JP3361859B2 - Blower control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the number of blowers and controls the amount of air blown to each blower so that the total amount of blown air matches a target value. And a blower control device that performs feedback control on the blower. 2. Description of the Related Art Conventionally, as in the case of an aeration tank in a sewage treatment plant, for example, by controlling the number of blowers and individually controlling the amount of air blown by each blower, the total amount of blown air is made to coincide with a target value. The blower control device that performs feedback control on the target total air volume Qt as shown in FIG.
If the value exceeds Q2H, start the second blower and
If it becomes 3H or more, the third blower is also activated. Conversely, if the target total air volume Qt becomes less than Q3L during the operation of the third unit, the third blower is stopped, and the two units are operated, and then two more units are operated. When the target total air volume Qt becomes equal to or less than Q2L, the number control is performed such that the second blower is also stopped and one unit is operated. [0003] When the target total air flow rate fluctuates within a range of the number increase / decrease limit value during the operation of a fixed number of blowers, the individual air flow rate is controlled by increasing or decreasing the opening degree of the suction valve of each blower. Feedback control is performed so that the air volume matches the target value. [0004] However, such a conventional blower control device has the following problems. That is, if the target total air volume Qt increases during the operation of the two units and becomes equal to or more than the operation start limit value of the third unit, the third blower is started. However, as shown in FIG.
Then, the suction valves V1 and V2 of each of the two blowers in operation
Is operated in a substantially fully opened state, and the individual air flow rates B11, B1
2, and the third blower is additionally operated with the valve opening degree V3 set in advance to add the individual airflow B13, and the total airflow QSV rapidly increases immediately after the start-up. After that, the feedback control becomes effective, and the suction valve openings V1 and V2 of the two blowers that are already in operation are reduced so that the predetermined target total air volume Qt is obtained. The movement is made to follow the air volume Qt. [0005] Conversely, when a plurality of blowers are operated at the same time and the target total air volume falls below the unit stop limit value and it becomes necessary to stop one blower, the blower is also stopped. There is a time delay until the individual blower volume until just before the blower stops can be covered by another blower, and the total blower volume drops sharply immediately after the blower stops, and the target total blower volume decreases. There was a problem that it took time to match. The present invention has been made in view of such a conventional problem. When a blower to be started for an additional operation or a blower to be stopped for a reduced operation is started or stopped, the blower is not used. Immediately after start-up, the individual air flow is increased in a ramp shape, and immediately before the stop, the individual air flow is reduced in a ramp shape and then stopped. It is an object of the present invention to provide a blower control device which can be stabilized without changing the blower. SUMMARY OF THE INVENTION The present invention is directed to a blower control device that individually controls the number of blowers and the amount of air to be blown, and performs feedback control of the total amount of air to be blown. A required operation number determining unit that determines the required number of blowers to be operated based on the operation number of the blower based on the actual number of blower operation; An air flow distribution calculation unit that calculates an individual air flow target value for each of the operating blowers based on an expression of individual air flow target value = (required total air flow amount−disturbance blower air flow amount) / number of blowers operated; The ramp function generator that generates the disturbed blower air volume of the previous equation as a ramp-shaped function at each stop, and the individual air volume of the blower to be continuously operated to the individual air volume target value of the previous equation Zui controls, in which a separate air volume control unit for controlling, based on a ramp function value which gives the individual blowing rate of the blower as a start or stop target ramp function generator is. In the blower control device according to the present invention, the number of operating units and the amount of air blown by the plurality of blowers are individually controlled. The required number of blowers to be operated is determined based on the air volume, and the operation control unit performs increase / decrease control of the number of blowers to be operated based on the determination result of the required number of operated blowers determination unit. When increasing or decreasing the number of operating blowers, the ramp function generator generates a disturbance blower air flow at startup and at a stop as a ramp-shaped function, and the air flow distribution calculator calculates an individual air flow target value = An operation is performed based on the formula of (required total air flow amount-disturbance blower air flow amount) / number of blowers operated. Then, the individual air volume control unit controls the individual air volume of the blower to be continuously operated based on the individual air volume target value of the preceding equation, and at the same time, the ramp function generation unit determines the individual air volume of the blower to be started or stopped. Control is performed based on the given ramp function value. [0010] In this way, even when the number of blowers operated is increased or decreased, feedback control is performed so as to accurately follow the target total air flow without abruptly changing the total air flow. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a system diagram of one embodiment of the present invention. The blower control device of this embodiment performs feedback control so that the outlet pressure value to the aeration tank matches the target pressure value by controlling the number of three blowers 1. A suction valve 2 for adjusting the individual air flow and an air flow meter 3 for detecting the individual air flow are provided. A discharge pressure gauge 4 is provided on a pipe for combining the air blown from the three blowers 1 and supplying the blown air to the aeration tank. Although the control device 5 is actually constituted by a microcomputer, the functional configuration will be described. The blower discharge pressure target value PSV is compared with the discharge pressure signal PPV from the discharge pressure gauge 4. , A discharge pressure control unit 6 for calculating the blower total air flow amount increase / decrease value ΔQ, and an addition unit 7 for adding the blower total air flow amount increase / decrease value ΔQ to the current blower total air flow amount QSV to obtain a required total air flow amount Qt. I have. The control device 5 also determines the required total air volume Qt,
Based on the current operating number N and a disturbance blower blowing amount d to be described later, an individual blowing amount target value B1 = (required total blowing amount Qt-disturbance blower blowing amount Qd) / blower operating number N .. The air volume distribution calculation unit 8 that performs the calculation based on the equation (1), and the disturbance blower air flow rate Qd of the equation (1) at the time of start-up and stop, respectively, And a ramp function generator 9 that generates a ramp function. Further, the control unit 5 controls the individual air flow rate target value B1 of the blower to be continuously operated and the individual air flow rates B21, B22, B23 detected by the air volume meter 3 obtained by the above equation (1).
, And a valve opening control unit 10 for performing a control ΔV for increasing or decreasing the valve opening of the suction valve 2, and the blower 1 which is an object of the number increase / decrease control.
Operation-start / stop-time control changeover switch 11 that switches to the start / stop state with respect to, and operation-cutoff changeover switch 1
2 is provided. The control device 5 also includes a required number of operating units determining unit 13 for determining the required number of operating units of the blower 1 on the basis of the required total air volume Qt from the adding unit 7, and an operation determined by the required number of operating units 13. Compare the number with the actual number of driving,
A blower operation control unit 14 for controlling the number of operating units is provided. Next, the operation of the blower control device having the above configuration will be described. This blower control device controls the number of three blowers 1 and the opening degree of the suction valve 2 of each blower 1 so that the discharge pressure PPV of the compressed air supplied to the aeration tank always matches the discharge pressure target value PSV. It operates as follows. << Number increase / decrease control >> The discharge pressure gauge 4 detects the discharge pressure PPV of the compressed air to the aeration tank, and the discharge pressure control unit 6 sets the blower discharge pressure target value PSV and the discharge pressure from the discharge pressure gauge 4. Compared with the signal PPV, the total blower air flow rate increase / decrease value ΔQ is calculated and output to the adding unit 7, and the adder unit 7 calculates the blower total air flow amount change value ΔQ as the current blower total air flow amount QSV
To obtain the required total air volume Qt to calculate the air volume distribution calculation unit 8
Is given to the required operation number determination unit 13. As shown in FIG. 2, the required number-of-operations determining unit 13 activates the second blower when the target total air volume Qt exceeds Q2H, and further activates the third blower when the target total airflow Qt exceeds Q3H. Start up, and conversely, the target total air volume Qt
When the following conditions are satisfied, the third blower is stopped and the two blowers are operated, and if the target total air volume Qt becomes less than Q2L during the operation of the second blower, the second blower is also stopped and the single blower is operated. The number of operating units is determined and output to the blower operation control unit 14. The blower operation control unit 14 compares the required operation number with the actual operation number S1 and gives a start command or a stop command to the corresponding blower 1 in order to increase the number by one or reduce the number by one if the number is small, At the same time, when operating the control system of the corresponding blower 1-start / stop control switch 11
To the start / stop side. << During Normal Operation >> At the time of normal operation in which two blowers are in operation and the blower operation controller 14 does not output a command to increase or decrease the number of blowers according to the judgment of the required operation number judging unit 13, The operation-start / stop-time control changeover switch 11 is set to the operation side. In this case, the disturbance blower air volume Qd is 0 in equation (1), and the air volume distribution calculation unit 8 determines the required total air volume Qt from the addition unit 7 and the current operating number signal N from the blower operation control unit 14. = 2, for each of the two blowers 1 in operation, an individual air flow target value B1 = (required total air flow Qt−disturbance blower air flow Qd) / number of blowers N = Qt / 2 And the individual air flow target value B1 is given to each valve opening control unit 10. Therefore, the valve opening control section 10 of each blower 1 compares the individual air flow target value B1 with the individual air flow rates B21, B22, B23 detected by the air flow meter 3, and increases or decreases the valve opening degree of the suction valve 2. The control ΔV is calculated, and in the blower 1 during operation,
The operation-shutoff switch 12 is set to the operation side, and this increase / decrease control signal ΔV is supplied to each suction valve 2 to increase or decrease a predetermined opening degree, and the individual blower amounts B21, B of the blower 1
22 is performed to increase or decrease, thereby controlling the total air flow Qt to increase or decrease so that the discharge pressure PPV coincides with the target value PSV. << At the time of increasing / decreasing the number of operating units >> Now, two blowers are in operation, and the blower operation control unit 14 outputs a command to increase the number of blowers S2 according to the determination by the required operating number determining unit 13. At the time of controlling the number of operating units to be increased, a start command is output to the remaining one blower 1, and at the same time, the operation-start / stop-time control changeover switch 11 of the control system of the corresponding blower 1 is switched to the start / stop state. A command is output, and a command for switching the operation-cutoff switch 12 to the operation side is output. Assuming that the output timing of this command is t0, the ramp function generating circuit 9 is started at this timing t0, and as shown in FIG. 3, the valve is gradually opened from the fully closed state until the valve opening degree Vn becomes constant. A valve opening command signal VLP for increasing the degree is output. However, the valve opening VLP at the timing t0
Is zero, the disturbance blower airflow Qd is 0 in equation (1), and the airflow distribution calculator 8 calculates the required total airflow Qt from the adder 7 and the blower operation controller 14 Based on the current number-of-operated-units signal N = 2, for each of the two blowers 1 in operation, the individual blower amount target value B1 = (required total air amount Qt−disturbance blower air amount Qd) / number of blower units N = The calculation of Qt / 2 is performed, and the individual air flow amount target value B1 is given to each valve opening control unit 10, so that the same valve opening command is given at the time of the normal operation described above. Therefore,
As shown in FIG. 4, the total air flow does not increase sharply at the blower number increase command timing at the timing t0. Thereafter, a signal VLP for gradually increasing the valve opening is output from the ramp function generating circuit 9, and as shown in FIG. 4, the opening V3 of the suction valve 2 of the third blower 1 increases. When the individual air flow rate B23 gradually increases with a constant slope, this becomes the disturbance blower air flow rate Qd, and the air volume distribution calculator 8 calculates the individual air flow target value B1 by the calculation based on the equation (1). = (Required total air flow amount Qt-disturbance blower air flow amount Qd) / number of blowers operated N = (Qt-B23) / 2, and the individual air flow amount target value B1 ( The value obtained by subtracting the disturbance blower air flow rate B23 from the value B1 during the normal operation is reduced by an amount corresponding to the minus value), and the valve opening control unit 10 compares the individual blow air flow rates B21 and B22 with each other. Opening reduction command ΔV is supplied to suction valve 2. To result in the output, two valve opening of the blower 1 of the above is controlled to gradually closing direction as shown by the curve V1, V2 in FIG. 4, finally timing t
1 is the valve opening degree V of the suction valve 2 of each of the three blowers 1
1, V2, and V3 become substantially equal, and accordingly, the individual air flow rates B21, B22, and B23 also substantially coincide with each other, and the total thereof substantially coincides with the required total air flow rate Qt. At the predetermined timing t1, the operation-start / stop-time control changeover switch 11 is returned to the operation control side. Conversely, if the control for reducing the number of blowers to be operated by one is required because the discharge pressure of the compressed air becomes overpressure, the control system of the blower 1 to be reduced is operated. The start / stop control switch 11 is switched to the start / stop state, and the ramp function generation circuit 9 reduces the valve opening command VLP based on the ramp function from the current valve opening to the fully closed state for a certain period of time. The output is supplied to the suction valve 2 of the blower, the valve opening is reduced to the fully closed state within a certain time, and control for finally switching the operation-cutoff switch 12 to the stop side is performed. In this case, assuming that the stop command is given to the third blower at timing t1 so that the time axis shifts from right to left in FIG. 4, the suction valve 2 gradually closes. At the same time, the valve openings of the remaining two blowers 1 are gradually opened so as to cover the target total air volume, and the individual air volumes gradually increase. Finally, the target total air volume is increased by the two blowers 1. The number reduction control is executed so as to send out the air volume. As described above, in the blower control device of this embodiment, when starting or stopping the blower to be started for the additional operation or the blower to be stopped for the reduced operation, immediately after the start of the blower, By increasing the individual air flow rate in a ramp shape and conversely reducing the individual air flow rate to a ramp shape immediately before stopping and then stopping the operation, the total air volume can be changed rapidly when increasing or decreasing the number of operating units. And can be stabilized. It should be noted that the present invention is not limited to the above embodiment, and the ramp function of the blower of the disturbance blower may not be linear. Alternatively, the blower discharge pressure may be kept constant more quickly by changing the required total air flow rate according to whether it is increasing or decreasing. In the above embodiment, the control of the number of three blowers has been described. However, the number of blowers is not particularly limited. Further, the present invention can be applied not only to a blower for blowing air to an aeration tank of a sewage treatment plant, but also to a field in which a strict control of a total blowing amount of a plurality of blowers is required. As described above, according to the present invention, when the number of blowers and the number of blowers are individually controlled, and the feedback control of the total blower amount is performed, the required number of blowers is determined. Determines the required number of blowers to be operated based on the required total air flow, and the operation control unit performs increase / decrease control of the number of blowers operated based on the determination result of the required operation number determination unit. When the ramp function generator starts and stops, the blower blower air flow is generated as a ramp-shaped function, and the air flow distribution calculator calculates the individual air blower target value = (required total air blower−disturbance blower air blower) / Perform the calculation based on the equation of the number of blowers operated, and further control the individual air flow rate of the blower to be continuously operated based on the individual air flow rate target value of the previous equation, and simultaneously start or Since so as to control on the basis of the ramp function value which gives the individual blowing rate of the blower as the stop target ramp function generator is,
Even during the control of increasing or decreasing the number of operating blowers, it is possible to perform feedback control that accurately follows the target total air flow without abruptly changing the total air flow.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram of one embodiment of the present invention. FIG. 2 is an explanatory diagram showing an increase / decrease timing of the number of blowers operated in general blower number control. FIG. 3 is a graph showing an example of a ramp function generated by the ramp function generation circuit in the embodiment. FIG. 4 is a graph showing a change characteristic of a valve opening degree and a blown air amount when controlling the number of blowers operated according to the embodiment. FIG. 5 is a graph showing a change characteristic of a valve opening and a blown air amount at the time of controlling the number of blowers operated according to a conventional example. [Explanation of Signs] 1 Blower 2 Suction valve 3 Ventilation meter 4 Discharge pressure gauge 5 Control device 6 Discharge pressure control unit 7 Addition unit 8 Air flow distribution calculation unit 9 Ramp function generation circuit 10 Valve opening control unit 11 Operation-start-up / Stop-time control changeover switch 12 Operation-cutoff changeover switch 13 Necessary operation number determination unit 14 Blower operation control unit

Claims (1)

(57) [Claims 1] A blower control device that individually controls the number of blowers and the amount of air blown by a plurality of blowers and performs feedback control of the total amount of blown air. A required operation number determining unit that determines the required number of blowers to be operated, an operation control unit that performs increase / decrease control of the number of operating blowers based on the determination result of the required number of operating units, based on the actual number of blower operations, An air volume distribution calculation unit that calculates an individual air volume target value for each of the blowers in operation based on an equation of individual air volume target value = (required total air volume−disturbance blower air volume) / number of blowers operated; A ramp function generator that generates the disturbed blower air volume of the previous equation as a ramp-shaped function at each stop, and controls the individual air volume of the blower to be continuously operated based on the individual air volume target value of the previous equation , Activation or blower control device comprising a separate air volume control unit for controlling based on the individual air blowing amount to the lamp ramp value function generator gives the stop subject to the blower.