External grid representation for assessing fault ride through capabilities of distributed generation units

The existing power systems are challenged as the share at MV distribution level of distributed generation is increasing. In order to ensure the security of operation and power quality in these grids, transmission and distribution power system operators have issued connection and operation guidelines related to integration of distributed generation. Some of these guidelines are designed to assess fault ride-through capabilities when dynamic connection studies are performed for distributed generation units. While most of the ongoing research have addressed especially the fault ride-through capabilities of the investigated generation unit when the most severe fault occur close to the point of common coupling, some research questions remain related to the adequacy of the representation of the external grid. This paper will compare several representations of external grid proposed by different authors for achieving more accurate results of fault ride-through capabilities of small scale hydro units.