Synchronized re-connection of island operated LV microgrid back to utility grid

Microgrids can be defined as distribution systems with distributed generation (DG) units, energy storages and controllable loads. Microgrids are expected to form an essential part of future Smart Grids with self-healing feature. Most of the time microgrids will be operated normally parallel with utility grid. In addition to this microgrids have a special self-healing capability, because they can continue operation also in island mode during disturbances, e.g., utility grid outages. One important issue which needs to be solved is the synchronized reconnection of island operated microgrid back to utility grid. In this paper issues related to the re-connection of low voltage (LV) microgrid are studied and different functions to enable synchronized re-connection are presented with various DG unit configurations through simulation studies with PSCAD simulation software.