two or more branches may be used, and the present invention is applicable even if the number of shafts changes according to the length of the headrace.

[0021]

As described above, according to the water flow control method of the present invention, it is possible to control the flow rate stably, and it is also possible to automatically cope with the aging of the equipment characteristics.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a flow control system and a water conveyance facility to which a water conveyance flow control method according to the present invention is applied.

FIG. 2 is a flowchart illustrating a method for controlling a water flow rate according to the present invention.

FIG. 3 is an explanatory diagram of a water conveyance facility model.

[Explanation of symbols]

 Reference Signs List 1 river 2 lake 3a, 3b headrace 4a, 4b, 4c shaft 5 flow control valve 6 pump 7, 8, 13 flow meter 9 gate 10, 11 opening meter 12 gate drive device 20 control device 21 setting device

Claims (2)

[Claims] 1. A headwater flow control method for controlling a flow rate of a headrace, comprising: setting a discharge target value for an outflow amount from each of one or a plurality of gates or valves provided at a headrace outlet; Or controlling the intake pump at the inlet of the headrace so as to obtain the total flow rate of the set target value for each of the valves, and using the model of the headrace and the set runoff target value. Calculate the loss coefficient of each of the gates or valves, and calculate the loss coefficient of each of the gates or valves from the calculated loss coefficient using an opening degree-loss coefficient characteristic indicating a relationship between the loss coefficient and the opening degree of the gate or valve. The required opening degree of the gate or the valve is calculated from the calculated required opening degree and the current actual opening degree to perform the opening degree control operation. Water flow control method. 2. An outflow amount from the gate or the valve is measured at each predetermined control timing, and a deviation between the measured outflow amount and the set set target value for at least one of the gates or the valves is determined. When the state exceeding the predetermined allowable value continues continuously beyond the predetermined number of times of the control timing, the model of the headrace is corrected, and the corrected model is used again. 2. The method according to claim 1, wherein the determination of the opening operation amount and the opening control operation based thereon are performed.
2. The method for controlling the flow rate of water conveyance according to item 1.