Control table creation method, control table creation program, and water quality control method

Abstract

To provide a water quality control method capable of performing control for maintaining a water quality management item at a proper value at a low cost, and to provide a method and a program for creating a control table used for the method.SOLUTION: The control table creation method and the control table creation program create a control table by using actually measured data in a management system in actual operation. Further, the insufficient portion is calculated by an operation based on actually measured data. Therefore, the control table can be created without using an expensive device. In addition, the acquisition of data necessary for creating the control table can be handled by existing equipment, and the introduction cost can be kept low. In addition, this water quality control method does not cause a large calculation load on the management value setting device. Therefore, existing equipment can be used for the control value setting device, and the introduction cost of the present invention can be kept low.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a technology for controlling the amount of chemicals to be added so that a predetermined water quality control item at a downstream target point reaches a preset value, and in particular to a control table for setting the value of a water quality control item on the upstream side. Made by The present invention relates to a method for creating a control table, a program for creating a control table, and a water quality control method using the control table. [Background technology]

[0002] For example, Japan's water supply system is an important social infrastructure indispensable for social life and economic activity, providing a stable supply of safe, drinkable water via a distribution pipe network. The Water Supply Act Enforcement Regulations stipulate that chlorine disinfection requires that the free residual chlorine concentration (hereafter referred to as the residual salt concentration) of water at taps be maintained at 0.1 mg / L or higher. However, as Japan's population declines, the residence time in the distribution pipe network is on the rise, which in turn reduces the residual salt concentration during the water distribution process (management system), raising concerns about a decline in the disinfection effect during distribution. To address this issue, one possible solution is to increase the amount of disinfectant (typically sodium hypochlorite) added at the water purification facility where the water is delivered, thereby increasing the chlorine concentration at the time of supply.

[0003] However, a report by the "Tasty Water Research Group" of the Ministry of Health, Labor and Welfare in 1985 indicated that a residual salt concentration of 0.4 mg / L or less is required for tasty water. Furthermore, the "comfortable water quality" item, which supplements the water quality standards that came into effect in December 1993, specifies a residual salt concentration control setting of approximately 1 mg / L or less. Thus, with regard to tap water, the residual salt concentration must be properly managed based on a lower limit as a sanitary measure and an upper limit as a comfortable water quality item, and there are limits to managing the residual salt concentration throughout the entire water distribution network by adding chlorine only at the source.

[0004] One known solution to this problem is "additional chlorination," in which additional disinfectant is added at chemical injection points P, installed at distribution facilities such as distribution reservoirs along the water supply system, as shown in the schematic diagram in Figure 1. While multipoint injection is common for this method, given the recent decline in the number of waterworks employees, this method places a heavy burden on personnel and poses significant equipment costs due to the need for multiple chemical injection facilities. Therefore, there is a need to minimize the number of chemical injection points P for additional chlorination and achieve efficient addition. However, because flow rates and residence times vary depending on the pipe diameter, gradient, and water demand in a water supply system, simply determining a midpoint on a map (considering only the pipe length) is not necessarily the best chemical injection point P. To address this issue, the present inventors developed the following invention (Patent Document 1) regarding a chemical injection point selection method for selecting a chemical injection point P for efficient addition of chlorination. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6737920 Summary of the Invention [Problem to be solved by the invention]

[0006] The invention described in Patent Document 1 makes it possible to select an effective chemical injection point P midway through the management system, enabling efficient chlorination throughout the entire management system. Meanwhile, for example, the rate at which chlorine-based disinfectants injected into tap water decrease varies depending on the water temperature. In summer, when the water temperature is high, the decrease is rapid, resulting in a low residual salt concentration, while in winter, when the water temperature is low, the decrease is slow, resulting in a high residual salt concentration. Therefore, in order to maintain the residual salt concentration in the management system at an appropriate value, it is necessary to change the amount of chemical injected at the chemical injection point P according to the water temperature. Traditionally, such adjustments of the chemical injection amount in response to changes in water temperature have been made by managers based on experience. However, due to labor shortages, work efficiency, and workload reduction, there is a demand for automated control of these processes.

[0007] The most common control method for such a mechanism is feedback control, which adjusts the amount of chemicals added according to the measured value of a water quality control item (residual salt concentration) at target point E. However, in a water distribution network, the time (delay time) for water to travel from chemical addition point P to target point E is long, and in some cases it can take more than two days. With feedback control on a route with such a long delay time, there is a large amount of overshoot and undershoot, and the amount of chemicals added is repeatedly over or underdone, making it difficult to maintain an appropriate residual salt concentration.

[0008] Another possible method is to obtain measurement data, derive a regression equation, and then use this regression equation to calculate the amount of chemical to be added. However, experimental amounts (too much or too little) of chemicals cannot be added in an actual distribution pipe network that is in operation. As a result, the measurement data obtained tend to be concentrated around the appropriate value, making it difficult to derive an accurate regression equation and resulting in poor accuracy.

[0009] Furthermore, although learning and control using AI (artificial intelligence), which has been rapidly developing in recent years, is considered to be an effective method for such control systems, there is a problem in that the cost of creating AI equipment and AI programs is high, making it difficult to introduce from a cost perspective.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a water quality control method that can maintain water quality control items at appropriate values ​​at low cost using as many existing facilities as possible. Also, the control table used in this water quality control method can be created at low cost using as many existing facilities as possible. Made by The present invention aims to provide a method for creating a control table and a program for creating a control table. [Means for solving the problem]

[0011] The present invention provides (1) A control table creation method for creating a control table for controlling the amount of medicine injected at a medicine injection point P of a management system, The existing equipment installed in the management system monitors the water quality control items at the chemical injection point P and the downstream target point E, and based on the changes in the water quality control items,From the drug injection point P Rame Step S102: setting the arrival time to the target point E as a delay time τ; The existing equipment installed in the management system is Step S104 of acquiring water quality information of the management system for a predetermined period of time; Step S106: acquiring the value of the water quality control item at the chemical supply point P as a front end value Cu for a predetermined period of time; The value of the water quality control item at the target point E is the end value C L Step S10: 8 and, and The computer on which the control table creation program is running is Step S207: Calculating an average water quality value T of water quality information for a predetermined data period; Each front end value Cu and the rear end value C after the delay time τ has elapsed since the measurement of the front end value Cu Lτ and the front end value Cu or the rear end value C Lτ and the associated average water quality value T as group data in step S208; Step S220: creating a data table having rows and columns of equally spaced water quality value bands corresponding to the average water quality value T and equally spaced front end value bands corresponding to the front end values ​​Cu, and setting a center value Cn for each front end value band; In the data table, the rear end value C is entered in the cell where the water quality value band to which the average water quality value T of the group data belongs and the front end value band to which the front end value Cu belongs intersect. Lτ Step S222 of storing If there is a blank cell in the data table, all the rear end values ​​C of the water quality range in which the blank cell exists Lτ The decrease rate coefficient k of each trailing edge value C Lτ Step S302: calculating the center value Cn of the front end value band to which the value belongs based on the following formula A: k=(1 / τ)log e (Cn / C Lτ )···(A) The average value of the decrease rate coefficient k for each water quality range ave Step S304 of calculating The trailing value C of the blank cell Lτa rear end value calculation step S306 in which the rear end value is calculated by the following formula B using the center value Cn' of the front end value band to which the blank cell belongs; C Lτ =Cn'·exp(-k ave τ) (B) Multiple trailing edge values ​​C in one cell Lτ is stored, the stored trailing edge value C Lτ The average of the cell's trailing edge value C Lτ Step S332: a base table setting step S340 in which the data table is used as a base data table; Do The above-mentioned problem is solved by providing a control table creation method characterized by the above. (2) The control target value Ca of the water quality control item at target point E Setting for the computer Step S203, The computer After the basic table setting step S340, The rear end value C of the maximum leading end band of the basic data table Lτ does not reach the lower limit of the predetermined numerical range of the target control value Ca, step S346a of extending the upper limit front end value band of the data table in the direction of larger values ​​to provide an extended front end value band; The lowest leading edge value of the base data table, C Lτ exceeds the upper limit of the predetermined numerical range of the control target value Ca, step S346b of extending the lower limit front end value band of the data table in the direction of smaller values ​​to provide an extended front end value band; The rear end value C of the cell of the expanded front end value band Lτ based on the trailing edge value calculation step; Do The above problem is solved by providing the control table creation method described in (1) above. (3) A control table creation program for creating a control table for controlling the amount of medicine input at a medicine input point P of the management system, The water quality information data of the management system acquired in advance over a predetermined period, the data of the front end value Cu as the value of the water quality management item at the chemical injection point P, and the data of the rear end value C as the value of the water quality management item at the target point E L (Step S204) A process of acquiring a data period for calculating an average water quality value T, which is an average value of the water quality information (step S206); A process of calculating an average water quality value T of the water quality information using the data period (step S207); Each front end value Cu and the rear end value C after a preset delay time τ has elapsed since the measurement of the front end value Cu Lτ and the front end value Cu or the rear end value C Lτ and the associated average water quality value T, and grouping them into data (step S208); A process of creating a data table having rows and columns of equally spaced water quality value bands corresponding to the average water quality value T and equally spaced front end value bands corresponding to the front end values ​​Cu, and setting a center value Cn for each front end value band (step S220); In the data table, the rear end value C is entered in the cell where the water quality value band to which the average water quality value T of the group data belongs and the front end value band to which the front end value Cu belongs intersect. Lτ A process of storing (step S222) If there is a blank cell in the data table, all the rear end values ​​C of the water quality range in which the blank cell exists Lτ The decrease rate coefficient k of each trailing edge value C Lτ a process of calculating the center value Cn of the front end value band to which the value belongs based on the following formula A (step S302); k=(1 / τ)log e (Cn / C Lτ )···(A) The average value of the decrease rate coefficient k for each water quality range ave (step S304), The trailing value C of the blank cell Lτ a rear end value calculation process (step S306) in which the rear end value is calculated by the following formula B using the center value Cn' of the front end value band to which the blank cell belongs; C Lτ=Cn'·exp(-k ave τ) (B) Multiple trailing edge values ​​C in one cell Lτ is stored, the stored trailing edge value C Lτ The average of the cell's trailing edge value C Lτ (step S332), The above-mentioned problem is solved by providing a control table creating program that causes a computer to execute a basic table setting process (step S340) that uses the data table as a basic data table. (4) A process of setting a control target value Ca of the water quality control item at the target point E (step S203); After the basic table setting process (step S340), The rear end value C of the maximum leading end band of the basic data table Lτ If the upper limit of the predetermined numerical range of the target control value Ca is not reached, the upper limit of the front end value band of the data table is expanded in the direction of larger values ​​to provide an expanded front end value band (step S346a); The lowest leading edge value of the base data table, C Lτ exceeds the upper limit of the predetermined numerical range of the target control value Ca, a process of extending the lower limit front end value band of the data table in the direction of smaller values ​​to provide an extended front end value band (step S346b); The rear end value C of the cell of the expanded front end value band Lτ The above problem is solved by providing the control table creating program according to (3) above, which causes a computer to execute a process of calculating the trailing edge value (step S348). (5) A water quality control method for controlling the value of a water quality control item at a target point E using a control table created by the control table creation method described in (1) or (2), A setting step for determining the set values ​​of the water quality control items at the chemical injection point P; and a control step of controlling the amount of chemicals added so that the value of the water quality control item at the chemical addition point P becomes the set value, The setting step includes: Step S390 of setting a management target value for a water quality management item at the target point E; The rear end value C of the control table that is closest to the management target value Lτ Step S392: extracting the stored cells for each water quality value range, and creating a set value table using the center value Cn of the front end value range of the cell as the set value for each water quality value range; Step S401: Acquire the value of water quality information of the management system and calculate the average water quality value T' during control; Step S402: referring to the set value table, selecting a set value corresponding to the water quality value range to which the average water quality value T' belongs, and setting the selected set value as the set value for the control step; The above-mentioned problems are solved by providing a water quality control method characterized by having the following. (6) A control value setting device 50 is provided to perform the setting step, The above problem is solved by providing the water quality control method described in (5) above, wherein the control value setting device 50 has a recording unit 52 in which at least a control table is recorded, and a control unit 54 that creates a set value table and determines the set value of the control step based on the average water quality value T'. (7) A water quality control unit 30 is provided to perform the control step. The above problem is solved by providing the water quality control method described in (6) above, wherein the water quality control unit 30 has a control value measurement unit 32 that acquires the value of the control item at the chemical input point P, a chemical input unit 34 that inputs chemicals to the chemical input point P, and a control unit 36 ​​that controls the operation of the chemical input unit 34 so that the value of the water quality control item acquired from the control value measurement unit 32 becomes the set value determined by the control value setting device 50. [Effects of the Invention]

[0012] Control table according to the present invention Made byThe creation method and control table creation program create a control table using actual measurement data from a management system that is actually in operation. In addition, missing parts are calculated by calculations based on the actual measurement data. This makes it possible to create a control table without using expensive equipment such as AI devices. In addition, the data required to create the control table can be obtained using existing equipment, which helps keep implementation costs low. Furthermore, the water quality control method according to the present invention operates by storing a created control table in the control value setting device, and does not impose a large computational load on the control value setting device. This makes it possible to use existing equipment as the control value setting device, thereby keeping the introduction cost of the present invention low. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing an example of a water supply system as a management system to which the present invention is applied. [Figure 2] 1 is a process flowchart of a control table creation method and a water quality control method according to the present invention. [Figure 3] 4 is a flowchart of a control table creation program according to the present invention. [Figure 4] FIG. 10 is a diagram showing an example of a data table according to the present invention. [Figure 5] FIG. 10 is a diagram showing an example of a data table according to the present invention. [Figure 6] 1 is a diagram showing a control value setting device and a water quality control unit for carrying out the water quality control method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Control table according to the present invention Made byThe construction method, control table creation program, and water quality control method will be described with reference to the drawings. Here, the description will be given assuming that a water supply distribution pipe network is a management system, with a chemical dosing point P set along the network and a terminal facility of the management system as a target point E. The description will also assume that water quality information is the temperature of the water flowing through the management system and that the water quality control item is the residual salt concentration. However, the present invention is not limited to this. Examples of management systems include water purification facilities and wastewater treatment facilities, and examples of water quality information include residual salt concentration, turbidity, pH, flow rate, etc. Examples of water quality control items include turbidity and pH in addition to residual salt concentration. A more specific example would be controlling the amount or rate of coagulant dosing using a water purification facility as the management system, with the turbidity of raw water as the water quality information and the turbidity of purified water as the water quality control item. Another example would be controlling the amount or rate of additional chlorine-based disinfectant dosing using a water purification facility as the management system, with the residual salt concentration along the network as the water quality information and the residual salt concentration near the outlet as the water quality control item. Furthermore, the water quality information is not limited to one, but may be multiple, in which case the control table will be three-dimensional.

[0015] FIG. 1 is a schematic diagram showing an example of a water supply system as a management system to which the present invention is applied. This management system is connected to multiple distribution pipe networks (not shown), and tap water is distributed to each household through these distribution pipe networks. The water source S in FIG. 1 is, for example, a water distribution facility such as a water purification facility that supplies sterilized drinking water to the management system. If the management system is long and a water quality control parameter (here, residual salt concentration) falls below an appropriate value along the way, a chemical dosing point P is installed to perform chlorination. The chemical dosing point P may be, for example, a reservoir, a pressure reducing tank, a pumping station, or other well-known water distribution facility capable of chlorine injection. It is preferable to install the chemical dosing point P at a location where the chemical can be efficiently distributed using the invention described in Patent Document 1, etc. The present invention controls the amount or rate of chemical dosing at the chemical dosing point P, located upstream of the target point E, so that the value of the water quality control parameter (residual salt concentration) at the downstream target point E reaches the target value. It should be noted that the target point E is assumed to be the water distribution facility (terminal facility) located at the most downstream of the management system, but if there are multiple chemical supply points P, for example, the target point E may be a water distribution facility midway through the management system, and the present invention may be applied to the chemical supply point P immediately preceding that. Also, if there is no chemical supply point P between the water supply source S and the target point E, the water supply source S may be used as the chemical supply point P and the present invention may be applied.

[0016] Next, the control table according to the present invention Made by The method for creating the control system will be explained using the process flow chart in Figure 2(a). First, the time (delay time τ) from when the water flowing through the control system leaves the previous chemical injection point P until it reaches the target point E is acquired (step S102). This delay time τ is 、 The water quality control item (residual salt concentration) is monitored at the chemical injection point P and the target point E, and the time it takes for the change in the amount of chemical injected (water quality control item) at the chemical injection point P to be reflected in the value of the water quality control item at the target point E is obtained. 。 The delay time τ is basically a fixed value. The delay time τ is sufficient in units of hours, and does not need to be in units of minutes.

[0017] Next, water quality information for the management system is measured for a predetermined period and obtained. There are no particular limitations on the frequency of measuring water quality information at this time, but if the water quality information is water temperature, it is preferable to measure it at least twice a day when the air temperature (water temperature) is high and once at night when the air temperature (water temperature) is low, and basically it is preferable to measure it every hour. Note that the location at which water quality information is measured is not necessarily limited to the chemical injection point P or the target point E, and it can be measured at any location within the management system or at any water distribution facility. In addition, information on the measurement date and time, which will be necessary for later group data compilation, is recorded in the water quality information (step S104).

[0018] Also, before and after this, the water quality control item (residual salt concentration) at the chemical injection point P is measured, and this is set as the front end value Cu (step S106). The measurement point of the front end value Cu is preferably near the outflow point of the chemical injection point P where the chemical is sufficiently dissolved. Also, the water quality control item (residual salt concentration) at the target point E is measured, and this is set as the rear end value C L (Step S108). L There is no particular limitation on the measurement frequency of the Lτ It is particularly preferable that both values ​​are set to one hour so that the leading end value Cu and the trailing end value C L The information on the measurement date and time, which will be required for group data creation later, is recorded in the data.

[0019] And these water quality information, front end value Cu, rear end value C L The acquisition of data is continued for a predetermined period. In particular, when the water quality information is water temperature, data is acquired for high temperatures in summer and low temperatures in winter, so the acquisition is continued for at least six months, including summer and winter, and preferably for one year. This completes the acquisition of data necessary for deriving the control table.

[0020] Next, these water quality information, the front end value Cu, the rear end value C L A control table is created from the values ​​of (step S200) as follows: Figure 3 is a flowchart of a control table creation program according to the present invention.

[0021] First, the delay time τ acquired in step S102 is input into a computer running the control table creation program according to the present invention (step S202), and then the control target value Ca of the water quality control item (residual salt concentration) at the target point E is input into the computer (step S203). Next, the water quality information (water temperature), the front end value Cu, and the rear end value C acquired in steps S104, S106, and S108 are input into the computer. L The data is read (step S204).

[0022] Next, the control table creation program acquires a data period for calculating the average water quality value T of the water quality information (step S206). Here, if the water quality information is water temperature, the data period is preferably a multiple of 24 hours so that the average of the measurement data during the daytime when the temperature is high and the measurement data during the nighttime when the temperature is low can be obtained. In addition, the 24-hour multiple a is preferably set by calculating using the following formula C based on the delay time τ. a=[0.5×(1+(τ / 12))] (C) Here, [ ] means the Gaussian symbol (floor function). Therefore, if the delay time τ is 28 hours, a=[0.5×(1+2.33)] a=[1.667] a=1, and the data period is a×24=24 hours. Also, if the delay time τ is 37 hours, a=[2.042] a=2, and the data period is a×24=48 hours. The data period may be calculated by the control table creation program itself, or may be calculated by a person or another computer and input into the control table creation program.

[0023] Next, the control table creation program calculates the average value of the water quality information for the data period set in step S206, and sets it as the average water quality value T. The starting point of the data period at this time is the leading end value Cu or the trailing end value C, which will be grouped later.Lτ This is related to the point that, for example, the front end value Cu may be measured, but it is most preferable to do it as follows: First, the front end value Cu to be grouped is selected, and the rear end value C after the delay time τ from the measurement of this front end value Cu is measured. Lτ Then, extract this trailing edge value C Lτ The average water quality value T is calculated by taking the point going back the data period from the measurement time of the average water quality value T as the starting point of the data period. Lτ The average value of the water quality information for the data period ending at the measurement time of the preceding value Cu is set as the average water quality value T (step S207). Lτ , and this average water quality value T is grouped (step S208).

[0024] Next, the control table creation program creates a data table with rows and columns of evenly spaced water quality value bands and evenly spaced leading edge value bands (step S220). These water quality value bands and leading edge value bands are set to include the ranges of the average water quality value T and leading edge value Cu obtained through measurement. The numerical width of each water quality value band and leading edge value band may be fixed, or the ranges of the maximum and minimum values ​​of the average water quality value T and leading edge value Cu may be set by evenly dividing them into a predetermined number of bands, for example, 10 to 20 bands. For example, if the average water quality value T (water temperature) is in the range of 2°C to 23°C, the leading edge value Cu (residual salt concentration) is in the range of 0.38mg / L to 0.51mg / L, and the numerical width of the water quality value band is 1°C and the numerical width of the leading edge value band is 0.01mg / L, then if the center value of the water quality value band is Tn, then the numerical range of one water quality value band is Tn ±0.5°C, where Tn = 2, 3, ..., 23. If the center value of each leading edge value band is Cn, then the numerical range of one leading edge value band is Cn ±0.005mg / L, where Cn = 0.38, 0.39, ..., 0.51. That is, in this case, as shown in Figure 4(a), the data table is set such that the center value Tn of the water quality value range (Tn±0.5°C) is set in the range of 2°C to 23°C in increments of 1°C, and the center value Cn of the upper limit value range (Cn±0.005 mg / L) is set in the range of 0.38 mg / L to 0.51 mg / L in increments of 0.01 mg / L.

[0025] Next, for each group data created in step S208, the control table creation program stores the rear end value C of the group data in the cell where the water quality value band to which the average water quality value T belongs and the front end value band to which the front end value Cu belongs intersect. Lτ For example, if the average water quality value T is 14.3°C, the leading end value Cu is 0.482mg / L, and the trailing end value C Lτ In the case of the group data where the water quality value range of 14±0.5°C intersects with the front value range of 0.48±0.005mg / L, the rear value C Lτ The value 0.215 mg / L is stored. Then, this process is performed for all group data (step S222).

[0026] It is assumed that the management system to which the present invention is applied is already in actual operation. In this case, the end value C Lτ The upper limit value Cu cannot deviate significantly from the control target value (for example, 0.2 mg / L). Also, the upper limit value Cu cannot deviate significantly from the specified range. For this reason, the lower limit value C Lτ In this area, multiple trailing edge values ​​C are stored in one cell. Lτ will be stored.

[0027] In addition, the administrator increases the dosage of disinfectant in the summer when water temperatures are high and the rate of chlorine disinfectant depletion is rapid, and decreases the dosage in the winter when water temperatures are low and the rate of depletion is slower, thereby maintaining water quality control items at target point E near the management target values. For this reason, as shown in Figure 4(b), in the lower water quality value range, cells in the front value range with small numerical values ​​(low disinfectant dosage) tend to fill relatively easily, while cells in the front value range with large numerical values ​​(high disinfectant dosage) tend to have few corresponding group data and many blank cells. Conversely, in the higher water quality value range, cells in the front value range with large numerical values ​​(high disinfectant dosage) tend to fill relatively easily, while cells in the front value range with small numerical values ​​(low disinfectant dosage) tend to have few corresponding group data and many blank cells. Thus, there is a bias in the group data obtained, and it is highly likely that blank cells will occur in some areas.

[0028] Therefore, when there is a blank cell in the data table (step S300: Yes), the control table creation program according to the present invention creates a control table of all the rear end values ​​C belonging to the water quality value range in which the blank cell exists. Lτ The decrease rate coefficient k is calculated based on the following formula A (step S302). Note that Cn in the following formula A is the end value C Lτ is the center value Cn of the front end value band to which k=(1 / τ)log e (Cn / C Lτ )···(A)

[0029] Next, the control table creation program calculates the average value k of the calculated reduction rate coefficient k. ave is calculated for each water quality range (step S304).

[0030] Next, the control table creation program calculates the trailing value C of the blank cell using the following formula B. Lτ (rear end value calculation step S306). Note that Cn' in the following formula B is the center value Cn of the front end value range of the blank cell. C Lτ =Cn'·exp(-k ave τ) (B) The control table creation program then repeats these processes until there are no more blank cells.

[0031] Then, all cells in the data table are assigned the trailing value C Lτ is stored and there are no blank cells (step S300: No), the control table creation program stores multiple trailing edge values ​​C Lτ Check whether there is a cell that stores multiple trailing edge values ​​C Lτ is stored (step S330: Yes), the trailing edge value C stored in that cell Lτ The average of the cell's trailing edge value C Lτ (Step S332). Then, these processes are performed for a plurality of trailing edge values ​​C Lτ Repeat until there are no more cells containing

[0032] As a result, as shown in Figure 4(c), the trailing edge value C Lτ are stored one by one (step S330: No). Then, the control table creation program uses this data table as the basic data table (basic table setting step S340). L ) is maintained at a value roughly close to the control target value Ca throughout the year, the basic data table shows that the end value C is close to the control target value Ca in all water quality ranges. Lτ Therefore, in this case, this basic data table becomes the control table. However, depending on the acquired data, the trailing edge value C Lτ There may be a range of water quality values ​​where the Ca falls outside the management target value.

[0033] Therefore, the control table creation program then calculates the rear end value C stored in the cell of the maximum front end value range. Lτ Check these trailing edge values ​​C Lτ If any one of the values ​​does not reach the lower limit of the predetermined range of the target control value Ca (step S344a: Yes), the upper limit front end value band is expanded in the direction of larger values ​​to set an expanded front end value band Wb (step S346a), as shown in Fig. 5. Then, the process proceeds to step S348.

[0034] For example, if the control target value Ca is 0.2 mg / L and the numerical range is ±0.005 mg / L, the lower limit of the numerical range of the control target value Ca is 0.195 mg / L. The largest front-end value range in the basic data table of FIG. 4(c) is the column with a center value Cn of 0.51 mg / L, and the rear-end value C Lτ If any one of the values ​​does not reach the lower limit of the control target value Ca, an extended front end value band Wb is set as shown in FIG. 5. In FIG. 5, the maximum rear end value C of the front end value band is set Lτ Since all values ​​exceed the lower limit of 0.195 mg / L of the numerical range of the control target value Ca, there is no need to set the pre-extension limit band Wb. However, for the sake of convenience, Figure 5 shows an example in which the pre-extension limit band Wb is set.

[0035] Also, the rear end value C of the maximum front end value range Lτ If all of the lower limit values ​​of the numerical range of the control target value Ca are exceeded (step S344a: No), the control table creation program then calculates the rear end value C stored in the cell of the smallest front end value range in the basic data table. Lτ Check these trailing edge values ​​C Lτ If any one of the values ​​exceeds the upper limit of the predetermined numerical range of the control target value Ca (step S344b: Yes), the lower limit of the front end value band of the basic data table is extended in the direction of smaller values ​​to set an extended front end value band Ws (step S346b), as shown in FIG. 5. Then, the process proceeds to step S348. Here, the smallest front end value band in FIG. 4(c) is the column with a center value Cn of 0.38 mg / L, and the upper limit of the numerical range of the control target value Ca is 0.205 mg / L. Then, the rear end value C of the 0.38 mg / L column is Lτ When checking, the center value Tn is the rear end value C of the water quality range of 2℃ to 8℃. Lτ is 0.207 mg / L or more, exceeding the upper limit of 0.205 mg / L. Therefore, the control table creation program expands the lower limit front end value band to set the expanded front end value band Ws. Note that at the time of installation, all cells for the expanded front end value bands Wb and Ws are left blank.

[0036] Next, in step S348, the control table creation program calculates the average value k of the decrease speed coefficient k calculated in step S304 in the same manner as in the rear end value calculation step S306. ave The rear value C of the blank cells of the extended front value band Wb, Ws is Lτ Then, the process proceeds to step S344a and these processes are repeated.

[0037] For example, in Figure 5, the center value Tn is the end value C of all the water quality values ​​in the range of 2°C to 8°C. Lτ The downward extension of the front end band Ws is repeated until the center value Cn falls below the upper limit of 0.205 mg / L, and finally the smallest front end band is the extended front end band Ws with a center value Cn of 0.30 mg / L. In this way, the rear end value Cn that falls within the numerical range of the control target value Ca in all water quality bands is LτThe expansion front end bands Wb and Ws are expanded until the average value k of the reduction rate coefficient k is obtained. ave The trailing edge value C Lτ Then, the rear end value C near the control target value Ca is calculated. Lτ (The bold trailing edge value C in Figure 5) Lτ ) are acquired for all water quality value ranges (step S344b: No), the control table creation program uses this as the final control table (step S334). Made by The creation of the control table by the creation method and the control table creation program is completed.

[0038] Next, a water quality control method according to the present invention using this control table will be described. As shown in Figure 2(b), the water quality control method according to the present invention includes a setting step of determining the setting values ​​of the water quality management items at the chemical supply point using the control table, and a control step of controlling the amount of chemical supplied at the chemical supply point based on the setting values ​​determined in the setting step.

[0039] 6 shows a control value setting device 50 and a water quality control unit 30 for carrying out the water quality control method of the present invention. First, the control value setting device 50 of the present invention has a recording unit 52 in which at least the control table created as described above is recorded, and a control unit 54 that determines the setting values ​​for the water quality control items.

[0040] The water quality control unit 30 also has a control value measurement unit 32 that acquires the value of the control item (here, residual salt concentration) at the chemical injection point P, a chemical injection unit 34 that injects a predetermined chemical into the chemical injection point P, and a control unit 36 ​​that controls the operation of the chemical injection unit 34. It is preferable that the chemical injection unit 34 be located upstream of the chemical injection point P, and the control value measurement unit 32 be installed downstream of the chemical injection point P, particularly near the outflow area.

[0041] In the water quality control method according to the present invention, first, the manager inputs the control target value Ca for the water quality control item (residual salt concentration) at the target point E into the control unit 54 of the control value setting device 50 (step S390). The control target value Ca input here is the same as the control target value Ca when the control table was created. Therefore, the control target value Ca here is set to a residual salt concentration of 0.2 mg / L.

[0042] The control unit 54 receives the input of the control target value Ca, refers to the control table recorded in the recording unit 52, and calculates the end value C that is closest to the control target value Ca in each water quality value range. Lτ The control table is provided with an extended front end value range Wb and an extended front end value range Ws as needed to fill in any missing areas, so the rear end value C of the extracted cell is basically Lτ will be within a predetermined numerical range close to the control target value Ca. Next, the front-end value range of the extracted cell is referenced, and its center value Cn is extracted and used as a set value table corresponding to each piece of water quality information (water temperature) (step S392). This set value table is a table showing the residual salt concentration (control item) at the chemical injection point P when, for a certain water temperature (water quality information), the residual salt concentration (control item) at the target point E after the delay time τ has elapsed is around the control target value Ca (residual salt concentration 0.2 mg / L).

[0043] It is preferable to use existing equipment or add functions to the water quality control unit 30 and control value setting device 50 whenever possible. In particular, if a general-purpose PLC (Programmable Logic Controller) is used for the control value setting device 50, the present invention can be introduced without incurring new equipment costs by inputting a program and control table that perform the above setting steps into the control value setting device 50 (general-purpose PLC).

[0044] Next, the water quality information acquisition means 10 acquires the value of water quality information (here, water temperature) of the management system and outputs it to the control unit 54 of the management value setting device 50 (step S400). Note that the water quality information acquisition means 10 does not necessarily have to be installed at the chemical injection point P, but may be installed at any location in the management system and acquire water quality information via communication or the like.

[0045] Next, the control unit 54 of the control value setting device 50 receives this water quality information, takes a moving average over a preset data period, and calculates an average water quality value T' during control (step S401). Note that this data period during control does not need to be the same as the data period when the control table was created, and it is preferable to set it to a relatively long period such as 3 days, 5 days, or 1 week to eliminate the effects of temporary changes in raw water temperature due to sudden high or low temperatures, heavy rain, etc.

[0046] Next, the control unit 54 of the control value setting device 50 refers to the set value table at preset time intervals and selects a set value R(n) that corresponds to the average water quality value T' at that time. The control value setting device 50 then outputs this set value R(n) to the water quality control unit 30 (step S402). The output interval for this set value R(n) is not particularly limited, and may be every 12 hours, one day, two days, or three days, but it is preferable to output it once a day.

[0047] Furthermore, for example, if the data period during control cannot be taken long, a low-pass filter can be inserted as shown in the following formula D to prevent sudden changes in the set value: where α is the filter coefficient (fixed value) and is generally a value of around 0.3, between 0.1 and 0.4. R'(n)=α·R'(n-1)+(1-α)R(n)···(D) With this configuration, even if the data period during control cannot be long, it is possible to prevent the set value R'(n) from changing significantly from the immediately preceding set value R'(n-1), thereby preventing temporary large changes in the set value R(n) due to sudden abnormalities such as erroneous measurement.The above corresponds to the setting step of the water quality control method according to the present invention.

[0048] Next, the control unit 36 ​​of the water quality control unit 30 receives the set value R(n) (or R'(n) if a low-pass filter is provided) from the control value setting device 50 and controls the chemical feed unit 34 to adjust the amount of chemical feed so that the value of the control item (residual salt concentration) acquired by the control value measurement unit 32 becomes the set value R(n) (step S404). Then, the water whose control item (residual salt concentration) has become the set value R(n) at the chemical feed point P flows through the control system and reaches the target point E with approximately a delay time τ. At this time, the residual salt concentration in the water decreases, but the residual salt concentration of the water leaving the chemical feed point P has been adjusted to the set value R(n) that takes this decrease into account. Therefore, the residual salt concentration of the water when it reaches the target point E will be close to 0.2 mg / L, which is the control target value Ca.

[0049] For example, if the average water quality value T of the water quality information (water temperature) increases, the control value setting device 50 selects a relatively high set value R(n) corresponding to this average water quality value T from the set value table and outputs it to the water quality control unit 30. In response to this relatively high set value R(n), the water quality control unit 30 increases the amount of chemical added at the chemical addition point P. The water that flows out from the chemical addition point P has a high water temperature, resulting in a large decrease in the residual salt concentration (a large amount of chemical added), but the residual salt concentration is accordingly high. Therefore, the residual salt concentration at the target point E is close to the control target value Ca of 0.2 mg / L. In addition, if the average water quality value T of the water quality information (water temperature) decreases, the control value setting device 50 selects a relatively low set value R(n) corresponding to this average water quality value T from the set value table and outputs it to the water quality control unit 30. In response to this relatively low set value R(n), the water quality control unit 30 decreases the amount of chemical added at the chemical addition point P. Furthermore, although the water that flows out from the chemical injection point P has a low water temperature, resulting in a small decrease in the residual salt concentration (a small amount of chemical injected), the residual salt concentration at the time of chemical injection is accordingly low, and therefore the residual salt concentration at the target point E is close to the control target value Ca of 0.2 mg / L.

[0050] If the control target value Ca changes due to a large change in water demand at the target point E, the administrator can select the rear end value C that is closest to the control target value Ca' in each water quality range in the control table. Lτ Extract these trailing edge values ​​C LτIt is then confirmed whether the extracted end value C is within the range of the preset control target value Ca'. Lτ If all of these values ​​are within the range of the control target value Ca', the administrator inputs the changed control target value Ca' to the control value setting device 50. As a result, the control value setting device 50 sets the rear end value C closest to the changed control target value Ca'. Lτ The cell storing the above is extracted for each water quality value range, and the center value Cn of the front end value range of that cell is extracted and used as the new setting value table. As a result, the control item at target point E is maintained at a value close to the new control target value Ca'.

[0051] In addition, the extracted trailing edge value C Lτ If even a part of the control target value Ca' falls outside the range, steps S344a to S334 are performed using the changed control target value Ca'. As a result, an extended front end value band Wb or an extended front end value band Ws is provided in the control table, and similarly, the rear end value C within the range of the control target value Ca' is set. Lτ is calculated.

[0052] The control table corrected in this way is recorded in the recording unit 52 of the control value setting device 50, and when the manager inputs a new control target value Ca', the control value setting device 50 extracts the setting value table corresponding to the changed control target value Ca' and outputs the setting value R(n). As a result, the control item at the target point E is maintained at a value close to the new control target value Ca'.

[0053] In addition, water quality information, front end value Cu, rear end value C L is often constantly monitored, so if, for example, an average water quality value T is obtained that exceeds the range of the water quality value range in the existing control table, this data can be taken into account to supplement the control table and sent to the management value setting device 50, thereby automatically updating the control table.

[0054] As described above, the control table according to the present invention Made byThe creation method and control table creation program create a control table using actual measurement data from a management system that is actually in operation. In addition, missing parts are calculated by calculations based on the actual measurement data. This makes it possible to acquire measurement data while the management system is in operation. Also, the control table can be created without using expensive equipment such as AI devices. Furthermore, the data required to create the control table is basically items that are generally monitored in the management system, so no new equipment is required to acquire the data. Therefore, it is possible to generally handle it using existing equipment, which helps keep implementation costs low.

[0055] Furthermore, in the water quality control method according to the present invention, an optimal value for the water quality control item (residual salt concentration) at the chemical injection point P is set based on a control table derived from actual measurement data in an actual management system as described above. Then, by the water quality control unit 30 controlling the amount of chemical injection so that the value of the water quality control item becomes the set value, the water quality control item (residual salt concentration) at a target point E far downstream from the chemical injection point P can be maintained near the appropriate control target value Ca.

[0056] The control table is basically calculated by another computer and then recorded in the control value setting device 50 for use. Furthermore, because the control value setting device 50 only references this control table as needed, no significant computational load is placed on the control value setting device 50. Therefore, the control value setting device 50 does not require expensive equipment capable of complex calculations, and can use equipment such as a general-purpose PLC, which has traditionally been used to control chemical dosage amounts. Furthermore, when a general-purpose PLC is used as the control value setting device 50, the water quality control method of the present invention can be implemented using only existing equipment by inputting the program for performing the setting steps and the control table into the control value setting device 50, without the need for additional equipment. Furthermore, even when a new control value setting device 50 is introduced, inexpensive equipment can be used. This allows the introduction cost of the present invention to be kept extremely low.

[0057] And the control table according to the present invention Made by According to the water quality control method, control table creation program, and water quality control method, the control value setting device 50 and water quality control unit 30 automatically adjust the values ​​of water quality control items (residual salt concentration) in response to changes in water quality information, which was previously done by an administrator based on experience. This reduces the administrator's burden and cuts labor costs. Furthermore, because the values ​​of water quality control items are adjusted based on a control table based on actual measurement data from an actual management system, more appropriate control can be achieved than with conventional adjustments made by an administrator. Furthermore, this adjustment operation can be performed periodically at preset intervals. This allows for continuous appropriate management throughout the year.

[0058] The control table shown in this example Made by The above-mentioned method for creating a control table, the control table creation program, and the water quality control method are merely examples, and the configuration and order of each step and process, the method for acquiring each piece of data, the device configuration, operation, etc. can be modified and implemented within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0059] 30 Water Quality Control Department 32 Control value measurement section 34 Drug injection section 36 Control Unit 50 Control value setting device 52 Recording section 54 Control Unit P Drug injection point E. Target point S306 Rear end value calculation step S340 Basic table setting step

Claims

1. A control table creation method for creating a control table for controlling the amount of medicine injected at a medicine injection point in a management system, comprising: A step of setting a delay time τ as the arrival time from the drug injection point to a downstream target point; acquiring water quality information of the management system for a predetermined period of time; A step of acquiring the value of the water quality control item at the chemical injection point as a front end value Cu for a predetermined period of time; The value of the water quality control item at the target point is the end value C Ｌ and acquiring the value for a predetermined period of time as Calculating an average water quality value T of water quality information for a predetermined data period; Each leading edge value Cu and the trailing edge value C after the delay time τ has elapsed since the leading edge value Cu was measured Ｌτ and the front end value Cu or the rear end value C Ｌτ and the associated average water quality value T, creating a data table having rows and columns of equally spaced water quality value bands corresponding to the average water quality value T and equally spaced leading edge value bands corresponding to the leading edge values ​​Cu, and setting a center value Cn for each leading edge value band; In the data table, the rear end value C is entered in a cell where the water quality value band to which the average water quality value T of the group data belongs and the front end value band to which the front end value Cu belongs intersect. Ｌτ and storing the If there is a blank cell in the data table, all the rear end values ​​C of the water quality range in which the blank cell exists Ｌτ The decrease rate coefficient k of each trailing edge value C Ｌτ a step of calculating the value of the front end value band Cn based on the following formula A using the center value Cn of the front end value band to which the value of the front end value band belongs; k = (1 / τ) log ｅ (Cn / C) Ｌτ )... (A) The average value of the decrease rate coefficient k for each water quality range ａｖｅ and calculating The trailing edge value C of the blank cell Ｌτ a rear end value calculation step of calculating the rear end value by the following formula B using the center value Cn′ of the front end value band to which the blank cell belongs; C Ｌτ =Cn'・exp(-k ａｖｅ ・τ)・・・・(B) Multiple trailing edge values ​​C in one cell Ｌτ is stored, the stored trailing edge value C Ｌτ The average of the cell's rear end value C Ｌτ and a base table setting step of setting the data table as a base data table.

2. setting a control target value Ca for a water quality control item at a target point; After the basic table setup step, The rear end value C of the maximum front end value band of the basic data table Ｌτ is less than the lower limit of the predetermined numerical range of the target control value Ca, the upper limit front end value band of the data table is expanded in the direction of larger values ​​to provide an expanded front end value band; The rear end value C of the minimum front end value band of the basic data table Ｌτ exceeds the upper limit of the predetermined numerical range of the target control value Ca, the lower limit front end value band of the data table is extended in the direction of smaller values ​​to provide an extended front end value band; The rear end value C of the cell of the expanded front end value band Ｌτ 2. The control table creating method according to claim 1, further comprising the step of calculating the trailing edge value based on the trailing edge value calculation step.

3. A control table creation program for creating a control table for controlling the amount of medicine input at a medicine input point in a management system, The water quality information data of the management system acquired in advance over a predetermined period, the data of the front end value Cu as the value of the water quality management item at the chemical injection point, and the data of the rear end value C as the value of the water quality management item at the target point Ｌ A process of reading the data of A process of acquiring a data period for calculating an average water quality value T, which is an average value of the water quality information; A process of calculating an average water quality value T of water quality information using the data period; Each leading edge value Cu and a trailing edge value C after a preset delay time τ has elapsed since the leading edge value Cu was measured Ｌτ and the front end value Cu or the rear end value C Ｌτ and the associated average water quality value T, and grouping the data; A process of creating a data table having rows and columns of equally spaced water quality value bands corresponding to the average water quality value T and equally spaced front end value bands corresponding to the front end values ​​Cu, and setting a center value Cn for each front end value band; In the data table, the rear end value C is entered in a cell where the water quality value band to which the average water quality value T of the group data belongs and the front end value band to which the front end value Cu belongs intersect. Ｌτ A process of storing If there is a blank cell in the data table, all the rear end values ​​C of the water quality range in which the blank cell exists Ｌτ The decrease rate coefficient k of each trailing edge value C Ｌτ A process of calculating the center value Cn of the front end value band to which the value belongs based on the following formula A: k = (1 / τ) log ｅ (Cn / C) Ｌτ )... (A) The average value of the decrease rate coefficient k for each water quality range ａｖｅ A process of calculating The trailing edge value C of the blank cell Ｌτ a rear end value calculation process in which the rear end value is calculated by the following formula B using the center value Cn′ of the front end value band to which the blank cell belongs; C Ｌτ =Cn'・exp(-k ａｖｅ ・τ)・・・・(B) Multiple trailing edge values ​​C in one cell Ｌτ is stored, the stored trailing edge value C Ｌτ The average of the cell's rear end value C Ｌτ and a control table creation program that causes a computer to execute a basic table setting process that sets the data table as a basic data table.

4. A process of setting a control target value Ca for a water quality control item at a target point; After the basic table setting process, The rear end value C of the maximum front end value band of the basic data table Ｌτ is less than the lower limit of the predetermined numerical range of the target control value Ca, a process of extending the upper limit front end value band of the data table in the direction of a larger numerical value to provide an extended front end value band; The rear end value C of the minimum front end value band of the basic data table Ｌτ exceeds the upper limit of the predetermined numerical range of the target control value Ca, a process of extending the lower limit front end value band of the data table in the direction of smaller values ​​to provide an extended front end value band; The rear end value C of the cell of the expanded front end value band Ｌτ 4. The control table creating program according to claim 3, further comprising: a step of calculating the trailing edge value based on the trailing edge value calculation step.

5. 3. A water quality control method for controlling values ​​of water quality control items at a target point using a control table created by the control table creation method according to claim 1 or 2, comprising: A setting step for determining the set values ​​of the water quality control items at the chemical injection point; a control step of controlling the amount of chemicals added so that the value of the water quality control item at the chemical addition point becomes the set value; The setting step includes: setting a management target value for a water quality management item at a target location; The rear end value C of the control table that is closest to the management target value Ｌτ extracting a cell in which the above is stored for each water quality value range, and creating a setting value table using the center value Cn of the front end value range of the cell as the setting value for each water quality value range; a step of acquiring the value of water quality information of the management system and calculating an average water quality value T' during control; a step of selecting a set value corresponding to the water quality value range to which the average water quality value T' belongs by referring to the set value table, and setting the set value as a set value for a control step; A water quality control method comprising the steps of:

6. a control value setting device for performing the setting step; The water quality control method according to claim 5, characterized in that the control value setting device has a recording unit in which at least the control table is recorded, and a control unit that creates the setting value table and determines the setting value of the control step based on the average water quality value T'.

7. a water quality control unit that performs a control step; The water quality control method described in claim 6, characterized in that the water quality control unit includes a control value measurement unit that acquires the value of a control item at the chemical injection point, a chemical injection unit that injects chemicals at the chemical injection point, and a control unit that controls the operation of the chemical injection unit so that the value of the water quality control item acquired from the control value measurement unit becomes the setting value determined by the control value setting device.

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