Nosov Magnitogorsk State Technical University (Magnitogorsk, Russia):

A. A. Nikolaev, Cand. Eng., Professor, Head of Dept. of Automated Electric Drive and Mechatronics, e-mail: aa.nikolaev@magtu.ru
P. G. Tulupov, Post-Graduate Student, Dept. of Automated Electric Drive and Mechatronics, e-mail: tulupov.pg@mail.ru

There is a common disadvantage for most modern electric mode control systems of electric arc furnaces and ladle-furnaces, such as HI-REG, Q-REG, ARCOS, Simelt, Melt Expert, Ferrotron, Meltnet, Arcelec, EMPERE, Digitarc. This disadvantage is associated with the absence of technical solutions aimed at complete linearization of the electric and hydraulic circuit of the furnace as a control object. As a result, the system cannot be tuned to the technical optimum over the entire range of working arc lengths. One of the ways to solve this problem is the use of a nonlinear adaptive P-impedance controller, which provides complete linearization of the electrical and hydraulic circuits using special linearizing characteristics. In order to achieve the technical effect, expressed in reducing the dispersion of electric arc currents on different melting stages, it is necessary to select the optimal value of the gain of the adaptive controller. In practice, this problem may be solved iteratively using a mathematical model that makes it possible to form random disturbances along the length of an electric arc, corresponding in their statistical characteristics to real disturbances. Obviously, the signal of the the electric arc current effective value is not stationary and ergodic throughout the entire melt due to constantly changing conditions (for example, furnace transformer tap, reactor tap, the setting of the control parameter, the stage of melting, etc.). As a result, the task of identifying stationary and ergodic sections as part of the electric arc current signal is of particular relevance. Within the framework of the research carried out, a method has been developed for modeling random disturbances of the length for optimal tuning of the impedance non-linear controller.
The research was conducted under financial support of the RF Ministry of Science and High Education (the project No. FZRU-2020-0011).

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