Distributed Power Generation : A micro-grid control system including an automatic "Virtual Islanding" mode which enables a smooth transition from a grid-connected to an islanded state

Distributed power generation systems generally comprise a number of power sources and electrical power loads interconnected by a distribution network. Electrical switches and fuses are provided such that local groups of power sources and power loads can be established. Should there be a degradation in the distribution network in terms of a set of criteria such as electrical frequency, current or voltage then the switch or fuse may be thrown to establish each local group as an island. By monitoring divergence from a set of criteria a method and controller may be utilised whereby the distribution network as a whole is considered and configured to establish virtual islands which operate prior to the establishment whether inadvertently or deliberately of actual islands within the distribution network.; In such circumstances the transition from normal operation for the distribution network to islanded operation for the distribution network is less severe