Analysis of series-connected wound-rotor self-excited induction generator

The paper presents theoretical and experimental investigations for steady-state performance of a three-phase wound-rotor series-connected self-excited induction generator (SCSEIG). This type of generator can be realised by series connection of stator and rotor windings of a slip-ring type induction machine. Self excitation may occur when a suitable capacitor bank is connected across the machine terminals. The generator produces an output voltage with a frequency of half the rotor electrical angular frequency and independent of the load conditions provided that the prime mover speed is kept constant. The well known generalised machine theory has been employed with a proper transformation, resulting in a hypothetical equivalent saliency, which produces periodically time-varying inductances needed for such generators (via the mutual coupling between rotor and stator windings). Analysis is achieved by considering saturation effects on both axes (d and q) and theoretical results were found to agree well with corresponding experimental values