Re-Synchronization control strategy for master-slave controlled microgrids

In this paper, a resynchronization control strategy for a master-slave controlled microgrid has been developed. In the proposed control scheme only the generator acting as the master for the isolated microgrid is responsible for its resynchronization. The derived controller consists of two different control loops: active and passive. The first one consists in forcing the master unit to adjust its active and reactive power outputs to rapidly adapt the overall system frequency and voltage magnitude to the reference signal. On the contrary, the passive method waits that the two sets of voltage phasors at both microgrid and utility grid sides are synchronized before enabling the master unit to start the resynchronization process. Experimental tests have been performed on the PrInCE Lab microgrid built at the Polytechnic University of Bari, Italy, in order to prove the effectiveness of the proposed controller..