Theoretical basis of energy efficiency criterion-based optimal control of arc steel-melting furnace modes taking into account 3-dimensional phase current distribution

The purpose of the article is to develop a method for synthesis of the operative adaptive optimal control of the electric mode (EM) of an arc steel-melting furnace (ASF) by energy efficiency criteria based on three-dimensional (3-D) distribution of arc currents. The basis of the created method is the use of operative information on the parameters of 3-D distribution of arc currents and the search for the appropriate optimal control – set points for arc currents of a double-loop system of controlling the electric mode of an arc steel-melting furnace. There have been obtained partial optimality criteria to minimize the specific energy consumption, the steel price per ton, and to maximize the hourly productivity of an arc furnace, as well as an algorithm for operational synthesis and implementation of the optimal control vector according to the chosen criterion, taking into account the model of 3-D current distribution. For the first time, based on the operative on-line control of 3-D arc currents distribution, partial criteria have been obtained for the synthesis of adaptive optimal control of the electric mode of an arc furnace, which makes it possible to comprehensively improve the energy efficiency and electromagnetic compatibility of the arc furnace modes and the electric supply network. The implementation of the created method of adaptive optimal control and the algorithm for its implementation in the structure of a double-loop control system of electric melting mode will allow us, in comparison with the known single-loop control structures, to improve the indices of electrotechnological efficiency and electromagnetic compatibility, and to obtain higher dynamic accuracy of stabilization the electric mode coordinates at the level of the operatively synthesized optimal arc current set points.