Method for adaptive overcurrent protection of distribution systems with Distributed synchronous Generators

The increase of Distributed Generators (DG) has encouraged the operation of these generators in islanded mode or intentional islanding. Such operation mode can increase the system reliability, once in the event of network failure the supply of critical consumers will be maintained by the DGs. However, it is necessary to consider that the fault current is considerably reduced when the system is in intentional islanding, and the overcurrent protection setting must be adapted in order to take into account the new fault current level. This paper proposes the use of adaptive protection to change the overcurrent protection setting based on the identification of the system operating state. The system operating state is identified by the use of an active measurement technique, which identifies its operating condition by the impedance level of the grid. Simulation results show that the proposed scheme can be used to update the protection settings for the islanded operation condition.