Doubly-fed induction generator model for analysis of fault-ride through and asymmetrical generator-side faults

Wind-generated power still becomes more and more important; its contribution to overall energy generation cannot be neglected anymore. Consequently, the grid-code requirements are tightened to guarantee stable operation of the interconnected grid in case of local faults. For this, induction-machine modells are needed which on the one hand allow for precise simulation of fault conditions also inside the generator itself and on the other hand correctly represent the dynamic properties of the doubly-fed induction machine. Known models only allow simulation studies of symmetrical machines. In this paper, a modelling approach for induction machines is introduced which also allows asymmetrical configurations, resulting e.g. from faults inside the machine. In detail, the adhanced DFIG modell is deduced and verified by measurement results. Based on the resulting set of first-order differential equations several fault scenarios are simulated. Also, unsymmetrical machine-side faults are included.