JPH0782391B2 - Water distribution system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a system for transmitting water from a pump or a water reservoir installed at a high place to a distant place via a water transmission and distribution pipe by its pressure. A water pressure adjusting control device for controlling the discharge pressure by operating the rotational speed of the pump or the opening of the water pressure adjusting valve to control the secondary side pressure so as to maintain the terminal pressure appropriately, and further the above-mentioned water distribution pipe. The present invention relates to a water transmission and distribution system having a device for detecting pipeline breakage on a road.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional example of a water transmission / distribution system.
In the figure, 1 is a reservoir, 2 is a pressure reducing valve, 3 is a conduit, 4 is a pressure gauge, 6 is a flow meter, 13 is a pressure reducing controller, 20 is a comparison detector, 21 is a division circuit, 22 Is a coefficient calculator, 23 is a pressure deviation detector, and 24 is a flow deviation detector.

In this configuration, water is distributed from the water reservoir 1 installed at a high place to the pipeline system 3 via the pressure reducing valve 2, and the end of the pipeline system 3 is connected to a general household, a factory or the like. A pressure gauge 4 for measuring the secondary pressure of the pressure reducing valve and a flow meter 6 for measuring the flow rate in the pipeline are installed in the pipeline system 3. The pressure reducing valve 2 of the pipeline system 3 is installed to prevent excessive high pressure when the demand amount at night is small. When the pressure becomes excessively high, the amount of water leakage increases and deterioration of the pipeline due to secular change is caused. Therefore, the secondary pressure is controlled by the pressure reducing valve, that is, the pressure reducing controller 13 is installed and the pressure is reduced manually at night by a timer. .

[Problems to be solved by the invention]

In such a method, the operator must constantly change the setting in the case of manual operation, and the timer needs to change the pressure set value according to the demand fluctuation depending on the season and the day of the week. There was a problem of lack of sex.

As a method for solving such a problem, there is a method of controlling the secondary pressure so that the terminal pressure becomes constant.

Generally conduit characteristics is expressed by ^{P = aQ n + Ps (1} ). However, a is a constant determined by the pipe characteristics, Ps is a terminal pressure, and n is a constant indicating the state of pressure decrease with the pipe length, and is usually a constant of 1.8 to 2.0. That is, the above equation (1) shows that the secondary pressure P is determined by the flow rate Q, the terminal pressure Ps, and the conduit characteristics a, n.

For the estimated constant end pressure control, the flow rate Q is measured and the above (1)
This is a method of calculating a secondary pressure set value by calculating the expression with a function calculator. Since the flow rate Q in this method uses the flow rate measurement value, the secondary pressure set value P fluctuates at the flow rate Q, to be exact, to the nth power of Q (n = 1.8 to 2.0) when the flow rate fluctuates significantly. Therefore, there is a drawback that it fluctuates more drastically.

As another method, there is a method of measuring the actual end pressure Pv at a remote place and controlling the secondary pressure from the deviation from the target end pressure Ps, but in reality, a device for measuring the end pressure Pv is required, and Since it is necessary to transmit data by a telemeter method or the like, there are problems such as an increase in price, complexity of the transmission system, and time delay.

By the way, when an abnormality occurs in the pipeline itself during the pressure control of the pipeline, especially when the pipeline system 3 is broken, the pressure control system becomes abnormal. Therefore, the abnormal state of the pipeline is monitored and detected. There is a need. As a method of detecting such pipe breakage,
The one described in Japanese Examined Patent Publication No. 60-25730 is known, which will be described below.

This conventional method is designed to detect a line break by observing a pressure change with respect to a flow rate change.

That is, the above equation (1) is partially differentiated as follows, It is a detection method that constantly monitors the resulting (ΦP / ΦQ), and if the value at that time is smaller than anQ ⁿ⁻¹ , the pipeline is broken.

A more specific description will be given with reference to FIG.

The pressure deviation detector 23 detects the time change P (t) -P (t-Δt) of the secondary pressure P from the pressure gauge 4, and the flow deviation detector 23
24 is a time change amount Q (t) -Q (t of the flow rate Q from the flow meter 6.
-Δt) is detected. In the division circuit 21, {P (t) -P
(T−Δt)} / {Q (t) −Q (t−Δt)} is calculated, which corresponds to the left side (ΦP / ΦQ) of the equation (2). In addition, in the coefficient calculator 22, Q (t
-Δt) is taken out to calculate anQ ^n-1 (t-Δt), which corresponds to the right side (anQ ^n-1 ) of the second equation. In the comparison detection 12, the amounts on the left side and the right side of the equation (2) obtained as described above are compared, and (ΦP / ΦQ) <(anQ ^n-1 ± α) is detected, and it is determined that the pipeline collapses. It should be noted that the reason why α is added is that a certain range may be erroneously determined due to a certain error or noise, so that a certain range is provided to prevent this. In such a conventional method, the slope of the flow rate Q (an
Q ^n-1 ) and time change of pressure / time change of flow rate (ЭP /
However, if combined with the above-mentioned terminal pressure constant control, there are the following problems.

This problem will be described with reference to the characteristic curve of FIG.
In the figure, when the valve is throttled at the end while operating at the P ₁ point at the beginning, the resistance curve is operated from HA to HB, the flow rate at that time changes from Q ₁ to Q ₂ , and the secondary pressure becomes From the specified value (P ₂ −
P ₃ ) higher. In this case, the operation is performed in the direction of lowering the secondary pressure by the constant end pressure control, for example, at a pressure of P ₄ so as to satisfy the end pressure setting Ps. In this way, pressure fluctuation of P ₁ → P ₂ → P ₄ and flow fluctuation of Q ₁ → Q ₂ → Q ₃ occur, especially at the inflection point of P ₂ the change in pressure and flow rate (ЭP / ЭQ Since the polarity of () changes, it is difficult to obtain the amount of this change, which may result in an erroneous determination. In other words, the conventional detection method is good when no control is performed, but when the control is attempted, the above problems occur.

Therefore, the present invention secures an appropriate terminal pressure against fluctuations in the demand amount within a fixed time without relying on an actual terminal pressure measuring telemeter system, etc., and hunts the water pressure adjusting valve against a sudden instantaneous demand amount change. Can be prevented,
Moreover, it is an object of the present invention to provide a water transmission / distribution system capable of preventing erroneous determination of pipeline breakage detection due to a change in the water pressure adjusting valve opening.

[Means for solving problems]

A water pressure adjusting valve, a pressure gauge and a flow meter are arranged in a pipe for transmitting and distributing water from a pump or a water distribution reservoir, and a storage means for storing the amount of water distributed per unit time from the flow meter,
Pattern generating means for generating a basic pattern of water distribution for one day, and first calculating means for calculating a difference predicted value one unit time ahead by Kalman filter method from past data showing a difference value with the actual value of water distribution Second calculation means for calculating the hourly water distribution amount one unit time ahead by adding the basic water distribution pattern one unit time ahead to the difference prediction value, the one unit time ahead water distribution amount prediction value, the terminal pressure target value, and And a third calculating means for calculating the pressure target value from the pipe constant, and the water supply / distribution system for controlling the water pressure adjusting valve based on the pressure target value is obtained via the second calculating means. Fourth computing means for computing a water distribution forecast curve represented by a quadratic curve from one unit time ahead water distribution forecast value and the past two unit hours actual water distribution volume actual values stored in the storage means; Value on the water quantity prediction curve and the flow rate Comparing the flow rate measurement values from, it provided a determining means.

[Operation] The demand amount one unit time ahead is predicted by the calculating means, and the secondary pressure set value of the water pressure adjusting valve or pump that secures an appropriate end pressure against the demand amount fluctuation of the unit time is calculated based on this Then, the water pressure is adjusted and controlled by this secondary pressure setting value, while the predicted flow rate curve is further calculated from the demand amount one unit time ahead, and when the flow rate exceeding a certain range is detected from this predicted curve, the pipe It is determined that the road is destroyed.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, 7 is a basic pattern generator, 8 is a predictive calculator, 9 is a water distribution amount calculator, 10 is a distribution curve calculator, 11 is a water pressure calculator, 12 is a pressure reduction stage calculator, and 14 is a pipeline. Destruction detector, 15 is an alarm setting output device, and the others are the same as in FIG.

That is, the hourly water distribution amount calculator 9 integrates the flow rate from the flow meter 6 in a unit time to create a hourly water distribution pattern for one day. This hourly water distribution pattern is divided into weekdays and holidays,
For example, the data for 5 days is stored, the averaging process for each time zone of the 5 days is performed by the prediction calculator 8, and the results are stored in the basic pattern generator 7 for weekdays and holidays, respectively. Prediction calculator 8, weekdays by calendering, as well as select a holiday patterns, extraction actual time distribution of the past m unit time (q _ti) from the time water distribution amount calculator 9, actual time distribution amount and (q _ti) Basic pattern (
_ti )) and the difference value (Δq _ti ). This difference value (Δq
_{For ti} ), the time water distribution difference predicted value ( _{Δt + 1} ) one unit time ahead is calculated by the well-known Kalman filter method using a linear model formula such as the following formula (3).

Here, a _i is a prediction coefficient, and the Kalman filter method is used to sequentially adaptively correct a _i so that the variance of the prediction error (Δ _t −Δq _t ) is minimized. Δ from the above equation (3)
_{t + 1} is calculated and added to the basic pattern (q _{t + 1} ) by the hourly water distribution calculator 9 to calculate the hourly water distribution 1 unit time ahead (
_{t + 1} ) is calculated. The water pressure calculator 11 uses this calculated 1
Unit time later distributed water amount predicted value _{(t + 1)} from the following (4) water pressure target value as expression Request _{(t + 1). t + 1} = a. ( _{t + 1} ) ⁿ + b (4) Here, a and n are pipe line characteristics, and b is a required terminal pressure, which is determined by pipe network calculation, as in the equation (1).

On the other hand, it is also possible to determine a and b from the operation record as follows. That is, the normal n = 1 described in the equation (1).
From 8 to 2.0, n = 1.85 is set, and a and b are calculated from the simultaneous equations of the equations (5) and (6) as in the equations (7) and (8).

Pmax = a (Qmax) ^1.85 + b (5) Pmin = a (Qmin) ^1.85 + b (6) In the above formula, Qmax is the maximum flow rate, Qmin is the minimum flow rate, Pmax is the distribution pressure at the maximum flow rate, and Pmin is the distribution pressure at the minimum flow rate, and these values can be obtained from the actual operation values.

On the other hand, the water pressure target value output from the water pressure calculator 11
_The pressure reduction stage selector 12 converts _{t + 1} into a pressure stage value. In this conversion method, as shown in FIG. 2, for example, when the water pressure calculation value _{t + 1} in the time zone of _{t + 1} , the pressure level value P ₄ is output by the rounding up method.

It should be noted that the figure is an example in the case of 8 stages, but it is needless to say that N stages are also possible. Further, the pressure reduction stage selector 12 also has a function of forcibly calculating the pressure value P ₁ for securing the maximum discharge pressure from the fire input signal AL.

As explained above, the demand amount one unit time ahead is predicted,
By controlling the pressure stage based on this predicted flow rate, the drawback of pressure control fluctuations associated with fluctuations in the flow rate measurement value Q of the conventional method can be eliminated, and the actual terminal pressure Pv at a remote location can be measured. It is not necessary to use a device and a telemeter that operate, and the pressure reduction stage selector 12 makes it possible to easily meet the demand pressure at the time of a fire.

Next, a method for detecting the breakage of the conduit will be described.

The conventional method is to detect from the correlation equation of the pressure change and the flow rate change with respect to the flow rate change.When combined with the constant end pressure control method, the pressure is controlled against the demand pressure fluctuation, so the detection accuracy deteriorates due to control interference, and eventually the error occurs. The possibility of detection is as described above. In other words, in FIG. 6, when changing from Q ₁ to Q ₂ and changing to Q ₃ by pressure control, if it changes from P ₁ → P ₃ → P ₄ like the D line, the conventional detection method may be used, Actually, it changes from P ₁ → P ₂ → P ₄ , so
The conventional detection method based on tilt may cause false detection at P ₂ . Therefore, in the present invention, focusing only on the flow rate fluctuation, a highly accurate demand forecast is obtained, and when the flow rate forecast curve deviates greatly, the pipeline breakage is detected to prevent erroneous detection due to pressure control interference.

This point will be described more concretely.

The distribution amount predicting curve calculator 10 calculates the water distribution predicted value ( _{t + 1} ) calculated by the time distribution amount calculator 1 for one unit time ahead, and, for example, the hourly distribution amount (qt), (q _t for the past two unit times). _-1 and the following processing is performed: Now, assuming that the prediction curve is a quadratic curve as shown in Fig. 3 (a) and (b), _{t + 1} , qt, q
_The following relation holds for _t-1 .

q _t-1 = ax ₁ ² + bx ₁ + c (9) qt = ax ₂ ² + bx ₂ + c (10) _{t + 1} = ax ₃ ² + bx ₃ + c (11) Here, X ₁ Is the midpoint (point corresponding to y ₁ in Fig. 3) of the time zone [t-2, t-1] of the hourly water distribution qt _-1 from the past 2 unit hours ago to the x ₂ past One unit time ago to the present time, the midpoint of the time zone [t-1, t] of the water distribution qt (point corresponding to y ₂ in Fig. ₃ ), x ₃ is the time one unit time ahead of the present time It is an intermediate point (point corresponding to y ₃ in FIG. 3) in the time zone [t, t + 1] of the predicted water distribution _{t + 1} . Here, the unit time is K
X ₁ in the above equations (9), (10), (11)
Solving the simultaneous ternary equations with = 0, x ₂ = K, x ₃ = 2K, a, b, c can be obtained as in the following equation.

c = q _t-1 (14) Since the above equations (12), (13), and (14) are x ₁ = 0, x ₂ = K, x ₃ = 2K, the current time is N minutes from Therefore, the water distribution predicted value n minutes ahead ( _n can be obtained by the following equation.

In the pipeline breakage detector 14, the distribution amount prediction curve calculator 10
The predicted value ( _n ) of the drainage amount calculated by the above is compared with the flow rate measurement value q _n from the flow meter 6, and when the following expression is satisfied, it is detected as a pipeline failure.

_{q n> n + (α ×} n / 100) ...... (16) q n <n + (β × n / 100) ...... (17) However, alpha is for daytime such as shown in FIG. 4 (b) The dead band width (%) and β are the dead band width (%) for night as shown in Fig. 4 (b). The alarm setting output device 15 sets α and β and the day and night time zones. I can do it. The sampling time for the pipe breakage detection check calculated above is about 1 minute. Also, if the fire input signal AL is input, it will not be detected. Furthermore, continuous m
When the above expressions (16) and (17) are satisfied for a minute, an alarm is output via the alarm output device 15.

〔The invention's effect〕

According to the present invention, the terminal pressure is estimated from the predicted value of water distribution amount per unit time, and the terminal pressure is secured to the rapid fluctuation of the demand amount per unit time by controlling the water pressure adjustment of the pressure reducing valve, and the second It is possible to prevent unnecessary pressure control such as hunting against sudden demand and pressure fluctuation in minutes. Further, since a remote actual terminal pressure measuring device, a telemeter device, etc. are not required, there is an effect that the device configuration can be simplified and the cost can be reduced. Further, in detecting the pipe breakage, the distribution amount prediction curve in units of minutes is obtained, and the detection method is based on the deviation from the flow rate measurement value. Therefore, it is possible to prevent interference noise due to the water pressure adjustment control.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a water pressure adjustment monitoring control system according to the present invention, FIG. 2 is an explanatory view for explaining a selection method in a pressure stage selector, and FIG. 3 is a time water distribution prediction in the present invention. FIG. 4 is an explanatory view for explaining a method for obtaining a water distribution prediction curve for each minute from a value, FIG. 4 is an explanatory view for explaining a pipeline breakage detection method according to the present invention, and FIG. 5 is a conventional pipeline pressure. FIG. 6 is a characteristic diagram of the pump and the pipeline when the terminal pressure constant control is performed by controlling the rotation speed of the pump. Explanation of symbols 1 ... Reservoir, 2 ... Pressure reducing valve, 3 ... Pipe line, 4 ... Pressure gauge, 6 ... Flowmeter, 7 ... Basic pattern generator, 8 ...
Prediction calculator, 9 …… hourly water distribution calculator, 10 …… water distribution curve calculator, 11 …… water pressure calculator, 12 …… pressure reduction stage selector, 13
...... Decompression controller, 14 ...... Pipe breakage detector, 15 …… Alarm setting output device, 20 …… Comparison detector, 21 …… Division circuit, 22 ……
Coefficient calculator, 23 ... pressure deviation detector, 24 ... flow deviation detector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichi Sasaki 1 Fujimachi, Hino-shi, Tokyo, inside Fuji Huacom Control Co., Ltd. (72) Inventor Kenichi Kuroya 1 Fujimachi, Hino-shi, Tokyo Inside Fuji Huacom Control Co., Ltd. ( 56) References JP 56-41499 (JP, A) JP 55-143613 (JP, A) JP 60-25730 (JP, B1)

Claims (1)

[Claims] 1. A storage means for arranging a water pressure adjusting valve, a pressure gauge and a flow meter in a pipe for transmitting and distributing water from a pump or a water distribution reservoir, and a storage means for storing an hourly water distribution amount per unit time from the flow meter. Pattern generating means for generating a basic pattern of water distribution for one day, and first calculating means for calculating a difference prediction value one unit time ahead by the Kalman filter method from past data indicating a difference value with the actual value of water distribution And second calculation means for calculating a water distribution amount one unit time ahead by adding a basic water distribution pattern one unit time ahead to the difference prediction value, and one unit time ahead water distribution amount prediction value and end pressure target value And a third calculating means for calculating a pressure target value from the pipe constant, and in the water distribution system for controlling the water pressure adjusting valve based on the pressure target value, the third calculating means is provided via the second calculating means. One unit time ahead Fourth calculating means for calculating a distribution quantity prediction curve represented by a quadratic curve from the distribution quantity prediction value and the hourly distribution quantity actual value of the past two unit hours stored in the storage means, and on the distribution quantity prediction curve And a flow rate measurement value from the flow meter, for determining and comparing the flow rate measurement value and the flow rate measurement value, and detecting the pipeline breakage from the determination result.