Разработка усовершенствованной методики расчета параметров фильтрокомпенсирующих цепей статического тиристорного компенсатора электродуговой печи

Abstract

Relevance. A lot of Russian as well as foreign metallurgical feature electrical steel-mashing complexes based on electric arc furnaces (EAF) and ladle furnaces (LF). These steel-making units generate high-power electrical load, have non-linear volt-ampere characteristics and leaping unbalanced load variation. For this reason, an operating EAF aggravates power quality and causes an increase in the reactive power factor on the incoming feeders of the main electrical substations. To provide for the appropriate power quality and voltage stabilization on the primary side of the furnace transformer, the additional reactive power compensation devices are used. More than 85% of reactive power compensators for EAF and LF are currently released as static var compensators consisting of a thyristor- controlled reactor (TCR) and filter circuits (FC). The analysis of the rated parameters of SVC produced by different companies shows that there is no universal selection method for the harmonic filters configuration. In that regard, a pressing task is to develop a complex approach to determine an optimum configuration of harmonic filters, provided that its their rated power is known. Research objective: developing the improved method used to select the parameters of filter circuits of SVC for electric arc furnace, accounting for different relevance criteria such as: the cost of FCs, active power losses in harmonic filters, filtration coefficient, and the total harmonic distortion of voltage. Methods: experimental arrays of electrical parameters saved on existing electrotechnical complexes “EAF-SVC” and the methods of mathematical modeling of SVC and EAF. Novelty: the suggested developed method of SVC’s filter circuits parameters selection is original as it features the distribution of the total reactive power using the group optimal criteria, which provides for the best technical and economical indexes of FC, as well as accounting for the peculiar features of a certain steel-making unit and its power supply system. This method is also more accurate in terms of analysis of the electrical regimes of FC as it uses real instantaneous current of EAFs of different classes and power. Research outcomes: 1) the executed analysis of parameters of existing SVC produced by different companies; 2) the existing methods of distribution of total reactive power between harmonic filters have been analyzed; 3) the improved mathematical model of complex “EAF-SVC” allowing for the detailed studies of FC operation modes taking into account the real EAF’s current been mode; 4) the patterns of variation of filtration coefficient for different variants of distribution of total reactive power between harmonic filters have been determined on the basis of mathematical model; 5) the improved method of calculation of SVC’s FC providing for the optimum distribution of reactive power between the harmonics filters taking into account a group of different optimal criteria has been developed. Practical significance: the results have significant theoretical importance for electrical engineering of arc furnaces and may be employed in the calculation of static var compensators in power supply systems of steel-making complexes.