A harmonic domain computational package for nonlinear problems and its application to electric arcs

A general package for harmonic-domain computation is described. It consists of a set of routines which can be used by developers of programs for power system harmonic applications. The most basic routines have been listed. The package represents nonlinear characteristics by fitting the characteristic with a polynomial, for which special harmonic domain processing via convolutions has been developed, or by directly applying a fast Fourier transform. A model in the form of a differential equation is derived for the electric arc. It is based on simple energy balance considerations and therefore is expected to be generally valid. The computational results compare well with existing measurements. The arc model can be used for discharge lamps or for arc furnaces.