[pt] Esta tese apresenta os principais fenômenos eletromecânicos, que ocorrem durante a operação do forno a arco, com ênfase especial nos fenômenos elétricos e magnéticos envolvidos. Apresenta também uma simulação computacional, que tem por objetivo verificar que a utilização de um reator série limitador de corrente no circuito de alimentação do forno, visando estabilizar o arco, não reduz significativamente a potência operacional do mesmo à 60Hz. A tese apresenta ainda os resultados de uma simulação analógica, que permite verificar que a impedância do reator série limitador, vista pelo circuito do forno, é pequena à 60 Hz e relativamente elevada em outras freqüências. Desta forma, tem-se um efetivo amortecimento das flutuações de corrente e tensão, causadas pela operação do forno, sem restringir a potência operacional do mesmo. / [en] This thesis presents the main electromechanical phenomena, occuring during the operating of an arc furnace, focusing the electric and magnetic ones. It also presents a digital simulation aiming to verify that the utilization of a series limiting current reactor included into the furnace feeding circuit, for arc stabilization purposes, does not reduce its operational capacity at 60 Hz. It is also presented the results of an analogic simulation, which shows that the reactor impedance seen by the furnace circuit is small at 60 Hz and relatively large at other frequencies. Hence, an effective damping of the current and voltage variations, caused by the furnace operation, can be achieved.

Distributed Series Reactors (DSRs) can be used to control power flow to more fully utilize the capacity of a transmission network, delaying investment in new transmission lines. In this study the IEEE 39 bus standard test system is modified to a 3-phase, unbalanced model consisting of 230 kV, 345 kV and 500 kV lines, where lines of different voltage run in parallel. This model is used to study load growth and the effect of adding DSRs to alleviate resulting overloads, and in particular to alleviate overloads on lines of different voltage running in parallel. The economic benefit of adding DSRs to the network is compared to the addition of new transmission lines in the network. In the second part of the work, the effect of unsymmetrical operation of DSRs on a single transmission line is studied and compared to the symmetrical operation of DSRs. It is found that the unsymmetrical operation of DSRs is more economical. Finally the unsymmetrical operation of DSRs to reduce voltage imbalance in the network is considered. / Master of Science