Modeling of stand-alone variable speed diesel generator using doubly-fed induction generator

Diesel generators are widely used to supply electric power to remote and isolated areas where grid extension is prohibitive due to financial and technical constrains. In order to maintain an acceptable efficiency and moderate operation condition, the conventional constant speed diesel generators are designed to run above a specific minimum load requirement, which is normally over 50% of rated power, even though the actual load power demand is low. This results in low fuel efficiency. Operating the diesel generator running under variable speed operation can avoid the defects of conventional constant speed diesel generator. This paper proposed a simulation analysis of a stand-alone variable speed diesel generator that the rotating shaft of diesel engine is directly coupled to a doubly-fed induction generator (DFIG) to obtain an output voltage with constant frequency and constant magnitude. Indirect stator flux orientation vector control strategy is adopted to control DFIG for stand-alone operation and the simulation results are presented and confirm the validity of the strategy.