FREQUENCY ESTIMATION DEVICE, METHOD AND PROGRAM IN MOLTEN METAL SURFACE LEVEL CONTROL SYSTEM OF CONTINUOUS CASTING MACHINE

PROBLEM TO BE SOLVED: To allow a frequency component of periodic disturbance causing fluctuation of molten metal surface level to be estimated accurately and with high responsiveness.SOLUTION: A frequency estimation device 108, which estimates a frequency component of a periodic disturbance causing fluctuation of molten metal surface level, in a molten metal surface level control system that detects the molten metal surface level inside a mold during operation of a continuous casting machine and controls the molten metal surface level y to be maintained at a target level r using deviation between the detection level and a predetermined target level r, comprises: an initial frequency searching portion 108a that inputs a signal of the detection level y or a signal required depending on the detection level y to estimate frequency by the iterative least squares technique; and a nonlinear optimization portion 108b that inputs the frequency estimated by the initial frequency searching portion 108a to estimate the frequency component of periodic disturbance causing fluctuation of the molten metal surface level by a nonlinear optimization technique.