JP2024006284A - Feedback control method, program for feedback control and filter system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary filter device control method where load is hardly imposed to a device even when shift to various different operation conditions in treatment capacity is necessary.

SOLUTION: In a feedback control method of a rotary filter device where an endless belt-shaped filter movable by the rotation of a rotor is disposed,: a first parameter set and a second parameter set are previously set as the parameter sets of feedback control; the feedback control using the first parameter set is performed when a predetermined condition on water to be treated flowing in the rotary filter device is not satisfied; and the feedback control using the second parameter set is performed when the predetermined condition is satisfied.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a feedback control method and a program for feedback control used to control a rotary filter device, and a filter system.

A rotary filter device used for sewage treatment, etc. is a device provided in the form of an endless strip filter in which a plurality of panel filters are connected, and by rotating the endless strip filter, it regenerates the filter while regenerating the filter. This is a device that separates solids from treated water. In this type of device, the throughput of the device can be adjusted by adjusting the rotation speed of the endless strip filter.

For example, Japanese Patent Application Laid-Open No. 8-177030 (Patent Document 1) states that when it is detected that the water level has risen to a set water level, the dust remover is operated at high speed and then the operating speed is gradually reduced. , discloses a method of operating a screen movable dust remover that controls the dust remover to stop or operate at a slow speed and stand by when the water level is below a set water level. According to the driving method of Patent Document 1, unnecessary high-speed driving can be avoided.

Japanese Patent Application Publication No. 8-177030

However, in the technology of Patent Document 1, the speed change when switching the operating speed is discontinuous, so for example, if the driving speed changes in a very short period of time, the engagement between the chain and the sprocket will occur. Problems such as misalignment and increased risk of tooth skipping may occur, which may increase the load on rotating equipment such as rotors. Therefore, there was a risk that the life of the rotary filter device would be shortened.

Therefore, it is desired to control a rotary filter device that does not impose a load on the device even when it is necessary to shift to an operating condition with a different processing capacity.

A feedback control method according to the present invention is a feedback control method of a rotary filter device provided with an endless strip filter movable by the rotation of a rotor, wherein the feedback control parameter set includes a first parameter set; When a second parameter set is set in advance and a predetermined condition regarding the water to be treated flowing into the rotary filter device is not satisfied, feedback control using the first parameter set is performed and the condition is satisfied. The present invention is characterized in that feedback control is performed using the second parameter set.

Further, a program for feedback control according to the present invention is a program for feedback control of a rotary filter device provided with an endless strip filter movable by rotation of a rotor, and includes a parameter set for feedback control. A determination function that determines whether a predetermined condition regarding the water to be treated flowing into the rotary filter device is satisfied when the first parameter set and the second parameter set are set in advance and executed by a computer. a first control function that performs feedback control using the first parameter set when the determination function determines that the condition is not satisfied; and a first control function that performs feedback control using the first parameter set when the determination function determines that the condition is satisfied. A second control function of performing feedback control using the second parameter set is realized when the second parameter set is used.

Further, the filter system according to the present invention is a filter system including a rotary filter device provided with an endless band-shaped filter movable by rotation of a rotor, and a control device that performs feedback control of the rotary filter device, A first parameter set and a second parameter set are set in advance in the control device as parameter sets for feedback control, and the control device is configured to control the control device so that a predetermined condition regarding the water to be treated flowing into the rotary filter device is satisfied. If the condition is not satisfied, feedback control using the first parameter set is performed, and when the condition is satisfied, feedback control using the second parameter set is performed.

According to these configurations, no matter which of the two parameter sets is used, feedback control is always performed, so the operating conditions of the device can be changed continuously. Therefore, even if it is necessary to shift to an operating condition with a different processing capacity, it is difficult to put a load on the device.

Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited to the preferred embodiments described below.

In one aspect of the feedback control method according to the present invention, it is preferable that the conditions are set based on the water level on the primary side of the endless strip filter.

According to this configuration, since the operating conditions can be changed as the water level rises, overflow on the primary side of the endless strip filter can be easily prevented.

In one aspect of the feedback control method according to the present invention, it is preferable that the conditions simultaneously satisfy the conditions expressed by the following equations (1) and (2).
L(t)>a (1)
L(t)-L(t-Δt)>b (2)
In the formula, L(t) is the water level on the primary side of the endless strip filter at a certain time t, Δt is a predetermined unit period, and a and b are predetermined threshold values.

According to this configuration, the cases where feedback control using the second parameter set is performed can be limited to cases where the necessity is particularly high.

In one aspect of the feedback control method according to the present invention, it is preferable that the second parameter set is a parameter set in which a proportional operation has a larger contribution than the first parameter set.

According to this configuration, feedback control can be performed using an appropriate parameter set depending on the degree of disturbance suppression required.

Further features and advantages of the invention will become clearer from the following description of exemplary and non-limiting embodiments, written with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a filter system according to an embodiment. FIG. 3 is a flow diagram showing the steps of a feedback control method according to the embodiment.

Embodiments of a feedback control method, program, and filter system according to the present invention will be described with reference to the drawings. An example in which the feedback control method according to the present invention is applied to control the rotary filter device 1 provided in the filter system 100 will be described below.

[Filter system configuration]
Filter system 100 includes a rotary filter device 1 and a control device 2 (FIG. 1).

The rotary filter device 1 is a rotary filter type residue separation device having a filter unit 11. The filter unit 11 is provided in the form of an endless strip-shaped filter in which a plurality of panel filters each having an opening of 0.1 to 1.0 mm are connected together, for example. Further, the rotary filter device 1 is provided with a plurality of rotors 12 for moving each panel filter of the filter unit 11. The rotor 12 is electrically connected to the control device 2, and transmits information regarding the operating state of the rotor 12 (rotation speed, current value, etc.) to the control device 2, and also sends control signals that determine the operating conditions of the rotor 12. It can be received from the control device 2.

In the rotary filter device 1, a filter unit 11 is provided so as to cross the flow path of the water to be treated W1 flowing into the rotary filter device 1. The filter unit 11 is provided in such a manner that it is inclined from the upstream side to the downstream side of the flow path of the water to be treated W1, and the panel filter moves from the bottom to the top on the primary side where the water to be treated W1 flows as the rotor 12 rotates. . The scum S contained in the water to be treated W1 is blocked by the filter unit 11, and the filtered water W2, which is water in the water to be treated W1, passes through the filter unit 11. The residue S remaining on the panel filter of the filter unit 11 is conveyed as the panel filter moves, and is peeled off from the filter unit 11 by the cleaning mechanism 13. The cleaning mechanism 13 includes, for example, a scraper 13a that scrapes off mustard residue S from the filter unit 11, and a sprayer 13b that sprays cleaning water from the back side of the filter unit 11 to peel off the mustard residue S from the filter unit 11. including.

A water level gauge 14 is provided on the primary side of the filter unit 11 of the rotary filter device 1, and the water level on the primary side of the filter unit 11 can be detected. The output of the water level gauge 14 is input to the control device 2.

The control device 2 is implemented as a known computer. Therefore, the control device 2 includes common components of a computer, such as an arithmetic unit, a storage device, and an input/output device. Note that a control program for performing feedback control of the rotary filter device 1 is installed in the control device 2, and the control program is an example of a program according to the present invention. The control device 2 is electrically connected to the rotor 12 and the water level gauge 14, and receives information regarding the operating state of the rotor 12 (rotation speed, current value, etc.) and the water level detected by the water level gauge 14. It is possible to transmit control signals that determine the operating conditions of the vehicle. Such a control signal is generated by feedback control described below.

[Feedback control method]
The feedback control method according to this embodiment is realized by executing a control program installed in the control device 2. In this embodiment, the feedback control is implemented as PI control, and two parameter sets for PI control are set in advance. The first parameter set is used for normal control, and the second parameter set is used for emergency control. An emergency situation refers to a time when the load on the rotary filter device 1 suddenly increases due to an external factor such as rain or cleaning of a pump station, and a normal time refers to a time that does not correspond to an emergency situation. The two parameter sets are stored in the storage device of the control device 2 and read as necessary.

Comparing both parameter sets, the second parameter set is set to have a more sensitive response to disturbance than the first parameter set. Specifically, the second parameter set is a parameter set in which the contribution of proportional operation is larger (the proportionality constant is larger) than in the first parameter set. Also, although the integration time is smaller for the second parameter set than for the first parameter set, when the second parameter set is applied it is faster than when the first parameter set is applied. Since the variables are relatively large, the product of the variables and the integration time will have the same value no matter which parameter set is applied. That is, the contribution of the integral operation is equal between the first parameter set and the second parameter set. If the second parameter set is adopted, the effect of suppressing disturbance will be greater, but if it is used regularly, there is a risk of overshoot occurring, and the equipment itself (especially the rotor ) There is a concern that the load on Therefore, in this embodiment, the second parameter set is employed only when there is a strong demand for disturbance suppression, that is, in an emergency, and the first parameter set is employed at other times (normal times).

The determination between normal times and emergency times is made based on the output of the water level gauge 14 (the water level on the primary side of the filter unit 11). Specifically, when each condition expressed by the following equations (1) and (2) is simultaneously satisfied, it is determined that the situation is an emergency.
L(t)>a (1)
L(t)-L(t-Δt)>b (2)
In the formula, L(t) is the water level on the primary side of the filter unit 11 at a certain time t, Δt is a predetermined unit period, and a and b are predetermined threshold values.

Specifically, the determination is made according to the procedure shown in the flowchart 200 of FIG. The first determination is determination 201 based on equation (1), and is a determination related to the current state of the water level on the primary side of the filter unit 11. When the water level L(t) at a certain time t is below the predetermined threshold value a (determination 201: No), it can be said that there is sufficient capacity on the primary side of the filter unit 11 to receive the water to be treated W1. . In this case, even if the amount of inflow of the water to be treated W1 increases due to a disturbance, it is possible to continue receiving the water to be treated W1, so there is no need to shift to emergency control. Therefore, if the condition of formula (1) is not satisfied, it is determined that the situation is normal without performing the determination of formula (2) (process 205), and feedback control using the first parameter set is continued (process 206). On the other hand, if the condition of formula (1) is satisfied (determination 201: yes), then the determination of formula (2) is performed.

The second determination is determination 202 based on equation (2), and is a determination related to the rising speed of the water level. When the amount of increase in water level L(t)-L(t-Δt) in the unit period Δt immediately before a certain time t is less than or equal to the predetermined threshold b (determination 202: No), the balance of the water to be treated W1 is approximately It can be said that they are in a state of balance. In this case, even if the water level is higher than the threshold a, there is little possibility that the water level will rise suddenly, so there is no need to shift to emergency control. Therefore, even if the condition of formula (1) is satisfied, if the condition of formula (2) is not satisfied, it is determined that the situation is normal (process 205), and feedback control using the first parameter set is performed. continues (process 206).

On the other hand, if the condition of formula (2) is satisfied (determination 202: yes), formula (1) and formula (2) are simultaneously satisfied, the water level is relatively high, and the inflow amount of water to be treated W1 is is larger than the treatment amount (the balance of the water to be treated W1 is not balanced). In this case, it is determined that it is an emergency (process 203). At this time, since it is necessary to temporarily increase the throughput of the rotary filter device 1 to prevent overflow of the water to be treated W1, feedback control using the second parameter set is performed (process 204). As mentioned above, the second parameter set has a more sensitive response to external disturbances than the first parameter set, so the output of the rotor 12 is increased in response to a sudden rise in the water level, and the rotary filter device 1 can be increased smoothly and quickly.

Thereafter, the determination based on the same flow is repeated to appropriately select a parameter set for use in feedback control according to the situation at the time the determination is made.

The threshold value a is determined in consideration of conditions such as the capacity of the rotary filter device 1, the normal inflow amount of the water to be treated W1 at the installation location of the rotary filter device 1, the rated capacity of the rotor 12, and the processing capacity of the control device 2. Can be set. As an example, the threshold a may be 60-70% of the full water level on the primary side of the filter unit 11.

The threshold value b and the unit period Δt may be set in consideration of the capacity of the water level gauge 14. For example, in the second determination (determination 202), if you want to determine that it is an emergency when the rising speed of the water level exceeds 0.5 cm per second, the combination of the threshold value b and the unit period Δt is b = 0.5Δt. Since it is not limited as long as it exists, there are an infinite number of times, such as 1 cm and 2 seconds, 2 cm and 4 seconds, 3 cm and 6 seconds, etc. Here, it can be said that it is preferable to adopt a combination with a short unit period Δt since it is less likely to delay the determination in an emergency. On the other hand, if the threshold value b is too small, the amount of increase in water level L(t)-L(t-Δt) compared with the threshold value b will be less than the minimum unit of water level difference that the water level meter 14 can detect. Therefore, the reliability of the value of the detected water level increase amount L(t)−L(t−Δt) is impaired, and the accuracy of the second determination (determination 202) is decreased. Therefore, among the combinations of the threshold b and the unit period Δt that give the rising speed of the water level when determining an emergency, the threshold b is an appropriate value in view of the accuracy of the water level gauge 14. The combination can be determined as follows.

For example, the unit period Δt may be a cycle for determining whether the situation is normal or an emergency. In this case, the amount of increase in water level L(t)-L(t-Δt) is the water level L(t) at the time of determination in a certain cycle and the water level L(t-Δt) at the time of determination one cycle before the relevant cycle. It can be identified as the difference between In other words, the water level is repeatedly recorded at a cycle of unit period Δt, and when the difference between the latest water level and the water level one cycle before that exceeds the threshold value b, it can be determined that the condition of equation (2) is satisfied. .

[Other embodiments]
Finally, other embodiments of the feedback control method, program, and filter system according to the present invention will be described. Note that the configurations disclosed in each of the embodiments below can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs.

In the above embodiment, an example was described in which the predetermined conditions for determining the parameter set used for feedback control are expressed by Equation (1) and Equation (2). However, in the feedback control method according to the present invention, the predetermined conditions for determining the parameter set used for feedback control are not limited. That is, the conditions may be based on the water level as in the above embodiment, or the conditions may be based on other physical properties of the water to be treated (such as flow rate, amount of suspended solids (SS), turbidity, etc.). .

In the above embodiment, the second parameter set is a parameter set in which the contribution of the proportional operation is larger than that of the first parameter set. However, the present invention is not limited to such an embodiment. In the feedback control method according to the present invention, the relationship between the first parameter set and the second parameter set is determined according to the purpose of setting the predetermined conditions set for determining the parameter set used for feedback control. , any relationship is sufficient as long as it can realize control suitable for each of the two states classified by the predetermined conditions.

In the above embodiment, the configuration in which feedback control is implemented as PI control has been described as an example. However, the feedback control according to the present invention is not limited to PI control, and may be, for example, PID control.

Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects, and the scope of the present invention is not limited thereby. Those skilled in the art will easily understand that modifications can be made as appropriate without departing from the spirit of the present invention. Therefore, other embodiments that are modified without departing from the spirit of the present invention are naturally included within the scope of the present invention.

INDUSTRIAL APPLICATION This invention can be utilized for sludge separation in an activated sludge treatment facility, for example.

100: Filter system 1: Rotary filter device 11: Filter unit 12: Rotor 13: Cleaning mechanism 13a: Scraper 13b: Spray 14: Water level gauge 2: Control device S: Scum W1: Water to be treated W2: Filtered water

Claims (6)

A method of feedback control of a rotary filter device provided with an endless strip filter movable by rotation of a rotor, the method comprising:
At least a first parameter set and a second parameter set are set in advance as parameter sets for feedback control,
performing feedback control using the first parameter set when a predetermined condition regarding the water to be treated flowing into the rotary filter device is not satisfied;
A feedback control method that performs feedback control using the second parameter set when the condition is satisfied. The feedback control method according to claim 1, wherein the condition is set based on a water level on the primary side of the endless strip filter. 3. The feedback control method according to claim 2, wherein the condition is that each condition expressed by the following equation (1) and equation (2) is simultaneously satisfied.
L(t)>a (1)
L(t)-L(t-Δt)>b (2)
In the formula, L(t) is the water level on the primary side of the endless strip filter at a certain time t, Δt is a predetermined unit period, and a and b are predetermined threshold values. 4. The feedback control method according to claim 1, wherein the second parameter set is a parameter set in which a proportional action has a larger contribution than the first parameter set. A program for feedback control of a rotary filter device provided with an endless strip filter movable by rotation of a rotor,
A first parameter set and a second parameter set are set in advance as feedback control parameter sets,
when executed by a computer,
a determination function that determines whether a predetermined condition regarding the water to be treated flowing into the rotary filter device is satisfied;
a first control function that performs feedback control using the first parameter set when the determination function determines that the condition is not satisfied;
a second control function that performs feedback control using the second parameter set when the determination function determines that the condition is satisfied; A filter system comprising a rotary filter device provided with an endless band-shaped filter movable by rotation of a rotor, and a control device that performs feedback control of the rotary filter device,
A first parameter set and a second parameter set are preset in the control device as parameter sets for feedback control,
The control device,
performing feedback control using the first parameter set when a predetermined condition regarding the water to be treated flowing into the rotary filter device is not satisfied;
A filter system configured to perform feedback control using the second parameter set when the condition is met.

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