Two-phase high-performance control of a reliable stand-alone induction generator

The study presents a significant development of an advanced control strategy for stand-alone three-phase induction generators. The system under study consists of a squirrel-cage induction generator driven mechanically by an internal combustion engine and electrically by a fault-tolerant converter coupled with a LC filter. As a novelty, in this study three low-cost electrical contactors are introduced in order to re-arrange the converter topology after a fault occurrence and a proper re-starting procedure is developed, allowing the converter to operate with only two legs. The control architecture is mainly described with respect to this last operating condition, evidencing its intrinsic robustness. The study focuses on the composite control of the converter and the prime mover in order to improve the dynamic assessment of the whole system. The converter control is designed around the sliding mode technique, due to its attractive performance, especially as far as parameter uncertainties are concerned. In order to validate the theoretical framework, this study presents the first ever made experimental tests of this system with reference to a generation unit of about 10 kVA. The results confirm the high capability of the proposed system in regulating voltage and frequency with very good dynamic features.