JP2765021B2 - Water distribution control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention combines natural drainage from a reservoir and pumping water from a water purification plant to distribute tap water and maintain appropriate junction pressure. The present invention relates to a water distribution control method for water distribution.

B. Summary of the Invention The present invention relates to a water distribution control system that supplies natural water by merging natural flowing water and pump pressure water, and when the supplied water distribution amount is equal to or greater than the basic water distribution amount, the basic water distribution amount is based on the natural flowing water. The constant flow rate control of the electric control valve based on the flow rate set value is ensured, and fluctuations exceeding the basic water distribution amount are secured by controlling the number of water distribution pumps and constant control of the estimated end pressure by variable speed control. If the flow rate is less than the water flow rate, the flow is controlled only by natural drainage water.The flow rate is controlled by the flow rate set value corrected according to the rise of the junction pressure. This is a water distribution control method that can respond quickly to fluctuations in water distribution and can be fine-tuned.

C. Prior Art As a general water distribution method, there are a method using natural drainage water from a distribution reservoir and a method using pump water supply from a water purification plant.

From the point that electricity rates are low, we want to use natural sewage from distribution reservoirs as a base, but we cannot respond to sudden changes in the amount of water used because the flow rate is adjusted by opening and closing electric valves.

On the other hand, the pump pressure water supply requires an electric charge and a high water unit price. However, if the variable speed control is used for the pump control, the responsiveness to a change in the amount of water used is better than that of the flow rate control by opening and closing the electric valve.

Depending, as a water supply distribution system, as shown in FIG. 4, and the natural flow sewage from distributing reservoir W _A being water via the electric control valve V _A, purification plants W distribution from _B pump P _11, ... , P _1n
The valve V _11, by ..., and pumping water to be water via the V _1n, example of water distribution by merge at a predetermined point N to the city pipe network NET is employed relatively large in local cities.

D. Problems to be Solved by the Invention In such a water distribution system, if the total amount of natural sewage and the total amount of water for pumping are set in advance and the method of distributing water is taken in advance, each time of the day Since the amount of water used in the zone is not always constant, it is difficult to always maintain an optimum pressure and distribute an appropriate amount of water in accordance with a load change.

In addition, the natural flow sewage from distributing reservoir W _A constant flow rate ensure,
If you take the method of supplementing the rest with pumping from the water purification plant W _B ,
Fluctuations in the amount of water used, for example, when the amount of water used falls below the fixed flow rate (basic water distribution amount), the secondary pressure (N-point pressure P _N ) of the electric control valve _VA rises more than necessary.

The present invention has been made in view of the above disadvantages,
If the supply water supply is less than the basic water supply, the flow rate of the natural drainage water shall be controlled, and the fluctuation more than the basic water supply shall be based on the constant control of the estimated end pressure by pump pressure water supply. It is an object of the present invention to provide a water distribution control method for distributing water while always maintaining an appropriate junction pressure according to the conditions.

E. Means for Solving the Problems In a water distribution control system that combines and supplies pump pressure water based on the amount of natural sewage, a flow meter that detects the flow rate in the natural sewage channel and an electric control valve that controls the flow rate are provided. On the other hand, a variable speed control that pumps flowing water into the flow path from the water purification plant, a plurality of water distribution pumps that are controlled in number, and a flow meter that detects the pump discharge flow rate are provided. A flow rate setting correction unit that outputs a preset flow rate set value when the flow rate is lower than the pressure, and a reduced flow rate corresponding to the fluctuating pressure as a set value when the junction pressure is higher than an appropriate pressure; A flow control unit that drives the electric control valve that controls the flow rate of the natural sewage by an operation command based on a deviation between the set output of the correction unit and the flow rate of the natural sewage; and a junction pressure lower than the appropriate pressure. In this case, the pressure at which the junction pressure and the pump discharge flow rate are input, the number of water distribution pumps is controlled, and the water distribution pump is controlled at a variable speed based on the deviation between the set pressure and the junction pressure based on the pump discharge flow rate to perform constant control of the estimated end pressure. A water distribution system is configured by the water distribution control device including the control unit.

F. Action When the supply water supply is equal to or greater than the basic water supply, the natural water supply is secured for the basic water supply by constant flow control using an electric control valve based on the set flow, and for the variable water supply that exceeds the basic water supply, The pump pressure water supply is ensured by controlling the number of pumps based on the pump discharge flow rate, and by controlling the estimated terminal pressure to be constant with the variable speed control of the water distribution pump based on the deviation between the set pressure and the junction pressure based on the pump discharge flow rate. In the case of less than the water distribution amount, the water distribution pump is stopped, the flow rate of the natural drainage water for the electric control valve is controlled based on the set flow rate corrected in accordance with the pressure fluctuation exceeding the appropriate pressure at the junction, and the junction pressure is adjusted to the distribution flow rate. Water distribution is maintained properly according to the requirements.

G. Embodiment Next, an embodiment of the present invention will be described based on the block diagram of the water distribution control system in FIG. The same symbols in FIG. 4 as those in FIG. 4 indicate the same functions or corresponding parts as in FIG. In Figure 1, Q _A, Q _B is the flow meter, Q _A detects the flow rate of the natural flow sewage Q _B is for detecting the discharge flow rate of the water distribution pumps. The E _Q is the flow rate converter, E _P is a pressure transducer. The water distribution control device DC includes a flow rate setting correction unit AQS, a flow rate control unit LC, and a pressure control unit PC.

Flow rate setting correction unit AQS is configured to perform the correction in accordance with the value of the merging point pressure P _N of the set flow rate Q _S in the natural flow sewage. That is,
As shown in the characteristic graph in the flow rate setting correction unit AQS, the junction pressure at which correction is started is P ₁ , the maximum value of the junction pressure is P ₂ , and the junction pressure _PN is equal to or less than the correction start pressure P ₁ in the case of setting the flow rate Q _S is kept constant, the confluence point pressure P _N is set at the confluence point pressure P ₁ when it becomes the proper pressure P ₁ or more flow Q _S value confluence pressure maximum value P ₂ depending on the drop characteristics to reduce the set flow rate Q _S in accordance with the correction line connecting the set flow rate zero point is intended to correct.

The flow control unit LC, C ₁ is a comparator, and calculates the difference ΔQ between the flow rate to Q ₁ natural flow sewage and the set flow rate Q _S. C ₂ is the controllers, input the deviation ΔQ sends an operation command of the electric control valve V _A. C ₃ is a servo drive circuit to position the valve opening by sending a drive output to the control command and an electric control valve electric control valve based on the opening signal.

The pressure control unit PC performs constant control of the estimated end pressure.
Estimate and calculate the pipeline head loss due to the increase in flow rate, variably control the distribution pressure to correct this head loss, and control so that the terminal pressure is constant. That is configured as the second view, enter the pump discharge flow rate Q ₂ and merging point pressure (end pressure) P _N, the pump starting at _{P N> P 1 -α, P} N> P 1 and Q 2 < at q ₂ and the pump stops (q _2: minimum pump flow rate), the pump P ₁₁ according to the flow rate Q ₂ ..., ..., performs controlling the number of P _1n, in response to the flow rate Q ₂ at the function generator settling and performs pump speed control (speed control) based on the deviation between the presumed terminal pressure and merging point pressure P _N to be.

Next, the operation of this embodiment will be described. First, a description will be given of water distribution control in the case where the water distribution is performed at the basic water distribution amount shown in FIG. When the pressure P _S in converging N is set flow rate Q _S in the corresponding appropriate pressure (correction start pressure) less than P _1, a predetermined flow setpoint Q _S is indicative of the natural flow sewage. That this flow setpoint Q _S is compared in a comparator C ₁ and the flow rate Q ₁ obtained by converting output detected by the provided natural flow waterway flowmeter Q _A flow at a flow rate converter E _Q, the deviation ΔQ There is inputted to the controllers C _2, and sends it to the servo drive circuit C ₃ calculates the operation command for the electric control valve V _a. Servo drive circuit C ₃ is the positioning of the opening drive output to the motor control valve V _A is sent on the basis of the control valve opening signal the operation command and feedback.

On the other hand, the pressure control unit PC for estimating constant end pressure control input of said merging point pressure P _N and distribution pumping water flow rate Q ₂ is performed the number selection of distribution pumps in accordance with the flow rate Q ₂ as described above distribution pump P _11, ..., together with providing a start and stop command to the P _1n, the variable speed control of distribution pumps in operation on the basis of a deviation between the flow rate Q ₂ to generate the settling pressure corresponding the merging point pressure P _N The estimated end pressure at the confluence point N is controlled so as to appropriately cope with a change in the used water amount.

Next, water distribution control in the case of performing water distribution equal to or less than the basic water distribution amount shown in the X section in FIG. 3 will be described. Pump delivery rate pressure P _N is out descent command increases the pump speed of the confluence N and distributed water flow is reduced decreases, and becomes equal to or less than the flow rate q _S, the pressure controller PC sends a stop command to the pump pumps To stop. At the same time, also in the flow rate setting correction unit AQS, corrected set flow rate is corrected according to the correction curve set flow rate Q _S has a drop characteristics
Change to Q _S ′. As described above, the corrected set flow rate Q _S ′ and the flow rate of natural sewage water Q ₁ are compared by the comparator C ₁ , the deviation ΔQ is input to the controller C _2, and an operation command for the electric control valve _{VA is} issued. There is calculated and sent to the servo drive circuit C _3. Positioning of the valve opening corresponding to the control command and the drive output to the motor control valve V _A based on the electric control valve opening signal to be fed back is transmitted corrected set flow rate Q _S 'is performed servo drive circuit C ₃ is .

That is, when the used water amount is smaller than the basic water distribution amount, the water distribution pump on the water treatment plant side is stopped, the constant control of the estimated terminal pressure is not performed, and the natural flow by the corrected flow rate set value according to the rising fluctuation of the junction pressure. Control the flow rate of water and maintain an appropriate water distribution pressure.

H. Effects of the Invention As described above, the present invention relates to a system in which natural flowing sewage and pump pressure water are combined and distributed, and for a basic water distribution amount, the natural flowing sewage is controlled at a constant flow rate using an electric control valve. Fluctuations exceeding the basic water supply are secured by pump pressure water supply by pump number control based on the pump discharge flow rate and the junction pressure and constant end pressure control using variable speed control, and are below the basic water supply. In the case of water distribution, it is a method of stopping the water distribution pump and correcting the set flow rate of natural flow sewage according to the rise of the junction pressure and controlling the flow rate, so that a constant amount of natural flow is maintained while always maintaining the appropriate water distribution pressure It has an excellent effect of securing water and promptly responding to fluctuations in the amount of water used to enable fine adjustment.

[Brief description of the drawings]

FIG. 1 is a block diagram of a water distribution control system according to an embodiment of the present invention, FIG. 2 is a block diagram of a pressure control unit for performing estimated terminal pressure constant control, FIG. It is a block explanatory view of an example water distribution system. Q _A, Q _B ...... flowmeter, V _A ...... electric control valve, P ₁₁ ~P _1n ...... distribution pumps, DC ...... distribution controller, AQS ...... flow rate setting correction unit, Q _S ...... flow setpoint , LC: Flow control unit, PC: Pressure control unit, P ₁ ... Appropriate pressure at the junction (correction start pressure), P ₂
…… Maximum junction pressure, P _N …… Convergence pressure.

Claims (1)

(57) [Claims] 1. A water distribution control system for supplying and distributing clean water by combining pump pressure water based on natural flowing water.
If the supply water supply is equal to or greater than the basic water supply, natural flow down water is secured for the basic water supply by a constant flow control using an electric control valve based on the set flow rate. The pump number control based on the discharge rate and the pump variable speed control that keeps the estimated terminal pressure (or junction pressure) constant are ensured. If the supply water supply amount is less than the basic water supply amount, the water distribution pump is stopped and the junction point is stopped. It is characterized by controlling the flow rate of natural sewage water by an electric control valve based on the set flow rate corrected according to the pressure fluctuation exceeding the appropriate pressure and performing water distribution while maintaining the appropriate junction point pressure according to the supply and distribution amount. Water distribution control method.