Mikihiko Ohnari

Experience in installing a computer control system in a hot strip mill

It is highly desirable to reduce the application period of a computer control system to a hot strip mill. Completion of a hot strip mill computer control system chiefly depends upon the time when slab tracking is operative, and on the setup calculation method and its checking method. For slab tracking, many support programs were devised such as dump, on-line monitor, process input-output simulator, and mill line simulator. To confirm the efficiency of the setup calculation method, a unique checking procedure has been developed and has proven to be quite effective. With these preparations for the installation of a computer control system in Sumitomos 80-inch hot strip mill, it took only five months in the field to put the full system into operation.

Optimal Operation of a Multireservoir During Flood Periods

Abstract The main problem in applying conventional multireservoir operation principles lies in the difficulty of precise inflow prediction. In this paper, an optical multireservoir operation principle with real-time correction for inflow prediction error is proposed. The optical regulator design method is applied in order to utilize its state feedback characteristics. Results of numerical analysis show that the peak flow of the flood can be decreased and the occurence of the peal: delayed. Moreover, real-time correction of the discharge rate decreases the unexpected water level rise, even when the inflow prediction error is significant.

A Reliable Scheme for Controlling Large Scale Plants and its Application to Multiple Reservoir Operation

Abstract A practical decentralized control scheme is proposed in order to realize reliable large scale control systems. In the present paper, firstly a decentralized control scheme is derived based on an optimal regulator design theory, where interactions among the subcontrollers are predicted by mutual independent parmeter adaptive models. Secondly, an actual multiple reservoir operation problem is considered as an application of the proposed scheme. Numerical study shows the scheme has enough capability to deal with flood inflow. Finally, degree of the reliability enhancement is discussed and it is concluded that the scheme permits a highly reliable system configuration because of its uniform and autonomous structure.

Development of a Reservoir Control Method with the Aid of Unsteady Flow Dynamics Simulation

Abstract A method of designing a reservoir control system which uses unsteady flow dynamics simulation is described. The effect of water level fluctuation on reservoir control can only be evaluated through analysing unsteady flow dynamics. A numerical analysis approach is chosen because of the difficulty in solving the unsteady flow dynamics equation analytically. A special purpose FORTRAN simulation system named RCSS, i.e. River Control Simulation System, is developed. In this system the numerical analysis program of the unsteady flow dynamics equation is installed. With the aid of RCSS, a new reservoir control method is derived. This method makes it possible to maintain water volume at a desired value. Kalman filters are used to get the closest estimate of water volume due to corruption of water level data by various noises. This newly developed control method has proven effective in reservoir control.

DEVELOPMENT OF A RESERVOIR CONTROL METHOD WITH THE AID OF UNSTEADY FLOW DYNAMICS SIMULATION

A method of designing a reservoir control system which uses unsteady flow dynamics simulation is described. The effect of water level fluctuation on reservoir control can only be evaluated through analysing unsteady flow dynamics. A numerical analysis approach is chosen because of the difficulty in solving the unsteady flow dynamics equation analytically. A special purpose FORTRAN simulation system named RCSS, i.e. River Control Simulation System, is developed. In this system the numerical analysis program of the unsteady flow dynamics equation is installed. With the aid of RCSS, a new reservoir control method is derived. This method makes it possible to maintain water volume at a desired value. Kalman filters are used to get the closest estimate of water volume due to corruption of water level data by various noises. This newly developed control method has proven effective in reservoir control.

Quasi-Optimum Routing System for Pump Operation Scheduling

Abstract Recently, water transport systems require the economical operation of pumps. A new practical method is proposed for determining the number of pumps to be operated when the pumping rate is varied by on-off control of pumps. This method designates quasi-optimum solutions which minimize the on-off frequency and/or energy consumption. To obtain these solutions, a heuristic algorithm is employed. It is simplified by treating the predicted load and pumping rate cumulatively along a time axis. This method is advantageous over conventional methods in that the calculation time is shorter, a smaller memory is required and that mini-computers are applicable. Economical automatic operation can be realized by combining this method with various load prediction techniques.

Two Types of Setup Models Applied to Computer Control of Hot Strip Mills

Abstract In a computer control system for a hot strip mill, the mill setup function plays a major role in improving on-gage percentages. The methods of mill setup are roughly divided into two categories. The first is a stored schedule setup, and the second is a calculated setup using a mathematical model of rolling process. Two typical types of calculated setup are the absolute method and the incremental method. Both types of calculated setup methods were utilized in the course of system construction. This paper mainly discusses their composition and mathematical models.