Equivalent Circuit and Induction Motor Parameters for Harmonic Studies in Power Networks

An induction motor model for high harmonics used in literature for harmonic penetration studies and the corresponding parameters are analyzed in this paper. It is shown that the rotor slot resistance and the rotor slot reactance values are equally in the short circuit regime and that they have practically equal values, in per unit, for all motors of the same series. The knowledge of the equivalent circuit parameters of the squirrel-cage induction motors operating in the short circuit regime is especially important when calculating the current power losses in induction motors supplied from power set with high harmonics. General conclusion is that harmonic reactance values used in literature are more or less accurate (or by 10% higher). On the contrary, real resistance values are 2 similar to 4 times higher and the active powers absorbed by the rotation machine do not exactly correspond to the damping value. Consequently, the amplification factor of the source harmonic current calculated in literature for resonant regimes is 2 similar to 4 times higher than the real values.