Single-phase operation of a three-phase induction generator using a novel line current injection method

By using two capacitances and a current injection transformer, a three-phase induction generator can operate with good phase balance and line power factor while delivering power to a single-phase power grid. This paper presents a systematic analysis on this novel induction generator configuration. The solution of the system´s inspection equations using the method of symmetrical components enables the steady-state generator performance at any speed to be computed. The conditions for achieving perfect phase balance are deduced from the phasor diagram. It is shown that the capacitances that result in perfect phase balance depend on the generator admittance, power factor angle, as well as the turns-ratio of the current injection transformer. Where possible, the computed results are verified by experiments conducted on a 2-kW induction machine. An experimental investigation on the system waveforms and harmonics is also carried out.