JPH1161893A - Controller for water-supply plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a water-supply plant, with which the water supply-plant can be efficiently operated under control in accordance with an actual situation without the necessity of an expert operator. SOLUTION: A water demand estimating means 23 estimates a water demand in accordance with actual results of past water demand stored in a water demand result storing means 31. A water-supply plant operation planning means 24 formalizes and solves an operation planning optimization problem having a plurality of objective functions relating to the operation of the water-supply plant so as to obtain operation planning values. A water-supply plant control means 25 controls the operation of the water-supply plant in accordance with the operation planning values obtained by the water-supply plant operation planning means 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a waterworks plant, and more particularly to a control device for a waterworks plant capable of performing an efficient operation according to the actual situation.

[0002]

2. Description of the Related Art Generally, in a water supply facility, purified water is generated by a water supply plant, stored in a buffer (reservoir), and supplied to customers as needed. In this case, by generating purified water at night and supplying purified water stored together with the purified water during the day, efficient operation such as effective use of nighttime power and peak power cut during daytime is possible. Become.

However, in order to perform such an operation in consideration of efficiency, it is necessary to secure the number of specialized operators. That is, in order to perform the operation in consideration of the efficiency, a comprehensive automation technology based on the expert knowledge of an intelligent operator is required, but in reality, it is not realized at present.

[0004]

As described above, in the prior art, efficient operation of a water supply plant cannot be performed unless a specialized operator is secured.

[0005] The present invention has been made in view of such a point, there is no need to secure a specialized operator, and a control apparatus for a waterworks plant that can automatically operate the waterworks plant efficiently. The purpose is to provide.

[0006]

According to the present invention, there is provided a water supply plant control device for controlling a water supply plant, wherein the water demand record storage means for storing past water demand records and the water demand record storage means for storing the past water demand records. Water demand forecasting means for statistically predicting water demand based on the actual water demand, and a plurality of water supply plant operations based on water demand forecast values predicted by the water demand plant parameters and the water demand forecasting means. While formulating the operation plan optimization problem with the objective function of, the water supply plant operation planning means for solving the operation plan optimization problem to obtain the operation plan value of the water supply plant, and the water supply plant operation planning means Water supply plant control means for controlling a water supply plant based on a plant operation plan value. It is a prediction control unit of the plant.

According to the present invention, first, the water demand is predicted by the water demand prediction means based on the past water demand results stored in the water demand performance storage means. Next, an operation plan optimization problem having a plurality of objective functions relating to operation of the water supply plant is formulated and solved by the water supply plant operation planning means based on the parameters of the water supply plant and the predicted water demand. Thus, the water supply plant operation plan value is obtained.

The water supply plant operation planning means controls the operation of the water supply plant based on the operation plan values.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a control device for a waterworks plant according to the present invention. FIG. 1 is a schematic diagram of a control device for a waterworks plant.

As shown in FIG. 1, the waterworks plant has a water treatment plant 1 and a buffer (water distribution reservoir) 5 for storing purified water produced in the water treatment plant 1 and having a water level gauge 6 attached thereto. This water purification plant 1 generally has a plurality of water pumps 2
The purified water sent from the water treatment plant 1 by the water pump 2 is stored in the buffer 5 through the water pipe 4 to which the flow meter 3 is attached, and then to the customer 9 through the water distribution pipe 8 to which the flow meter 7 is attached. Supplied.

On the other hand, the control device 11 of the water supply plant
A process input / output unit 22 for exchanging signals with a water supply plant, a water demand record storage unit 31 for storing past water demand records, and a water demand record based on the water demand records from the water demand record storage unit 31. Demand forecasting means 2 for forecasting
3, a water supply plant operation planning means 24 for obtaining a plant operation plan value from a water supply plant parameter and a water demand forecast value, and a water supply plant control means 25 for controlling the operation of the water supply plant based on the plant operation plan value. . The water supply plant operation planning means 24 is connected to a water supply plant parameter storage means 32 and a human interface input / output unit 21.

The process input / output unit 22 inputs a measurement signal of the water supply plant and outputs a control signal to the water supply plant. The water demand result storage means 31 constitutes the water demand result storage means 12 and stores the past water demand results together with the time and day of the week. The water demand prediction means 23 comprises a water demand result storage means. 31 based on the actual water demand
It statistically predicts water demand.

Further, the water supply plant operation planning means 24
Is the water supply plant parameter storage means 3 as described above.
The operation plan of the water supply plant is obtained based on the parameters of the water supply plant stored in 2 and the predicted water demand value predicted by the water demand prediction means 23. Based on the water supply plant operation plan value obtained by the planning means 24 and the water supply plant measurement signal input from the process input / output unit 22, a control signal for controlling the operation of the water supply plant is sent to the process input / output unit 22. Output.

The parameters of the water supply plant are input from the human interface input / output unit 21 to the water supply plant parameter storage means 32.

Next, the operation of the control device for a water supply plant having such a configuration will be described.

In FIG. 1, the actual water demand value obtained through the flow meter 7 is separated as an actual water demand through a process input / output unit 22 by internal signals such as time and day of the week. It is memorized.

Next, on the basis of the actual water demand stored in the actual water demand storage means 31, a predicted value of the water demand for the first N hours is obtained by the water demand prediction means 23. Next, the water supply plant operation planning means 24 uses the water supply plant parameters from the water supply plant parameter storage means 32, such as the capacity of the buffer 5 and the rated capacity of the water pump 2, and the predicted water demand value from the water demand prediction means 23. Thus, operation plan values for the previous N hours can be obtained. Then, the water supply plant control means 25 controls the operation of the water supply plant by inputting a process signal from the process input / output unit 22 as a feedback signal in accordance with the obtained water supply plant operation plan values for the preceding N hours.

In the following, a specific operation of this point will be described. Here, for simplicity, it is assumed that the prediction and the plan are N = 24 every hour.

First, water demand prediction is performed as follows. Water demand data for one day every hour is filed in the water demand result storage means 31 for each day of the week, for example, for holidays, weekdays, and special days. Next, in the water demand forecasting means 23, when the day of the week is input from the human interface input / output unit 21, the average value pattern of the day of the week w is input.

(Equation 1) Is obtained.

Next, assuming that the water demand results of the previous day were obtained,
In order to predict the water demand on day k, for example, the following autoregressive model is used.

(Equation 2) Becomes

A1, a2,... Are autoregression parameters, which can be given in advance or can be sequentially estimated in real time by least-squares (Kalman filter).

(Equation 3) Is obtained.

Next, the water supply plant operation plan value is calculated by the water supply plant operation planning means 24 based on the parameters from the water supply plant parameter storage means 32 and the water demand prediction value from the water demand prediction means 23 as follows. Is required.

First, consider minimizing the sum of the following three objective functions.・ Electricity charges ・ Stable operation of waterworks plants ・ Peak cut during the daytime

Now, the operation state of the water supply pump 2 (the number of water supply pumps is k) of the water supply plant at the discrete time n is represented by X (n) = [X1 (n) _... Xk (n)] T: Water supply pump ON / OFF vector ... (4) The rated discharge flow rate of the water supply pump per unit is x (n) = [x1 (n) _... xk (n)] T: Water supply pump quantization vector ... (5) Reservoir ( X # (n) = [x # 1 (n) _... X # m (n)] T: Reservoir water storage vector... (6) . Here, T means transposition.

Each constant is defined as follows. a = [a1 _... ak]: unit vector ... (7) w = [w1 _... wk]: ON / OFF penalty vector of water pump ... (8) Q (i) = [Q (1) _... Q (n) _{) ... Q (24)] T} : water demand vector ... (9)

(Equation 4) And Also, CD: general power rate [yen / kwh] CP: power rate in the peak cut time zone [yen / kwh] stt: start time of power peak cut stp: end time of power peak cut In addition, the constraint is

(Equation 5) And At this time, the optimization problem for minimizing J can be formulated as an integer programming problem, and by solving this problem, it becomes possible to make an operation plan for the water pump.

In the present embodiment, as shown in FIG. 2, this integer programming problem is described by a genetic algorithm (G
A: Solve using Genetic Argorithums).

<Step 1> At time i, the ON / OFF of the water pump is represented by the following 0/1 bit string. 1234... Kk: Number of pumps X (i): [1110... 0] These are made from time 1 to time n and represented as one bit string.

[0029]

(Equation 6) This bit string is called an individual. The number of individuals can be arbitrarily selected, but is r in this case.

<Step 2> For each individual, an evaluation function (objective function) (12) is calculated based on the aforementioned constraints (16) to (18). This calculated value is called fitness. The fitness of an individual who does not satisfy the constraint condition is given a very large value.

<Step 3> The fitness of each individual is obtained as a ratio to the sum of all individuals. From the individuals with a small ratio, only r pieces are preferentially left in the next generation. Others are eliminated.

<Step 4> A set of two individuals (parents) is selected at random, a certain position of the bit string is randomly determined, and the individuals are divided into subsequences there. Subsequences are replaced for each set This operation is called crossover. By the crossover, two new individuals (children) are generated. Individuals that failed to participate in the cross are eliminated. However, it is assumed that the operation of dividing into partial columns at the crossover is performed for each bit sequence corresponding to each time (see FIG. 2).

<Step 5> At each time point, one bit is randomly selected from the subsequence of each individual, and 0
Invert / 1. This is called a mutation (see FIG. 2).

<Step 6> The average of the fitness of this generation is obtained, and the difference from the average of the fitness of the previous generation is calculated. If the difference is equal to or less than a certain value, the individual having the minimum fitness is adopted as a solution, and the algorithm ends.

As described above, the water supply pump operation status X (n) of the water supply and sewage plant for 24 hours is optimized for each hour based on the predicted water demand value obtained by the equation (2) using the genetic algorithm. Be planned.

Next, the operation of the water supply plant is controlled by the water supply plant control means 25 as follows.

(A) When the accumulated error of the predicted water demand value obtained by the equation (2) is within an allowable range, the water pump is designed as planned on the basis of the reservoir reservoir target value per hour. 2
Is controlled.

(B) When the accumulated error of the predicted water demand exceeds the allowable value, if the time required to achieve the target reservoir water storage amount can be changed only within the preceding m hours, the number of units can be controlled. The timing is shifted, and the number control is executed when the reservoir storage amount target value is reached. If it is necessary to start a new water pump within the previous m hours, or if it is planned but does not need to start the water pump, the plan is corrected by starting or continuing.

In order to execute these controls, in addition to the scheduled load prediction, the water demand prediction means 23 performs the following water demand prediction m hours later. That is, if the day of the week is W, the average hourly water demand on that day

(Equation 7) Here, b1, b2,... Are auto-regression parameters, which can be given in advance similarly to a1, a2,.

By using the water demand forecast value thus obtained, the water supply plant control means 25 turns on / off the water supply pump of the water supply plant within the preceding m hours.
Whether or not the OFF is required other than in the plan can be easily determined.

(C) When the accumulated error in the water demand forecast has returned to within an allowable range. At this time, in the water supply plant control means 25, the operation control based on the operation plan value of the water and sewage plant described above is executed again, and a re-plan is made.

As described above, the control device for the water supply plant according to the present embodiment includes a process input / output unit 22 that inputs a measurement signal of the water supply plant and outputs a control signal to the water supply plant, Water demand result storage means 31 for storing demand (temperature, flow rate, etc.) results together with time and day of the week, and water demand statistically predicted based on water demand results stored in water demand result storage means 31 Based on the water demand prediction means 23, the parameters stored in the water storage plant parameter storage means 32, and the water demand forecast values predicted by the water demand prediction means 23, the operation plan of the water supply plant is optimized by a genetic algorithm as an optimization technique. Water supply plant operation planning means 24 for obtaining a water supply plant operation plan value, and water supply plant operation planning means 24 A water supply plant control means 25 for outputting a control signal for controlling the water supply plant to the process input / output unit 22 based on the operation plan value and the measurement signal of the water supply plant input from the process input / output unit 22 It was done.

Therefore, it becomes possible to perform planned water storage using nighttime power in anticipation of daytime water demand, and it becomes possible to systematically cut off daytime power peaks. In addition, even if the water demand forecast, which is the prerequisite for systematic operation, has an error, the number of water pumps in the water supply plant can be controlled for stable supply, enabling efficient automatic control. Becomes

In the above embodiment, a case has been described in which the water demand forecasting means 23 uses an autoregressive model when forecasting water demand. However, the weather forecast of the day input from the human interface input / output unit 21 is used. Water demand forecasting may be performed using a multiple regression model with values as input.

That is, the algorithm for predicting the water demand and the algorithm for controlling the waterworks plant in the water demand prediction means 23 are not limited to the equations (2) and (19), respectively.
A multiple regression model of the following equations (20) and (21) may be used.

[0046]

(Equation 8) Here, yw (k), a1 and a2 are b1,
b2, ...: parameters, u1, u2, ...: weather forecast values (temperature, weather, etc.) of the day.

By using such a multiple regression model, it becomes possible to absorb daily errors and improve control accuracy.

In the above embodiment, the water supply plant operation planning means 24 employs an optimization method of (4)
The case of using the integer programming method and the genetic algorithm using Expressions (18) to (18) has been described. However, the present invention is not limited to this. For example, a heuristic method, an expert system, fuzzy, or the like may be used as an optimization method Is also possible.

Next, another embodiment of the present invention will be described.

In a sewage treatment plant, when the weather is fine, there is a fluctuation in the inflow of sewage in proportion to the demand for purified water. In order to treat this sewage biochemically, a smooth operation is desired in the sewage treatment process. In the above-described embodiment, an example of application to a water supply system has been described. However, if water demand is considered as the amount of inflow of sewage, it is possible to predictively control a pump for a sewerage plant in fine weather on exactly the same principle.

Although the above embodiment has been described on the assumption that there is one water supply plant, the control of the water supply plant according to the present invention can be performed even when there are a plurality of water purification plants and a plurality of customers. .

[0052]

As described above, according to the present invention, a waterworks plant can be automatically operated efficiently according to the actual situation. In this case, it is not necessary to secure many specialized operators.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a control device for a waterworks plant according to the present invention.

FIG. 2 is a diagram showing an outline of a genetic algorithm in a water supply plant operation planning means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water purification plant 2 Water supply pump 3,7 Flow meter 4 Water supply pipe 5 Buffer 6 Water level gauge 8 Water distribution pipe 9 Customer 11 Predictive control unit 12,31 Water demand result storage means 21 Human interface input / output unit 22 Process input / output unit 23 Water demand forecasting means 24 Waterworks plant operation planning means 25 Waterworks plant control means

Claims (2)

[Claims] 1. A water supply plant control device for controlling a water supply plant, comprising: a water demand result storage means for storing past water demand results; and a water demand result stored in the water demand results storage means. Water demand forecasting means for statistically predicting water demand, and an operation plan optimization having a plurality of objective functions related to the operation of the waterworks plant, based on the parameters of the waterworks plant and the predicted water demand predicted by the water demand forecasting means. A water supply plant operation planning unit that formulates the water supply plant problem and obtains a water supply plant operation plan value by solving this operation plan optimization problem, based on the plant operation plan value obtained by the water supply plant operation planning unit, Water supply plant control means for controlling a water supply plant; . 2. The control system for a water supply plant according to claim 1, wherein said water supply plant operation planning means solves the operation plan optimization problem using a genetic algorithm.