Harmonics, interharmonics and unbalances of arc furnaces: a new frequency domain approach

The complexity of nonlinear models for simulating the dynamic behavior of arc furnaces is well known. For this reason, previous works are based on time domain solutions. In this paper, a new frequency domain approach for obtaining harmonics, interharmonics and unbalances of arc furnaces is proposed. The model assumes a dynamic and nonlinear u-i characteristic of the electric arc as well as continuous evolution of the arc current. The lowest interharmonic frequency to be represented imposes the duration of the "reference period". Each reference period consists of "N" elemental cycles. The model is described by general equations where the parameter "N" can take any value. The implementation of these equations in a computer program is straightforward, providing very fast calculations for interharmonic components. Finally, the extension of harmonic power flows to interharmonic frequencies is evaluated.