JPH04308377A - Pump driving motor power system switching control device - Google Patents

Abstract

PURPOSE:To prevent the operation continuation of VVVF devices from becoming difficult by shutoff operation by providing VVVF device stop means for stopping the VVVF devices by pump commercial by-pass switching condition formation judging means, and a breaker closing action means for performing the closing action of the breakers. CONSTITUTION:When failure is generated to either one of VVVF devices 5a-5c, a power system switching control device 10 switches the system to the VVVF device into commercial by-pass systems 9a-9c and controls in such a way that all the systems deliver a fluid stably after the specified time. The control device 10 delays the input timing of commercial by-pass breakers 8a-8c for performing changeover into the commercial by-pass systems 9a-9c and gradually raises the frequency of the VVVF devices 5a-5c of the other systems so as to provide three pumps 2a-2c with the rotation speed based on the frequency of the commercial system. The sudden change of the total flow can be thereby prevented without causing the shutoff of the pumps due to the operation of a check valve or the sudden load decrease of the VVVF devices.

Description

[Detailed description of the invention]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pump drive motor power supply system switching control device for switching power supply systems of pump drive motors arranged in a plurality of parallel-connected flow paths.

0002

2. Description of the Related Art Generally, a plurality of fluid delivery systems connected in parallel are used for reasons such as economic reasons, where it is better to provide a plurality of small-capacity systems rather than one large-capacity system.

FIG. 5 shows a system diagram of this type of fluid delivery system.

[0004] Each branch path 1a branches into three from the main flow path 1.
, 1b, 1c are equipped with pumps 2a, 2b, 2c, and are adapted to join the main flow path 1 again. Check valves 3a, 3b, 3c are provided on the outlet side of each pump 2a, 2b, 2c.
is located. In such a system, since it is necessary to equalize the discharge pressures of the pumps 2a, 2b, and 2c, the rotational speed is controlled so that the rotational speeds of the pumps 2a, 2b, and 2c during operation are made the same. In the delivery system as shown in FIG. 5, for example, if the rotation speed of one pump 2a decreases, the discharge pressure of pump 2a will be lower than that of the other pumps 2b and 2c, so the discharge pressure on the downstream side of the check valve 3a will decrease. This is because the pressure increases and the check valve 3a closes.

By the way, the three pumps 2a, 2b,
One of the pumps 2c, 2a, will be explained. As shown in FIG. 6, the pump 2a is connected to a drive source.

[0006] Pump 2a is driven by a motor 4a. The motor 4a is supplied with variable frequency and variable voltage from the VVVF device 5a via the main system 6a. Also,
A commercial bypass circuit breaker 8a is connected to the motor 4a from the commercial system 7.
via the commercial bypass system 9a. This commercial bypass system 9a is provided as a backup for the VVVF device 5a, and when the VVVF device 5a fails, the commercial bypass circuit breaker 8a is closed and the motor 4a is driven by the commercial system 7.

The pump drive motor power supply system switching control device described in FIG. 6 is similarly provided in the pumps 2b and 2c of the other systems shown in FIG.

[0008]

However, the above-described pump drive motor power supply system switching control device has the following problems.

For example, pumps 2a, 2b, 2c in operation
A case will be described in which the VVVF device 5a breaks down and one pump 2a is switched to the commercial bypass system 9a.

Since the output frequency of the VVVF device 5a is lower than the frequency of the commercial system 7, when switching to the commercial bypass system 9a, the rotational speed of the pump 2a increases compared to the rotational speed of the other pumps 2b and 2c. As a result, VVVF devices 5b, 5
The discharge pressures of the pumps 2b and 2c, which use the pump 2c as a driving source, are lower than the discharge pressure of the pump 2a. For this reason, the check valves 3b, 3
c is closed, and the flow rate flowing to the pumps 2b and 2c suddenly decreases. Along with this, the torque of the motors that drive the pumps 2b, 2c decreases, so there is a problem that control cannot be continued due to the characteristics of the VVVF devices 5b, 5c.

[0011] Furthermore, when switching to the commercial bypass system 9a, there is a problem in that the total flow rate flowing into the main channel 1 also fluctuates greatly because fluid is temporarily sent out only through the commercial bypass system 9a.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a pump drive motor power supply system switching control device that can smoothly switch the power supply systems of pump drive motors arranged in a plurality of parallel-connected flow paths. purpose.

[Configuration of the invention]

[Means for Solving the Problems] The present invention provides pumps arranged in a plurality of fluid delivery passages connected in parallel, pump drive motors that drive the pumps corresponding to these pumps, and pump drive motors that drive the pumps. Drive power supply means for supplying power to the pump drive motor from either the power supply from the VVVF device or the commercial bypass system power supply via a circuit breaker; In a pump drive motor power supply system switching control device consisting of a switching means for switching between a power supply and a power supply, it is determined whether a condition is satisfied in order to switch any one pump to a commercial bypass system power supply when all of the pumps are driven by a VVVF device. a pump commercial bypass switching condition satisfaction determining means, a VVVF device stopping means for stopping a VVVF device corresponding to a pump to be switched to a commercial system bypass power supply based on the determination of whether the pump commercial bypass switching condition is satisfied; A circuit breaker closing operation means is provided to close the circuit breaker corresponding to the pump to be switched to the commercial bypass system after a predetermined period of time has elapsed after the determination that the commercial bypass switching condition has been satisfied, and the circuit breaker closing operation means is provided to close the circuit breaker corresponding to the pump to be switched to the commercial bypass system after a predetermined period of time has elapsed after the determination that the commercial bypass switching condition has been satisfied. The number of rotations is increased at a predetermined rate of increase up to the same rotation speed as the rated rotation speed of the commercial bypass system.

[0014]

[Operation] With the above configuration, while stopping the VVVF device corresponding to the pump switching to the commercial system bypass power supply,
After a predetermined period of time has elapsed, the circuit breaker corresponding to the pump to be switched to the commercial bypass system is closed. Furthermore, the rotation speed of pumps other than those to be switched to the commercial bypass system is set to VVVF.
The device increases the rotation speed at a predetermined rate to the same as the rated rotation speed of the commercial bypass system. This prevents the rotational speed of the pump that switches to the commercial bypass system from exceeding the rotational speed of pumps other than the pump that switches to the commercial bypass system. Therefore, it is possible to prevent a sudden decrease in the load on the VVVF device or a sudden change in the flow rate due to shutoff of the pump.

[0015]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram of a pump drive motor power supply system switching control device showing an embodiment of the present invention. The same reference numerals as in FIGS. 5 and 6 indicate the same or equivalent parts.

In this embodiment, a power system switching control device 10, control lines 11a, 11b, 11c and control lines 12a,
12b and 12c are newly provided. The power system switching control device 10 includes any of the VVVF devices 5a, 5b, 5
When a failure occurs in VVVF device c, the system for that VVVF device is switched to the commercial bypass system, and furthermore, the system is controlled so that the entire system stably sends out fluid after a predetermined period of time.

Next, the operation of the power system switching control device 10 will be explained with reference to FIG. 2.

First, each VVVF device 5a, 5b, 5c supplies substantially the same variable frequency and variable voltage to the corresponding motor 4a, 4b, 4c during normal operation. Pump 2a, 2
b, 2c are as shown in FIG. 3(A) or FIG. 3(B),
At time t0, the rotational speed N1 is controlled to be approximately the same, and fluid is delivered at approximately the same discharge pressure. In this state, the discharge pressures of the pumps 2a, 2b, and 2c are approximately the same, and the delivery amount is maintained in balance.

For example, when a failure occurs in the VVVF device 5a, the system is switched to a commercial bypass system as follows.

First, the control line 11a is connected from the VVVF device 5a.
A failure signal is input to the power system switching control device 10. In the power system switching control device 10, as shown in FIG.
Based on the failure signal, it is determined whether the commercial bypass switching condition for the pump 2a is met (101).

When the commercial bypass switching condition is satisfied, a stop command is output to the VVVF device 5a of the pump 2a (102). As a result, pump 2a
As shown in FIG. 3(A), the rotation speed suddenly drops from time t1 and becomes close to zero at time t2.

On the other hand, when the commercial bypass switching condition is satisfied,
At the same time, in the delivery system other than switching to the commercial bypass system, the corresponding pumps 2b and 2c are t
The rotation speed N1 from time 1 is gradually increased to N5, and the rated rotation speed N4 of the commercial bypass system is reached at time t4 (103).

Further, at the same time as the commercial bypass switching condition is satisfied, a timer is activated and the commercial bypass circuit breaker 8a of the pump 2a is closed at time t3 after a predetermined time (104) (105)
.

[0025] As a result, the power supply of the motor 4a is switched by the commercial bypass system 9a, so that the pump 2a is switched from the time t3.
The rotation speed increases rapidly and becomes the rated rotation speed N4 of the commercial bypass system.

In this manner, the three pumps 2a, 2b, and 2c rotate at the rated rotational speed of the commercial system 7, and deliver fluid in a well-balanced manner at approximately the same discharge pressure.

As described above, the timing of turning on the commercial bypass circuit breaker for switching to the commercial bypass system is delayed, and the frequency of the VVVF devices in other systems is gradually increased, and after a predetermined period of time, the three pumps are switched to the frequency of the commercial system. The rotation speed is now based on Therefore, by switching to the commercial bypass as in the past, the rotational speed of the corresponding pump does not exceed the rotational speed of other pumps. Therefore, sudden changes in the total flow rate can be prevented without shutting off the pump or suddenly reducing the load on the VVVF device due to the operation of the check valve.

Next, another embodiment of the present invention will be described with reference to FIG.

When the commercial bypass switching condition for the pump 2a is satisfied (201), the VVVF device 5a is stopped by a stop command (202). Furthermore, the frequency of the VVVF devices 5b, 5c is gradually increased so that the rotation speed of the pumps 2b, 2c becomes the rated rotation speed N4 of the commercial bypass system (
203). When the rotation speed of the pumps 2b and 2c reaches the rated rotation speed N4 of the commercial bypass system, the pump speed increase completion condition is input and the AND condition is satisfied (204), and the commercial bypass circuit breaker 8a of the pump 2a is closed ( 205).

[0030] In the above embodiment, the case where any one of the pumps is switched to the commercial bypass system has been explained, but all pumps can be switched to the commercial bypass system under the condition that any pump is switched to the commercial bypass system. It is also possible to reduce flow rate fluctuations and continue pump operation.

[0031]

As explained above, according to the present invention, when switching one of the pump drive motor power supply systems from the VVVF device to the commercial bypass, the discharge pressure of the pump that continues to be operated by the VVVF device is temporarily reduced. The discharge pressure will not drop below the pump discharge pressure after switching to the commercial power system. Therefore, it is possible to prevent the continued operation of the VVVF device from becoming difficult due to the shut-off operation.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a pump drive motor power supply system switching control device showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the flow of control of the device.

FIG. 3 is an explanatory diagram showing the action of the pump drive motor of the device.

FIG. 4 is an explanatory diagram showing the flow of control of a pump drive motor power supply system switching control device showing another embodiment of the present invention.

FIG. 5 is a system diagram showing multiple parallel connected fluid delivery systems.

FIG. 6 is an explanatory diagram showing a drive source of a pump drive motor.

[Explanation of symbols]

2a, 2b, 2c Pump 4a, 4b, 4c Motor 5a, 5b, 5c VVVF device 8a, 8b, 8
c Commercial bypass circuit breakers 9a, 9b, 9c
Commercial bypass system 10 Power system switching control device

Claims (1)

[Claims] Claim 1: Pumps arranged in a plurality of parallel-connected fluid delivery passages, pump drive motors that drive each pump corresponding to each of these pumps, and a VVVF device that connects these pump drive motors to each other. In the pump drive motor power supply system switching control device that supplies power to the pump drive motor from either the power supply or the commercial bypass system power supply via a circuit breaker, all of the pumps
a pump commercial bypass switching condition satisfaction determining means for determining whether a condition for switching one of the pumps to the commercial bypass system power source while being driven by a VVF device; and a condition satisfaction determining means for pump commercial bypass switching condition establishment determining means. V for stopping the VVVF device corresponding to the pump that switches to the commercial system bypass power supply based on the determination of
VVF device stopping means; and circuit breaker closing operation means for closing a circuit breaker corresponding to the pump to be switched to the commercial bypass system power supply after a predetermined time has elapsed after the determination that the condition is satisfied, and the circuit breaker closing operation means is configured to close the circuit breaker corresponding to the pump to be switched to the commercial bypass system power supply when the commercial bypass switching condition is satisfied. A pump drive motor power supply system switching control device characterized in that the rotational speed of a pump other than the pump to be switched to the commercial bypass system power supply is increased at a predetermined rate of increase to the same rotational speed as the rated rotational speed of the commercial bypass system.