Automatic Islanding Control of Radial Distribution Systems with Distributed Generation

The islanded operation of part of the distribution network fed by Distributed Generation (DG) can be valuable for the utility, the customers and DG owners. For the utility it can represent reduction of expenses due to blackouts, for the customers it can represent better supply service and DG owners can benefit from better availability of distribution network. Even with many challenges for safe operation, namely personnel safety and power quality, most of them can be surpassed by studying the network previously and supervising the behavior of the network in the case of a possible islanding. This paper presents an Automatic Islanding Control System (AICS) that encompasses automation and protection schemes and can be applied to radial feeders where MW-scale synchronous generators based DG are connected. The studies that must be performed in advance to be incorporated in the AICS algorithm, as well as an evaluation of the communication requirements, are described in detail. The presented system is being applied to an actual rural distribution network at Rio de Janeiro, Brazil, and the results show that the automatic islanding is viable for a large range of operating points.