Fault Type Classification in Microgrids Including Photovoltaic DGs

Protective devices of smart and fault-resilient microgrids are not expected to trip the healthy phases during unbalanced short-circuits. Thus, some utilities and relay manufacturers have started contemplating single- and double-pole tripping for distribution systems. Selective phase tripping demands fault type classification. This paper reveals that existing industrial methods misidentify the fault type in microgrids that include photovoltaic distributed generations (DGs). Due to interface similarities, this paper pertains to systems with type IV wind DGs as well. Two new classifiers proposed in this paper determine the fault type accurately for not only microgrids with photovoltaic DGs, but for any three-phase system. With low computational burden, they require only local information and operate successfully for high resistance faults. Furthermore, these techniques are not affected by the system imbalance and different DG power factors over disturbances.