JPH05231332A - Liquid supply device - Google Patents

Abstract

PURPOSE:To prevent the pressure fluctuation in starting, stopping and switching by controlling a plurality of motors to drive a plurality of pumps by means of a plurality of inverters and by starting and operating one of the inverters, when the other one is tripped, at the same speed as the other one. CONSTITUTION:Two pumps 8 and 9 are connected to a water main in parallel through a gate valve 202. In addition, check valves 206 and 207 and gate valves 208 and 209 are connected to the downstreams of the pumps 8 and 9 respectively, to which a water supply pipe 213 is joined at their downstreams. In addition, to the water supply pipe 213 a pressure tank 210 and a pressure sensor 211 generating pressure signals are connected. On the other hand, a controller 214, in which pressure signals are input is installed, has a built-in inverters to drive the motors IM1 and IM2 of the pumps 8 and 9 and built-in micro computer to control both inverters. In the case where one inverter trips, the other inverter is started and runs at the same speed as the tripped inverter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply device using a plurality of inverters.

[0002]

2. Description of the Related Art A conventional water supply system using an inverter uses a backup system as shown in FIG. 17 because the inverter is expensive. That is, when the pump 8 is driven by the inverter drive, first, the electromagnetic contactors 1, 3
To operate the inverter INV by outputting the operation and speed command signals. After that, when operating the pump 9, 3
At the same time, the inverter operation signal and the speed command signal are reset, the electromagnetic contactor 4 is closed, and the inverter operation signal and the speed command signal are output. By the way, the inverter may trip in order to protect from fluctuations in power supply and overload. In case of a trip, Japanese Patent Application Sho 58
-62131, it supplies water by switching to a commercial power source for operation.

Further, when the two units are operated at the same time due to insufficient usage, for example, when the pump 8 is in the variable speed operation by the inverter, the electromagnetic contactor 5 is turned on to start the pump 9 to operate in parallel. do. Furthermore, when disconnecting the pumps operated in parallel, the following constant speed pumps 8 or 9 are stopped. As a conventional technique of this, Japanese Patent Application No. 57-1623
There are 26.

[0004]

In the above-mentioned prior art, the pump is once stopped when the amount of water used is small, such as at night, but when the pump is stopped, as shown in FIG.
7, in the example of the constant discharge pressure control method, the pressure tank 210 is not filled with water because the pressure is normally constant. If it is determined that the control system should be stopped although not shown in the figure, the pressure tank 2
In order to fill 10 with water, from NMIN shown in FIG.
Increase the operating speed of the pump to NST and stop it. Therefore, under the worst condition of the water supply pressure, the pressure is increased to H4. Further, when starting and stopping the second (constant speed) pump, the parallel starting pressure is H2 and the parallel stopping pressure is H1, so pressure fluctuations may occur, which may adversely affect the equipment used.

On the other hand, with the recent remarkable technological progress,
The price of the inverter has been reduced, and it has become popular in various fields.

In view of the above, the present invention has an object of having one inverter for one pump, jumping to the other when the inverter fails, and eliminating pressure fluctuations at the time of starting, stopping or switching. To do.

[0007]

In order to achieve the above object, one inverter is provided for one pump. Then, the speed command to the inverter is commanded according to each pump.

1. If one inverter trips,
The other inverter starts up and runs the pump at the same speed as the tripped inverter.

2. When stopping the pump when the amount of water is small (the amount of water used is small), the speed command of the inverter is set to an extremely low speed and the other is started at the same speed. After this, the inverter pump that was operating earlier is stopped and switched. Furthermore, in order to suppress the wear of the electromagnetic contactor, the inverter of the preceding machine should be instructed to stop (speed 0 command), and the primary electromagnetic contactor of the inverter should be ready for operation immediately until it is turned on. I'll do it. Then, when the water supply pressure falls below the specified value, the inverter is speed-instructed to start.

3. When increasing the number of pumps and following the second pump, start the other one from the minimum speed and wait before one reaches the maximum speed, and when one reaches the maximum speed, the follower is predetermined Try to increase from the lowest speed. Two
When one pump is removed from the stand operation, both pumps reach the maximum speed, then the follower machine fixes the speed, and gradually reduces the speed of the preceding machine until the minimum speed is reached. If it becomes higher, stop the preceding aircraft.

[0011]

[Operation] The pump pressurizes the water in the main water pipe or pumps the water in the receiving tank and sends it to the demand end. The pressure sensor is attached to the water pipe and emits a pressure signal according to the pressure here. One inverter is provided for each pump, and the operation command is given as follows so that the speed command and the operation command can be independently issued.

1) When one inverter trips, the inverter pump is stopped at the tripped speed and the pressure drop is suppressed to the minimum time.

2) When stopping due to use of a small amount of water, when the water supply pressure is at the specified value, the operation is performed at an extremely low speed, eliminating waste of power, and when stopping and switching one, start the other at the same low speed in advance. The pressure fluctuation is reduced by stopping and switching when the pressure exceeds the specified pressure.

3) Inverter operating when increasing speed. Before the pump reaches the maximum speed, the pump to be increased is started and fixed at Nmin in advance so that the preceding pump reaches the maximum speed. When the pressure drops below the specified pressure, the boost pump that is operating at a fixed speed is accelerated, and when both deceleration and deceleration reach 100% N, the follower is fixed at 100% N, The pressure fluctuation is minimized by decelerating to Nmin and stopping it when it reaches or exceeds the specified value.

[0015]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 16.

A first embodiment of the present invention will be described with reference to FIGS.

Recently, as shown in FIG. 1 and FIG. 2, the water supply device has begun to be used by directly connecting it to a water main.
In this case, since a plurality of the same devices are installed in the mains of the water supply, there is a concern that the pressure fluctuations caused by starting and stopping the pump may affect the mains.

Therefore, in this embodiment, the pressure fluctuations are minimized, so that a water supply apparatus which does not have an adverse effect due to the pressure fluctuations even if it is directly connected to the water mains and used.

FIG. 1 is a block diagram of the liquid supply apparatus of this embodiment, in which stainless steel pumps 8 and 9 are connected in parallel to a water main via a partition valve 202. Downstream of the pumps 8 and 9, check valves 206 and 207 and a gate valve 208,
209 are connected to each other, water supply pipes are joined downstream thereof, and a pressure tank (or a diaphragm tank) 210 having an air reservoir inside the joined water supply pipes 213, a pressure sensor for issuing a pressure signal in accordance with the pressure here 211 is connected.

Reference numeral 214 is a control device for the pumps 8 and 9,
A control circuit including an inverter that drives the motors IM1 and IM2 of the pumps 8 and 9 and a microcomputer that controls the inverter is built in.

Further, the water supply device of this embodiment is housed in a compact package as shown in FIG. 12 so that it can be easily handled.

FIG. 3 shows a power circuit of the controller of this embodiment, PW is a power source, 401 is a wiring breaker, and 402a, 40.
3a is the first pump 204 and the second pump 20 respectively
5, main circuit contacts of the electromagnetic contactor, 404, 405 are inverters for driving respective pumps, N1, N2
As will be described later, are signals for instructing the speed of the inverter, and 406 and 407 are signals for the same operation command.

Similarly, FIG. 4 shows a control circuit of the control device, in which 501 is a switch for turning on and off, 502 is a stabilizing power source composed of a transformer, a diode bridge, a regulator and the like, 509 is a microcomputer (hereinafter,
It is abbreviated as a microcomputer. ) Is a power supply terminal for supplying the power source to the above), and 503 is an interface for controlling opening / closing of the electromagnetic contactors 402, 403 and relays 406, 407.

When the electromagnetic contactors 402 and 403 are turned on, their contacts, that is, the contacts 402a and 403a shown in FIG. 3 are closed. Similarly, when the relays 406 and 407 are excited, their contacts 406a and 407a are closed.

Reference numerals 510 and 511 denote central processing units 5.
Inverters 404, 405, such as N
An interface for commanding speeds of 1 and N2, and is composed of a D / A converter or the like.

Reference numeral 518 will be described later, but as shown in FIG. 5, a target value for controlling the pressure in a predetermined relationship, for example, H
A switch for setting 0 and H1, which is taken into the CPU via the interface 512. Similarly, 519
Is a switch for setting a speed point for switching from a speed change command, which is a predetermined command speed, to a fixed speed command or vice versa.
Incorporated into the CPU via 6. Further, 520 is an interface for taking in the pressure signal of the water supply pipe detected by the pressure sensor 521, and the port 517 constitutes the controller 530.

FIG. 5 shows a diagram illustrating the operating characteristics of the pump when the terminal pressure constant control is performed, and the same reference numerals as those in FIG. 18 have the same meaning. Reference numeral 605 is a resistance curve of a pipe or the like, and reference numerals 601 to 604 are operation speeds when the amount of water used changes, the maximum speeds Nmax, N1 and Nmi, respectively.
n. ． ． ． The intersection of the Q-H performance curve and the resistance curve when it is hypothesized is shown.

The operation of the above-structured one will be described. In FIGS. 1 and 5, the pressure in the water supply pipe (the pressure tank is also at approximately the same pressure) is higher than H3 (here, the starting pressure), and the pumps are both stopped. I shall. At this time, the wiring breaker 401 shown in FIGS. 3 and 4 is turned on, the switch 501 is closed, the control device is activated, and the standby state is assumed. Of course, H
Switch 5 for data such as 0, H1, H3, N1, N2
Read from 18 and 519 and store in memory (7
01 step).

When the water tap at the demand end (not shown) is opened, the water supply pressure drops. This is detected by the pressure sensor 521. (Step 702) As a result, if the pressure detected by the pressure sensor 521 is lower than the starting pressure H3 set by the switch, the control device, for example, the electromagnetic contactor 50.
4, the signal to turn on the relay 506 is the interface 5
03 to 515, and 510 to output a speed command signal N1. As a result, one pump 20
4 starts.

Upon starting, the pump will move to point 60 in FIG.
I am driving at 4. When the usage amount increases, the operation is continued along the resistance curve 605, but when the usage amount is small, the operation speed is gradually reduced to continue the low speed NMIN operation (70
3 steps).

If this state is continued for a certain period of time, it shifts to the standby state of the extremely low speed NMIN in step 704. After this, after timing for a certain period of time in 705 steps, it is confirmed in 706 steps whether the pressure is below H0, and if it becomes below, the speed is NMIN (step 707).
To 703 and execute again from step 703.

If the state is H0 or higher, the controller outputs a signal for turning on the electromagnetic contactor 403 and the relay 507 to the inverter 503, and the inverter 4
As a signal N2 for commanding a speed to 05, an extremely low speed signal (N
(Speed smaller than MIN) is output. In this state,
Since the operating characteristic curve of the pump is lower than 608, the pump does not work and is in the idling operation, so that the feed water pressure maintains a predetermined pressure (the pressure on the curve 605). The pump 204 that was operating in advance after a certain period of time
The pump outputs a signal to stop the pump, stops the pump, performs the low speed standby operation of the pump that was operating later, and waits.

When the amount of water used increases and the water supply pressure starts to drop below H0, the speed is increased to correspond to this. When the usage amount further increases, the speed gradually increases. Then, when the operating speed reaches a predetermined N1, the signals 402, 406, 510 for operating the pump at rest at extremely low speeds.
Is output.

Next, the operation for increasing the speed and for increasing the number of the mounts will be described with reference to FIG.

1) The operation speed of the preceding machine is increased from Nmin to N1 and the feed water pressure is lower than the specified value Hi (in order to reliably perform this, a certain period of time is taken and the specified value is truly specified). After confirming the following, it is better to proceed to the next operation.) Then, while increasing the speed toward 100% N, the follower is started within Nmin or less.

2) Thereafter, as the feed water pressure falls below the specified value, the preceding machine continues to accelerate, but the follower machine keeps N speed.
Maintain a speed of min.

Here, the follower is set to Nmin in order to prevent the feed water pressure from rising above the specified pressure which is the target value.

3) In this way, when the preceding machine reaches 100% N and the feed water pressure falls below the specified value H3 even after a certain period of time, the follower is changed from Nmin to 100% N so as to reach the specified value. Instruct to speed up.

Next, the operation during deceleration and reduction of the number of units will be described.

1) When both reach 100% N, the operating speed of the follower is fixed at 100% N.

2) When the water supply pressure becomes higher than the specified value as the amount of water used decreases, the speed of the preceding machine is changed from 100% N to N.
Command to decelerate towards min.

3) Furthermore, if the amount of water used is small, the speed of the preceding machine reaches Nmin, and the water supply pressure becomes higher than the specified value H4 even after a certain period of time, the speed of the preceding machine is made extremely low, and then the preceding machine. To stop.

This is to eliminate the adverse effect of the inverter due to the transient current at the time of stop.

The above operation will be described in more detail with reference to the flow charts of FIGS.

In step 804, it is judged whether the operating speed of the preceding machine has reached Nin. If N1 or less, 801 is determined.
Returning, if N1 or more, proceed to the next step 805 to start the follower at a speed of Nmin or less. And
Maintain this speed.

Then, in step 816, it is determined whether the operating speed of the preceding machine has reached the maximum speed Nmax. If it has, the speed lock of the following machine is released from this point, the speed control is restarted, and the preceding machine is fixed to the maximum speed Nmax (see step 818). In this state, the operating point of the pump is at the point 602 in FIG. 5, so that pressure fluctuation does not occur.

If the operating amount can be covered by one unit, 8
In steps 09 and 810, the operating speed of the preceding machine is detected to determine whether it is the minimum speed Nmin. If the pressure is equal to or lower than Nmin and equal to or higher than the specified pressure, the state is in the vicinity of the point 604 in FIG. Then, the process returns to step 801 and is executed again from here.

Similarly, when the number of vehicles is reduced, the operating speed of the follower is detected in step 822, and the minimum speed Nmi is detected in step 823.
It is determined whether n has been reached. If this result is reached, 8
It is determined in step 26 whether the pressure is equal to or higher than the specified pressure H4. If the result of determination is H4 or more in FIG. 5, the preceding machine is turned off, the operating speed lock of the follower machine is released, the process returns to step 801 and is executed from here.

In this way, when the pump is stopped, the earlier pumps are stopped earlier, so that the operation load can be divided into equal parts.

In the present embodiment, a plurality of pumps operating in the inverter are combined, so that the pressure fluctuation can be suppressed as shown in FIG. 10 (a). It should be noted that FIG. 11B shows a case where the inverter operation and the rated operation are combined, but it shows that a sudden pressure fluctuation occurs when the pump in the rated operation is operated at the time of switching.

In this embodiment, the pressure of the water mains can be used as compared with the current system using a water receiving tank as shown in FIG. 11, so that the pressure of the pump can be small and energy can be saved. ..

Next, an example in which the speed command signal to the inverter is set to one point will be described as a second embodiment with reference to FIG.
Now, it is assumed that the amount of water used is small and the pump 204 is operating with the characteristic curve 609 at the extremely low speed Nmin ′ shown in FIG.

When a state in which the amount of water used is small is detected in this state, the operation signal 407 of the inverter 405 for driving the other pump is turned on, and the same speed command signal N as that of the preceding inverter is output to output both pumps. Operate at extremely low speed. Then, after a certain period of time, the preceding pump is stopped. Even in such a case, it is needless to say that since the pump operation is switched and the pressure is not changed, the speed command signal only needs to be one point, so that the control device can be inexpensively constructed.

The third embodiment of the present invention, which will be described with reference to FIGS. 14 and 15, is a liquid supply device configured to perform backup in the event of a failure of the inverter or pump.

FIG. 14 is a diagram in which an electromagnetic contactor contact for switching at the time of backup is added to FIG. 3, and FIG. 15 is a switching circuit in FIG. 4 for switching the electromagnetic contactor in FIG. The protective thermal relay contacts 522 and 523 and the inverter trip signal contacts 524 and 525 are added. Further, the control device 508 is provided with an input port 521 for inputting these failure signals.

In the thus-configured apparatus, for example, when the inverters INV1 and IM2 fail, the electromagnetic contactors 402 and 403 are released, INV2 is commanded to operate, and IM1 is operated by this inverter to perform backup. ..

Similarly, when INV2 and IM1 fail, the electromagnetic contactors 402 and 403 are released to stop INV2, the electromagnetic contactor 411 is closed, INV1 is commanded to operate IM2, and backup is performed. ..

In this way, reliability is improved without water breakage at the time of failure.

A fourth embodiment of the present invention will be described with reference to FIG.

The present embodiment is the same as the first embodiment except that the water main of the first embodiment is replaced with a water receiving tank.

FIG. 16 is a block diagram of the liquid supply device of this embodiment, in which 201 is a water receiving tank, 202, 203, 208, 209,
212 is a sluice valve, 204 and 205 are pumps driven by inverters respectively, 206 and 207 are check valves, 21
Reference numeral 0 is a pressure tank (may be a diaphragm tank) having an air reservoir inside, 211 is a water supply pipe 213, and is a pressure sensor that emits a pressure signal according to the pressure here. The power circuit of the control device of this embodiment is the same as that of the first embodiment shown in FIG.
PW is a power source, 401 is a wiring breaker, and 402 and 403 are the first pump 20 respectively.
Electromagnetic contactors for Units 4 and 2 pump 205, 404, 40
5 is an inverter that also drives each pump, N
1 and N2 are signals that command the speed of the inverter.
06 and 407 are signals for the same operation command.

[0062]

The present invention has the following effects.

1) When one inverter trips, the inactive inverter pump is started up at the tripped speed, so the pressure drop can be suppressed to the minimum time.

2) When the supply water pressure is at the specified value when stopped due to the use of a small amount of water, it is possible to eliminate waste of power by operating at an extremely low speed, and at the same time, start the other at the same low speed when stopping and switching one. If the pressure exceeds the specified pressure, the pressure change is small because it is stopped and switched.

3) Inverter operating when increasing the speed. Before the pump reaches the maximum speed, the pump to be increased is started and fixed at Nmin in advance so that the preceding pump reaches the maximum speed. When the pressure drops below the specified pressure, the boost pump that is operating at a fixed speed is accelerated, and when both deceleration and deceleration reach 100% N, the follower is fixed at 100% N, Since the pressure is decelerated to Nmin and stopped when it reaches a specified value or more, the pressure fluctuation becomes minimum.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a liquid supply device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a water supply system using the liquid supply device of the present embodiment.

FIG. 3 is a power circuit diagram of the control device of the present embodiment.

FIG. 4 is a control circuit diagram of the present embodiment.

FIG. 5 is an operation characteristic diagram when the operation of constant end pressure control is performed by the liquid supply device of the present embodiment.

FIG. 6 is an operating characteristic diagram showing the operation at the time of increasing the speed and increasing the number of units in the present embodiment.

FIG. 7 is a flow chart showing the operation procedure of the present embodiment.

FIG. 8 is a flow chart showing the operation procedure of the present embodiment.

FIG. 9 is a flowchart showing the operating procedure of this embodiment.

FIG. 10 is a characteristic diagram illustrating a pressure fluctuation suppressing effect in the present embodiment.

FIG. 11 is a diagram showing an energy saving effect in the present embodiment.

FIG. 12 is a perspective view showing the shape of the liquid supply device of the present embodiment.

FIG. 13 is a power circuit diagram of a control device according to a second embodiment of the present invention.

FIG. 14 is a power circuit diagram of a control device according to a third embodiment of the present invention.

FIG. 15 is a control circuit diagram of the present embodiment.

FIG. 16 is a configuration diagram of a liquid supply device according to a fourth embodiment of the present invention.

FIG. 17 is a control device power circuit diagram of a conventional liquid supply device.

FIG. 18 is an operation characteristic diagram of a conventional liquid supply device.

[Explanation of symbols]

202 and 203 are gate valves, 8 and 9 are pumps, IM1,
IM2 is an electric motor that drives the pumps 8 and 9, 210 is a pressure tank, 211 is a pressure sensor, 401 is a circuit breaker, and 40
2, 403 are electromagnetic contactors, INV1, INV2 are general-purpose inverters, N1, N2 are speed command signals, 406, 407.
Is an inverter operation command signal, 501 is a switch, SW
1, SW2, SW3 are dip switches, 502 is a transformer, 508 is a controller, 503, 510-517.
Is an input / output device, 514 is a memory, 513 is a central processing unit, and 504 to 507 are relays.

Claims (5)

[Claims] 1. A first pump and a second pump which are connected in parallel and whose suction port is directly connected to a water main, and a pressure tank which is connected to a downstream side of the first pump and the second pump. And a pressure sensor, a first electric motor that drives the first pump, and a second motor that drives the second pump.
Motor, a first inverter that controls the first motor, and a second inverter that controls the second motor. If one inverter trips, the other inverter has the same speed as the tripped inverter. A liquid supply device that was started and operated at. 2. The first inverter and the second inverter use a small amount of water, and when stopping the pump, after making the speed of the pump currently in operation extremely low,
The pump which has been stopped is started at the same speed, and when the water supply pressure is equal to or higher than a specified value, the pump that was previously operated is controlled to be stopped.
The liquid supply device described. 3. When the preceding machine is stopped, a stop command (speed 0 command) is issued to the inverter, and the primary side magnetic contactor is kept on standby. The liquid supply device described. 4. When following a second pump, when the preceding pump reaches a predetermined speed before reaching the maximum speed, the following pump is started at the minimum speed and this state is maintained. 2. The liquid supply device according to claim 1, wherein the speed of the follow-up pump is increased from Nmin when the water supply pressure falls below a specified value. 5. When disconnecting from two units to one unit, the follower unit is fixed in this state after both pumps reach the maximum speed, and the preceding unit is maintained each time the water supply pressure becomes higher than the specified value. 2. The liquid supply apparatus according to claim 1, wherein the preceding machine is stopped when the water supply pressure becomes higher than a specified value even after the speed is reduced to reach the minimum speed.