Analysis and control of three-phase self-excited induction generators supplying single-phase AC and DC loads

An approach employing genetic algorithm (GA) has been evolved for the analysis of single-phase operation of three-phase self-excited induction generators. Using symmetrical components, the circuit equations have been written and an impedance matrix has been derived, which can be straightaway solved using this method. The lengthy derivations of nonlinear equations required for the unknown variables, in the earlier methods, are thus not required in the present method. Apart from single-phase AC loads, feeding of DC loads through a controlled rectifier has also been considered and the analysis has been extended for this combined loading. For maintaining a desired DC voltage on the rectifier output side, symmetrical and extinction angle control techniques have been adopted. These techniques are shown to be better compared to the conventional phase angle control, in improving voltage regulation of the generator. The suitability of each of these control schemes for specific load conditions is discussed with examples. A biomass gasifier-based diesel engine has also been used as a prime-mover and the experimental results obtained on two generators with AC as well as DC loads, closely agree with the values predetermined using the GA approach.