Some pecularities of the fault current contribution by dispersed generation

The impact of several technologies of dispersed generation on the fault current flow in regular distribution networks is discussed. The short-circuit current behavior of conventional generators (for instance those used in heat and power plants), of generators equipped with full convertors and of double fed induction generators (DFIG) are described from the perspective of a distribution system operator (DSO) with limited information about the power plants. Special attention is given to variable speed generators; i.e. equipped with power electronic devices. Default figures are given for the assessment of the short-circuit current contribution by dispersed generators to a fault in a MV grid. Measurement results from real short-circuit tests with variable speed generators in a network are shown.