JPH10103250A - Parallel operation of pumps - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a pump device including a plurality of pumps and a pump driving device, which is controlled by a control amount output from one controller, to the outside when the number of operating pumps increases. Reduce disturbances. When a stopped pump device is started in parallel with a running pump device, a controller that outputs a control amount from a sequence control device SC that individually stops the operation of the pump devices PA1, PA2, and the like. A certain water level control device CAA outputs a manipulated variable limit value LMV representing a ratio of the manipulated variable MVB to the primary manipulated variable MVA. The water level control device CAA outputs the manipulated variable MVB by decreasing the value of the primary manipulated variable MVA to a ratio represented by the manipulated variable limit value LMV. The pump devices PA1 and PA2 operate at the discharge amount indicated by the operation amount MVB.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel operation method of pumps driven by a motor controlled at a variable speed.

[0002]

2. Description of the Related Art FIG. 4 shows an example of one pump driven by a motor controlled at a variable speed. In the figure, PP is a pump, MT is a motor for driving the pump PP, MD is a driving device for the motor MT, and C is a controller for controlling the output of the pump PP via the driving device MD and the motor MT. Controller C is the output of pump PP.
A signal MV representing an operation amount to be output by the driving device according to a difference between a set value SV of a target value of a control amount for determining a flow rate of water to be discharged, for example, a water level, and a measured value PV of the control amount. Is a device that outputs In the following description, the measured value PV
Is referred to as a control amount PV. The drive device MD is a device that supplies electric power for giving a rotation speed proportional to the magnitude of the signal MV representing the operation amount to the electric motor MT. That is, through the drive device MD, the controller C can provide the motor MT with a rotation speed corresponding to the value of the signal MV representing the operation amount. The output of the pump PP, which is the output of the pump PP, is the pump
Since the value is uniquely determined by the rotational speed of the PP, the value of the signal MV representing the operation amount is a value that uniquely determines the discharge amount of the pump PP. Therefore, in the following description, the signal MV indicating the operation amount is
Is treated as an operation amount and is expressed as an operation amount MV. The system including the driving device MD, the electric motor MT, and the pump PP can be treated as a device that receives the manipulated variable MV as an input and discharges water at a flow rate corresponding to the manipulated variable MV from the pump PP. As shown in FIG. 4 (b), a single pump device PA that receives a manipulated variable MV output from the controller C and outputs water at a flow rate determined by the manipulated variable MV in a system including the device MD, the motor MT, and the pump PP. Notation.

FIG. 5 shows the relationship between the manipulated variable MV input by the pump device PA shown in FIG. 4 and the flow rate Q discharged by the pump device PA. As shown, when the manipulated variable MV indicates a value of 0%, the manipulated variable MV and the flow rate Q are 0, and the manipulated variable MV is 1
When it becomes 00%, the flow rate Q also becomes substantially proportional to 100%. FIG. 6 is a diagram showing an example of a configuration in a case where pump devices PA1 to PA3 each having the same configuration as the pump device PA shown in FIG. 4 are operated in parallel. In the figure, C1, C2, and C3 are controllers that control the pump devices PA1, PA2, and PA3, respectively, and the SC independently starts and stops the pump devices PA1, PA2, and PA3 via the controllers C1, C2, and C3. Control device for performing sequence control for the operation. Usually, a programmable logic controller is used as the sequence control device SC. The sequence control device SC receives the control amount PV and increases the number of operating pump devices when this value exceeds a predetermined upper limit, and decreases the operating number when the value falls below the lower limit. . The controller Ci (i is the number of the controller C, for example, the controller C1) put into operation by a signal from the sequence controller SC receives the setting signal SV and the measured value PV of the controlled variable, and outputs the manipulated variable MVi.

When the pump units are operated in parallel with respect to the same water source, the respective pump units need only be operated under the same conditions. Therefore, as shown in FIG. Installing a controller is uneconomical. Therefore, in general, as shown in the example of FIG. 7, a common operation signal MV is supplied from one controller C to the pump devices that are operated in parallel, and only the start / stop control is performed from the sequence control device SC. Since the same control amount MV is input from the controller C to the pump devices PA1, PA2, and PA3, the pump devices that have been put into operation by the signal from the sequence control device SC are operated so as to have the same discharge amount. Is done.

FIG. 8 shows an example in which a system including the pump device PA and the controller C shown in FIG. 4 is applied to a water purification system. In the figure, 1 is a sedimentation basin, 2 is a purification tank, PA1, PA2,
PA3 is a pump device having the same configuration as the pump device PA shown in FIG. 4, and is controlled by a water level control device and a sequence control device having a function corresponding to the controller shown in FIG. Water flowing down the basin sewer is first stored in the sand basin 1, and large-particle sand and sludge settle. Pumping equipment PA1, PA2, PA3
The water is discharged to the water purification pond 2 by the above method. Organic matter mixed into the water discharged into the water purification pond 2 is decomposed, and the purified water flows into the main stream of the river. Pump device PAi (i is the pump device PA
The number of operation of the settling basin 1 is indirectly determined by measuring the water level of the basin 1 according to the amount of water flowing into the basin.

FIG. 9 is a block diagram showing a system including a pump PA1 as a representative of the pumps shown in FIG. 8, a sequence controller SC for controlling the pump PA1, and a water level controller CA. In the figure, reference numerals 1 and PA1 denote a sand basin and a pump device, respectively, having the same reference numerals shown in FIG. 8, SC denotes a sequence controller, CA denotes a water level controller, and LS denotes a water level sensor for detecting the water level of the sand basin 1. . The pump devices PA2 and PA3 other than the pump device PA1 shown in FIG. 9 also have the same relationship as the relationship between the pump devices PA1, PA2 and PA3 and the sequence controller SC and the controller C corresponding to the water level controller CA shown in FIG. And the sequence controller SC and water level controller
Controlled by CA.

The operation of the system shown in FIG. 1 will be described with reference to FIG. The water level of the settling basin 1 is converted into a DC voltage by the water level sensor LS, and is input to the sequence controller SC and the water level controller CA as a measured value PV of the control amount. The manipulated variable MV output from the water level control device CA to the pump device PA1 is the pump device PA1 when the measured water level value PV indicates the lower limit L0.
Is proportional to the water level difference based on the lower limit L0 of the water level, so that when the discharge rate of the water level becomes 0% and reaches the upper limit value LM, it becomes 100% corresponding to the prescribed discharge rate of the pump device PA1. Controlled by value. In the sequence controller SC, the water level is the upper limit
If LM is exceeded, it means that the pump unit at that time is operating at 100% discharge amount corresponding to the specified discharge amount and the water level still rises. Start the device. Since the operation amount input to the operating pump device is equal to the operation amount MV supplied to the operating pump device, the operating state is such that the discharge amount is almost 100% when the start is completed. Further, when the water level drops to a water level at which the parallel operation at present is not economical, the sequence controller SC stops the operation of one pump device during the parallel operation. For example, the water level continues to decrease during parallel operation with two units, and the lower limit L0 of the water level is set to 0%, and the upper limit LM
Is stopped when the water level drops to 30% of the water level when the water level is set to 100%.

[0008]

As described above, the pump unit is a pump, a motor for driving the pump, and a drive unit for providing the pump with a discharge amount corresponding to the operation amount by controlling the motor at a variable speed. In a system in which a plurality of pump devices are controlled by a manipulated variable output by a single controller, the number of operating pump devices is 10
If another stopped pump device is started in parallel with the running pump device during operation at a discharge rate of 0%, the started pump device will be 100% under the same operating conditions as the operating pump device. % Will be operated.
Therefore, when the other pump is started when the pump unit operating at 100% output is a single unit, the power is twice supplied from the power supply almost simultaneously with the start, and the application example shown in FIG. In the case of, the discharge from the sand basin immediately doubles, causing a sudden change in the water level, and the disturbance of the sand basin and the water purification basin increases. A sudden change in water level is not desirable because the function of the sedimentation basin and the water purification pond is hindered by excessive disturbance. Further, even for a power system that supplies power to the pump devices, a rapid change in the supplied power is not preferable, although there is power supply equipment sufficient for parallel operation of all the pump devices.

In view of the above circumstances, the present invention provides
A plurality of pump devices including a pump, a motor for driving the pump, and a driving device for providing a discharge amount corresponding to the operation amount to the pump by controlling the motor at a variable speed are controlled by the operation amount output by a single controller. In a controlled system, the present invention relates to a parallel operation method of pumps in which, when a stopped pump device starts, disturbances applied to the outside by the started pump device are reduced.

[0010]

According to the present invention, a pump, an electric motor for driving the pump, and an operation amount are input, and the operation amount is controlled by a variable speed control according to the present invention. A plurality of pump devices, each of which is a device including a driving device that supplies a discharge amount to a pump, a controller that inputs a control amount and a set value as a target value of the control amount and outputs an operation amount, and a pump device are individually provided. When a stopped pump device is started in parallel with one or more operating pump devices in a system including a sequence control device that outputs a signal to start and stop the The controller that outputs the manipulated variable limit value that indicates the ratio of limiting the volume, and the controller to which the manipulated variable limit value is input, starts Until the value is 1, and outputs it reduced to proportions indicated by the operation amount limit operation amount. Accordingly, when the stopped pump device is started by the method of the present invention, the already operated pump device and the started pump device are operated according to the manipulated variable reduced to the ratio indicated by the manipulated variable limit value.

In the present invention, it is preferable that the manipulated variable limit value is increased every time a predetermined time elapses, and is set to 1 at the final time point.

[0012]

FIG. 1 shows an example of an embodiment of the present invention in which the method of the present invention is applied to a water purification plant. In FIG. 1A, reference numeral 1 denotes a sand basin, PA1 and PA2 denote pump devices, and SC denotes a sequence control device having the same functions as those of the same reference numerals shown in FIG. CAA is a water level control device that outputs the manipulated variable MVB,
The pump devices PA1 and PA2 that input the operation amount MVB
Discharge water at the flow rate corresponding to B. Sequence controller
The SC outputs start and stop signals to the pump devices PA1 and PA2, respectively, and outputs the manipulated variable limit value LM to the water level control device CAA.
Output V.

FIG. 1B is a block diagram showing the configuration of the water level control device CAA shown in FIG. 1A. As shown, the water level control device CAA comprises a primary manipulated variable generating circuit CA1 and a manipulated variable limiting circuit CB. Primary manipulated variable generation circuit CA1
Is a circuit having the same function as that of the water level control device CA shown in FIG. 9, and has a lower limit L0 of the water level of the sand basin 1 as the set value SV.
And the upper limit value LM are given as the set value SV of the reference water level, and the measured value PV of the water level is input as the control amount, and the discharge amount of the pump devices PA1 and PA2 is changed to the lower limit value L0 of the water level. Is 0% of the specified discharge amount when the value indicates, and 100% of the specified discharge amount when the upper limit value LM is indicated.
Outputs the primary manipulated variable MVA proportional to the difference between PV and the measured value PV corresponding to the lower limit L0.

The manipulated variable limiting circuit CB receives the primary manipulated variable MVA output from the primary manipulated variable generation circuit CA1, and receives the manipulated variable input from the sequence controller SC (see FIG. 1A). The manipulated variable is the value obtained by multiplying the limit value LMV by the primary manipulated variable MVA.
Output to the pump devices PA1 and PA2 as MVB. The operation amount limit value LMV is a numerical value representing the ratio of the operation amount MVB to the primary operation amount MVA.

FIG. 2 shows the operation amount limit value described with reference to FIG.
LMV is a 2-bit binary number and the operation restriction circuit CB ((b) in FIG. 1)
MVB primary manipulated variable when input to
Shows the ratio to MVA. As shown in FIG. 2, for the manipulated variable limit value LMV of 00,01,10,11, the manipulated variable MVB is 70%, 80
%, 90%, 100%. The ratio of the manipulated variable MVB to the manipulated variable MVA may be different from the example by changing the constant in the manipulated variable limiting circuit CB. If one pump unit is in operation before the stopped pump unit enters parallel operation, it is operating at 100% drainage, and the control level is the water level PV (see (a) in FIG. 1). Is small, the total discharge amount when the number of parallel operation units is increased is based on the prescribed discharge amount of a single unit, while the operation amount limit value LMV is 00,01,10,11. 140%, 160%, 180%, and 200%.
Further, when the number of operating vehicles increases from two to three under the same conditions as above, they are 210%, 240%, 270%, and 300%. Further changing the discharge amount in multiple steps is performed by controlling the operation amount limit value LMV.
This is possible by increasing the number of digits.

The manipulated variable limit value LMV is increased stepwise every time a predetermined time elapses. FIG. 3 shows an example of a change in the operation limit value LMV. In this example, the time point when the number of operating pump devices increases is set as the time origin, and t1 after 5 minutes elapses
The operation limit value LMV is set to 00 up to the point of time, to 01 until the point of time t2 after 10 minutes, and to 10 until the point of time t3 after 15 minutes. As a result, the manipulated variable MVB is different from the primary manipulated variable MVA at time t1.
Until time t2, 80% until time t2, 90% until time t3, and 100% thereafter.

As described above, in the system in which the pump devices PAi shown in FIG. 1 are operated in parallel, when the stopped pump device is started, the sequence controller SC is controlled by the water level controller CAA (FIG. 1). (See (a)), the operation amount limit value LMV is output, and the water level control device CAA reduces the discharge amount of all the pump devices PAi that are operated in parallel to the ratio indicated by the input operation amount limit value LMV. MV limit value
Since the LMV increases step by step every time a predetermined time elapses and finally reaches 1, it is not possible for each pump device to operate at the discharge rate up to that point when the number of parallel pump devices increases. In other words, immediately after the increase in the number of parallel units, the discharge amount of each pump device is restricted, and the restriction on the discharge amount is removed stepwise as a predetermined time elapses.

[0018]

As described above, according to the present invention, a pump, a motor for driving the pump, and an operation amount are input, and the motor is controlled at a variable speed to provide a discharge amount corresponding to the operation amount to the pump. A plurality of pump devices, which are devices including a device, and a controller that outputs a manipulated variable by inputting a control amount and a set value as a target value of the control amount,
In a system including a sequence control device that outputs a signal for individually starting and stopping the pump devices, in a case where the stopped pump device is started in parallel with one or more operating pump devices, the sequence is sent to the controller. The control device outputs an operation amount limit value indicating a ratio for restricting the operation amount. Then, the controller to which the operation amount limit value has been input reduces the operation amount to the ratio indicated by the operation amount limit value and outputs the operation amount limit value from when the operation amount limit value is input until the operation amount limit value becomes 1. I do.

Therefore, by setting the manipulated variable limit value to an appropriate value for the operation of the system including the pump device to be started, the shock applied to the system by the started pump device can be reduced, and the entire system can be reduced. You can drive smoothly. According to the method of the second aspect of the present invention,
In the present invention, the operation amount limit value is increased each time a predetermined time elapses, and is set to 1 at the final time point. That is, since the operation amount limit value increases each time a predetermined time elapses, the restriction on the operation amount by the operation amount limit value is relaxed each time the predetermined time elapses. As the restriction on the operation amount is relaxed, the restriction on the drainage amount of the pump device is also gradually reduced.Therefore, by selecting the change in the operation amount limit value to the number of steps and steps that match the characteristics of the system, It is possible to shift to the normal operation while keeping the disturbance of the system including the pump device accompanying the increase in the number of parallel units within the range permitted by the system.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a system for parallel operation of a pump to which a method of the present invention is applied, which is an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an operation amount limit value and a discharge amount of a pump device in the pump parallel operation system shown in FIG.

FIG. 3 is a diagram showing an example of a change in an operation amount limit value from a point in time when the number of parallel pump units is increased in the pump parallel operation system shown in FIG. 1;

FIG. 4 is a diagram showing an example of a system including one pump device and a controller.

FIG. 5 is a diagram showing an example of a relationship between an operation amount and a discharge amount in the pump device.

FIG. 6 is a block diagram of an example of a system including a plurality of pump devices.

FIG. 7 is a block diagram of another example of a system including a plurality of pump devices.

FIG. 8 is a diagram showing an application example of a system including a plurality of pump devices.

FIG. 9 is a detailed explanatory diagram of the application example shown in FIG. 8;

[Description of Signs] 1 Settling basin LS1 Water level sensor L0 Lower limit water level LM Upper limit water level PA1, PA2 Pump device SC Sequence control device CAA Water level control device PV Water level measurement value signal SV Set value LMV Operation amount limit value MVB Operation amount CA1 Primary Control input generation circuit CB Control input limit circuit MVA Primary control input

Claims (2)

[Claims] 1. A pump device comprising: a pump; a motor for driving the pump; and a driving device for inputting an operation amount and performing variable speed control of the motor to give a discharge amount corresponding to the operation amount to the pump. In a system including a plurality of units, a controller that receives a control amount and a set value as a target value of the control amount and outputs an operation amount, and a sequence control device that outputs a signal for individually starting and stopping the pump device, When starting one pump device in parallel with one or more operating pump devices, the sequence control device outputs to the controller a manipulated variable limit value indicating the ratio of limiting the manipulated variable, The controller whose value has been input changes the operation amount to the ratio indicated by the operation amount limit value from the time the operation amount limit value is input until the operation amount limit value becomes 1. A parallel operation method of pumps, wherein the output is reduced. 2. A parallel operation method for a pump according to claim 1, wherein the operation amount limit value is increased every time a predetermined time elapses, and is set to 1 at a final time point. .