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Islanding detection of synchronous machine-based distributed generators using signal trajectory pattern recognition

Penetration of distributed generators (DGs) has continued to grow rapidly into power grids and is one of the indispensable aspects of the future smart grid. If a part of the system becomes islanded, DGs should effectively continue to control the islanded power system without degradation of power quality, and otherwise the DGs should be disconnected as soon as they have no adverse impact on the islanded grid. Therefore, the islanding should be detected timely in order to disconnect the DG or change control strategy of the DG. This paper proposes a passive islanding detection method for synchronous DGs based on pattern recognition of signal trajectory. The proposed algorithm provides an accurate islanding detection for future smart grid using intelligent relays. The islanding situation can be discriminated from grid-connected disturbances even when the generation and load are closely matched in the island. The performance of the proposed method has been investigated using PSCAD/EMTDC time-domain simulations in different scenarios.