1993 Volume 113 Issue 3 Pages 381-386
The induction of zero-phase-sequence voltage by negative-phase-sequence current in a salient pole synchronous generator is proved experimentally and theoretically. In the method of symmetrical coordinates, it has been believed that positive-, negative- and zero-phase-sequence components are independent. But an experiment driving a synchronous generator with unbalanced load shows that zero-phase-sequence voltage is induced when only negative-phase-sequence current is applied. The amplitude of the induced voltage is proportional to that of the current. The phase difference between the voltage and the current is not constant, but the sum of phases is constant. So, relation between the voltage and the current is not represented with the impedance. The induction of zero-phase-sequence voltage is proved theoretically by magnetic flux distribution in the air-gap of synchronous generator. The m. m. f. by negative-phase-sequence current generates the space 3rd harmonic flux distribution by the saliency of the rotor and the field current 2nd harmonics. This flux distribution component interlinks the space 3rd harmonics of the armature winding distribution and induces zero-phase-sequence voltage.