Generalized symmetrical components for periodic non-sinusoidal three-phase signals

This paper deals with the generalization of the symmetrical components technique to periodic non-sinusoidal three-phase currents and voltages. The generalization of the concept of symmetrical components is discussed together with their derivation in both time- and frequency domain. The main conclusion of the paper is that an orthogonal decomposition of periodic nonsinusoidal three-phase signals into positive sequence, negative sequence and zero-sequence components is not possible, but that an additional current and voltage component should be introduced which is called the residual component.