JP2000170687A - Controlling device for feed water supply system at start and release of parallel operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce pressure fluctuations generated in a water fed part by judging a water usage amount have been changed to eliminate a checking time of pressure, when the rpm of a pump monotonously decreases or monotonously decreased between a prescribed range from the maximum rpm to the minimum rpm. SOLUTION: When practicing on a feed water device wherein three pumps 4 are operated in parallel, an arithmetic section in a controlling device 12 is allowed to memorize an arbitrary rpm which is less than the maximum rpm and more than the minimum rpm of the pump 4 starting first, and an arbitrary rpm (a first rpm) which is less than the maximum rpm and more than the minimum rpm of the pump 4 starting second. After starting of the pump 4 which should start first, or when the pump rpm is monotonously increased to the maximum rpm of the pump 4 owing to the increase of a water usage amount, except for the pump 4 starting last, the pump 4 operated at a stable speed not more than the first rpm immediately starts the pump 4 of the next starting turn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply facility for supplying water to a building having a large number of demand terminals, such as an apartment house, an office building, and a factory. The present invention relates to control of a water supply device that controls the number of operating pumps and the number of rotations of each pump in accordance with the control and performs constant discharge pressure control or estimated terminal pressure constant control when starting and canceling parallel operation.

[0002]

2. Description of the Related Art Conventionally, when a plurality of pumps are operated in parallel, it is necessary to provide a confirmation time of several seconds in order to prevent chattering when starting and stopping the parallel operation of the pumps. Have been done. That is, as shown in FIG. 6, this is explained by a graph showing a discharge amount and a discharge pressure of a water supply device in which a maximum of three pumps are operated in parallel. A curve showing the relationship between the water supply pressure and the water supply pressure required for the water supply equipment used at the highest point and the pipe resistance, and _{bmax, cmax} , d
_max is a curve showing the relationship between the discharge pressure and the discharge water amount when the pump is operated at the maximum rotation speed of the water supply unit when one, two and three pumps are operated, respectively. For the initiation and release of parallel operation of the pump, the pump to start the second, b _max and a point of intersection slightly stop pressure p _{OF 2} over the starting pressure p _ON2 slightly below the pressure of, the third Similarly, a start pressure p _ON3 and a stop pressure p _OF3 are defined for the pump to be started.

[0003] illustrating a control method when the amount of the thus set to Aru water supply apparatus is changed from Q ₀ to Q _1. At the water volume Q ₀ , the pump started first operates at the highest frequency, and the pump started second operates at a frequency equal to or lower than the maximum rotation speed of the pump. When operating the faucet so as to increase the amount of water to Q _1, to the amount of water F point corresponding to increase the rotational speed of the pump was started in the second. After having reached the point F, the piping path is adapted to be water the amount of water Q ₁ by the operation of the faucet, it does not flow in only the amount of water in the two maximum rotational speed pump, operating point on the curve c _max Is moved in the direction of point G. The pressure at point G is the starting pressure p _ON3 of the third starting pump, and the discharge pressure of the water supply device is 1 to less than this pressure.
After confirming that the pressure has been maintained for 2 seconds, the third pump to be started is started at the minimum rotation speed _dmin of the pump. Thereafter discharge pressure to match the pressure of the H point, and controlling the rotational speed of the pump, to end the process until supplying amount of water Q _1.

Conversely, the control method when the amount of used water changes from Q ₁ to Q ₀ is as follows. In the first the water Q _1, pump the highest frequency to start the second, pump started third are operated at a frequency below the maximum rotational speed of the pump. When the faucet is operated so as to reduce the amount of water to Q _0, the rotation speed of the third started pump is reduced to the amount of water at point F. After reaching the point F, since the pipe resistance is larger than the assumed pipe resistance for the discharge water amount of the two pumps, the operating point of the water supply device moves in the direction of the point J on the curve c _max . The pressure at point J is the stop pressure p _ON3 of the third started pump, and it is confirmed that the discharge pressure of the water supply device has maintained this pressure or more for 1-2 seconds, and then the third started pump is stopped. . The confirmation time at the points G and J is a measure for preventing chattering at the start and stop of the pump whose pressure starts third.

[0005]

SUMMARY OF THE INVENTION As described above,
In the conventional water supply system in which a plurality of pumps are operated in parallel, a check time is provided at point G when the amount of water increases, and at point J when the amount of water decreases. Since the water supply pressure keeps decreasing and continues to increase when the amount of water used decreases, the water supply pressure at the demand destination fluctuates greatly, and there is a disadvantage that the water supply amount does not correctly respond to opening and closing of faucets and the like. SUMMARY OF THE INVENTION It is an object of the present invention to reduce pressure fluctuations generated at a demand destination at the time of starting parallel operation and canceling parallel operation of a pump, and to shorten the time required for shifting.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method of starting and canceling parallel operation of pumps, in which the pump speed is set within a predetermined range up to a maximum speed or a minimum speed. When is monotonically increased or monotonically decreased, the number of operating pumps is increased or decreased to determine that there has been a change in the amount of used water, and the pressure check time is omitted.

The present invention also relates to a water supply system having a plurality of pumps for controlling the number of rotations of a pump and performing a constant discharge pressure control, and simultaneously operates the starting pressure and the stopping pressure of the second and subsequent pumps. For the number of pumps to be started, the first number of revolutions less than the highest number of revolutions and the lowest number of revolutions except for the first and last number of pumps, corresponding to the order of pump startup, except for the pump that starts last. And the first rotation speed, and the second rotation speed is set between the lowest rotation speed and the highest rotation speed in the pump which is started last, and the pump is operated at the first rotation speed or less. Pump
If the pump reaches the maximum rotation speed without deceleration halfway, the pump in the next startup sequence is immediately started at the predetermined minimum rotation speed corresponding to the startup sequence, and the second rotation speed If the pump operating above reaches the minimum number of revolutions of the pump without increasing the speed in the middle, the pump is immediately stopped, and regardless of the number of revolutions initially operated, the other After passing through, if a certain pump reaches the maximum rotation speed of the pump and the discharge pressure becomes equal to or lower than the starting pressure of the next pump, the discharge pressure is maintained at a value equal to or lower than the starting pressure for a predetermined time. After confirming that, the pump in the next starting order is started, and regardless of the number of rotations initially operated, after a lapse of time other than the above, a certain pump reaches the minimum number of rotations of the pump and the discharge pressure is reduced. If the stop pressure exceeds And wherein the stopping the pump after confirming that persists at predetermined time the discharge pressure or more.

Further, the present invention is characterized in that the same method as the control method described in the preceding paragraph is used in a water supply device having a plurality of pumps for performing the estimated terminal pressure constant control.

[0009]

1 and 2, an embodiment of the present invention will be described. FIG. 1 is a graph showing the relationship between the discharge amount and the discharge pressure of a water supply device in which three pumps operate in parallel. The horizontal axis indicates the discharge amount of the water supply device, and the vertical axis indicates the discharge pressure. The reference numerals in the figure are common to those in FIG. FIG. 2 schematically shows a configuration of a water supply device for implementing the control method of the present invention.

[0010] The arithmetic unit of the control unit 12, as a number to be used to control the initiation and release of parallel operation of the pump, two sets of start-up of the same P _ON2 and P _OF2, P _ON3 and P _OF3 the conventional method, in addition to the stop pressure, and any rotational speed b ₁ above the minimum rotational speed b _min is less than the first maximum speed of the pump to start the b _max, the maximum rotational speed of the pump to start the second c _{ma x}
Any rotational speed c ₁ above the minimum rotational speed c _min (first speed) is less than, and greater than the minimum rotational speed c _min pump to start the second, any rotational speed c of less than c _1
2 (second rotational speed) and an arbitrary rotational speed d ₂ (second rotational speed) that is higher than the minimum rotational speed d _min and less than the maximum rotational speed d _{max of the} third starting pump are stored. 4 pumps
Similarly, in the case of a water supply system equipped with more than one pump, together with the pressure to start and release parallelism, except for the pump that is started last, any water within the range of less than the maximum rotation speed and exceeding the minimum rotation speed of each pump Except for the pump that starts last, the first rotation speed is set between the minimum rotation speed of each pump and the first rotation speed except for the pump that starts last. 2nd during maximum speed
Is set and stored.

A description will be given of a method of controlling the pump using the pressure for starting and canceling the parallel operation as described above, and the first and second rotation speeds. Except for the pump that is to be started first or after the pump that is started last, the pump that has been operating stably at or below the first rotation speed has a reduced rotation speed due to an increase in the amount of water used. When the pump speed monotonically increases to the maximum rotation speed of the pump, even if the detected pressure of the pressure detector 9 does not decrease to the starting pressure of the next pump to be started,
Immediately start the next pump in the start sequence. In addition, except for the pump that starts first, the pump that has been operating stably at the second or higher rotation speed, but the rotation speed of the pump monotonically decreases to the minimum rotation speed of the pump due to a decrease in the amount of water used. Stops the pump immediately even if the pressure detected by the pressure detector 9 does not rise to the stop pressure of the pump.
When starting and stopping in this way, no confirmation time is provided by the timer.

[0012] Even if the operating point of the pump before the change in the amount of water used is in the above range, the progress up to the maximum rotation speed or the minimum rotation speed is not monotonically increasing or decreasing, and the first operating point is the second operating point. When the number of rotations exceeds 1 and is equal to or less than the maximum number of rotations, and is less than the number of rotations equal to or less than the minimum number of rotations, the pressure detected by the pressure detector is changed to the next pump by the conventional parallel operation start and release method. After the pressure has decreased to the starting pressure of the first pump or increased to the stop pressure of the pump that has been started last, after the confirmation time by the timer, the next pump is started or the operating pump is stopped.

The control mechanism of the water supply device controlled by the above method will be described with reference to FIGS. FIG. 3 to FIG. 5 are flow charts showing, in a simplified form, the flow of a part of a control program stored in an arithmetic unit in a control device of a water supply device, which is related to control of start and release of control in parallel with rotation speed. It is.

FIG. 3 is a flow chart when the rotation speed of the pump does not change and when the rotation speed of the pump started last is changed to correspond to the amount of water used. The control flow for starting the parallel operation of the pumps is as shown in FIG. 4. In step 201 of FIG.
_max ), and when the detected pressure (PV) of the pressure detector is lower than the target pressure (SV), the process proceeds to step 211 in FIG.

On the other hand, the control flow for canceling the parallel operation is as shown in FIG. 5. In step 301 of FIG. 3, the pump is operating at the minimum rotation speed (N _min ) and S
When PV is higher than V, the process proceeds to step 311 in FIG.
When SV and PV are equal, the discharge amount of the pump is balanced with the water usage amount of the demand destination. Therefore, on the basis of the rotation speed (N ₀ ) at this time, the value of the flag to be used is initialized in step 103 in order to determine the control method when the change of the rotation speed reaches N _max and N _min thereafter. Set to a value.
In the example shown in FIG. 3, the rotational speed at which the SV and PV becomes equal, in the case of N _min or more at the first rotation speed (N ₁₎ below, the variable FLG1 to 1, the FLG2 to zero, When the rotation speed is equal to or higher than the second rotation speed (N ₂ ) and equal to or lower than _Nmax , the variable FLG1 is set to 0 and the variable FLG2 is set to 1.

A control flow for starting the parallel operation will be described with reference to FIG. 211 pump was started last in step monotonically increased from the rotational speed between the N _min and N _1, it is determined whether or not reached until N _max of the pump. Determination is performed with the value of FLG1 set when the rotation speed and the amount of water used and the discharge amount are balanced (N _o). The value of FLG1 is shown in FIG.
As shown in step 305, when the deceleration processing of the pump is performed, the value is set to 0. Therefore, when the value of FLG1 is 1, it can be determined that monotonously increases from N ₀ to N _max. And when the pump was driving between N _max and N ₁ reaches up to N _max, when the pump was driving at a rotational speed between the N _min and N ₁ has reached the N _max while repeating increase and decrease 212 Proceeding to a step, the starting pressure (P _ON ) of the next starting pump is compared with the PV. When PV> P _ON , it is determined that the pressure has not reached the value at which the parallel operation is started, and the process returns to step 101 in FIG. 3 to read the PV.

When PV ≦ P _ON , in order to prevent chattering at the time of starting the next pump to be started, after confirming that the pressure equal to or lower than P _ON continues for a certain period of time, in this embodiment, 2 seconds, the next start is performed. Start the pump in order. The control flow from step 212 to step 216 is the same as that of the conventional water supply device of the constant estimated end pressure control and the constant discharge pressure control method. On the other hand, when it is confirmed that the value has monotonically increased to _{Nmax in} step 211, the control flow is configured to proceed to step 216.

Next, the control flow for canceling the parallel operation is shown in FIG.
This will be described with reference to FIG. 311 pump steps N ₂ and N
monotonically decreasing from the rotation speed between _max
Determine if it has reached _min . Determination is performed with the value of FLG2 set in 103 steps according to the value of N _0. F
As shown in step 205 in FIG. 3, the value of LG2 is set to 0 when the speed-up processing of the pump is performed. Therefore, when the value of FLG2 is 1, it can be determined that monotonically decreases from N ₀ to N _min. And when the pump was driving between N _min and N ₂ are led to N _min, also be operated with N ₂ or more, when reached N _min while repeating increase and decrease, the process proceeds to 312 steps, and PV The pump stop pressure (P _OF ) is compared. When PV <P _OF , it is determined that the pressure has not reached the pressure for canceling the parallel operation, and 1 in FIG.
Return to step 01 and read the PV. When PV ≧ P _OF , in order to prevent chattering of the pump, the pump is stopped after confirming that the pressure _{equal to} or higher than P _OF continues for a fixed time, in this embodiment, 2 seconds. The control flow from step 312 to step 316 is the same as that of the conventional water supply device of the constant control method of estimated terminal pressure and discharge pressure. On the other hand, if it is confirmed in step 311 that the value has monotonously decreased to N _min , the control flow is configured to proceed to step 316.

[0019]

According to the control of the water supply device according to the present invention at the time of starting and canceling the parallel operation, a simple increase from a certain amount,
Alternatively, if the amount of water used changes due to a simple decrease and the number of pumps operated is changed to correspond to that amount of water, the number of pumps operated will be changed without taking time between starting and canceling parallel operation. It is possible to provide a water supply device that supplies water with small pressure fluctuations and good responsiveness to an increase or decrease in the amount of use.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a discharge amount and a discharge pressure of a water supply unit performing parallel operation according to the present invention, a curve in which the number of pumps operated and a pump rotation speed are used as parameters, and a resistance curve of a water supply piping system. .

FIG. 2 is a diagram schematically showing a device configuration of a water supply device according to the present invention.

FIG. 3 is a diagram showing a control flowchart according to the present invention.

FIG. 4 is a diagram showing a control flowchart according to the present invention.

FIG. 5 is a diagram showing a control flowchart according to the present invention.

FIG. 6 is a graph showing a relationship between a discharge amount and a discharge pressure of a conventional water supply unit that performs parallel operation, a curve in which the number of pumps operated and a pump rotation speed are used as parameters, and a resistance curve of a water supply piping system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Receiving tank 4 Pump 5 Discharge pipe 6 Discharge side gate valve 7 Check valve 8 Water supply pipe 9 Pressure detector 10 Pressure tank 11 Demand destination 12 Control device 13 Power supply

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3H020 AA05 BA04 BA05 BA15 BA18 CA00 CA01 DA01 DA04 DA22 DA28 EA09 EA10 3H045 AA06 AA09 AA16 AA23 BA02 BA03 BA20 BA23 BA28 BA36 CA03 CA29 DA01 DA05 DA34 DA39 DA41 EA35 EA36

Claims (3)

[Claims] In a water supply device having a plurality of pumps for controlling the number of rotations of a pump, a range in which the number of rotations of the pump is predetermined up to a maximum number of rotations or a minimum number of rotations for starting and canceling the parallel operation of the pumps. In the case of a monotonous increase or decrease during the period, it is determined that there is a change in the amount of used water that needs to be dealt with by increasing or decreasing the number of operating pumps, and the pressure check time is omitted. , A control method at the time of parallel operation start and release of the water supply device. 2. A water supply device comprising a plurality of pumps for controlling the rotation speed of a pump and performing constant discharge pressure control,
In addition to the starting pressure and the stopping pressure of the pumps to be started after the second, the first number of rotations less than the maximum number of rotations corresponding to the starting order of the pumps, excluding the lastly started pump, for the number of pumps operating simultaneously. Except for the number of pumps and the first and last starting pumps, the second number of rotations is between the lowest and the first number of rotations, and for the lastly starting pumps, between the lowest and the highest number of rotations. When each pump is operated at the first rotation speed or less and reaches the maximum rotation speed of the pump without deceleration on the way, the pump in the next start order is immediately changed to the maximum rotation speed. The pump is started at a predetermined minimum rotation speed corresponding to the start order, and immediately when the pump operating at the second rotation speed or more reaches the minimum rotation speed of the pump without increasing speed halfway, Stop the pump and rotate the pump Regardless of whether a certain pump reaches the maximum number of revolutions of the pump and the discharge pressure becomes equal to or lower than the starting pressure of the next pump after a lapse of time other than the above, the discharge pressure for the predetermined time is set to the above-mentioned value. After confirming that the pressure is maintained at a value equal to or less than the starting pressure, the pump in the next starting order is started, and after a lapse of time other than the above, regardless of the number of rotations initially operated, a certain pump starts rotating at the minimum rotation speed of the pump. If the discharge pressure reaches or exceeds the stop pressure of the pump,
A control method for starting and canceling the parallel operation of the water supply device, wherein the pump is stopped after confirming that the discharge pressure is maintained at a value equal to or higher than the discharge pressure for a predetermined time. 3. A water supply system comprising a plurality of pumps for controlling the number of revolutions of a pump and performing constant control of an estimated end pressure, wherein the pumps operating simultaneously with the start pressure and the stop pressure of the second and subsequent pumps are simultaneously operated. For the quantity, corresponding to the starting order of the pumps, except for the pump that starts last, the first number of rotations that is less than the maximum number of rotations, and the minimum number of rotations and the number of rotations that exclude the first and last pumps. The second rotation speed is set between the minimum rotation speed and the maximum rotation speed in the pump that is started last during the rotation speed of the first rotation speed.
When the pump operating at or below the rotation speed reaches the maximum rotation speed of the pump without deceleration on the way, the pump in the next start sequence is immediately determined in advance corresponding to the start sequence. Starting at the minimum rotation speed, if the pump operating at or above the second rotation speed reaches the minimum rotation speed of the pump without increasing speed in the middle, immediately stop the pump,
Regardless of the rotation speed initially operated, if a certain pump reaches the maximum rotation speed of the pump and the discharge pressure becomes equal to or less than the starting pressure of the next pump after a passage other than the above, a predetermined value is set. After confirming that the discharge pressure is maintained at a value equal to or lower than the starting pressure for a period of time, the pump in the next starting order is started, regardless of the number of revolutions initially operated, and after a lapse other than the above, When the pump reaches the minimum number of revolutions of the pump and the discharge pressure becomes higher than the stop pressure of the pump, the pump is stopped after confirming that the discharge pressure is maintained at a value higher than the discharge pressure for a predetermined time. A control method for starting and canceling parallel operation of a water supply device.