Transient short-circuit behaviour of distributed energy sources and their influence on protection coordination

This paper presents the results obtained by research on the influence of distributed generation (DG) on protection in the distribution network. Generation connected to the grid is subject to protection regulations. Applying the present regulations to distributed generation results in unnecessary disconnection of these distributed generators. This may lead to problems at a high penetration level of distributed generation, e.g. a long-term disturbed voltage level in the grid. Thus revision of the present protection coordination is necessary. To investigate the effect of different protection schemes, a dynamic model of a distribution network is designed. This model is implemented in DIgSILENT PowerFactory for dynamic studies. The research shows that it is possible for DG to ride-through a fault in an adjacent feeder. It is also provides a protection scheme for DG that distinguishes a fault in an adjacent feeder and a fault in the same feeder as the DG. By applying this scheme unnecessary disconnection of DG will be avoided.