Ultra fast protection of radial and looped electric power grid using a novel solid-state protection device

Exploiting the fast operation of solid-state Fault Isolation Devices (FIDs), this paper presents a novel over-current protection scheme for radial and looped electric power distribution systems. The main feature of the proposed protection scheme is that it ensures the maximum restoration of the system in less than a quarter of the electric cycle. Due to the inherent characteristics of the solid-state devices, the FID is also able to limit the fault current to the maximum allowable fault current level of the system, thus reducing the thermal and mechanical stress on transformers and other power system equipments. Using the inherent characteristics of the solid state devices, a novel fault detection criteria is also proposed that eliminates the necessity of the current sensor or transformer (CT) for detecting the over-current fault. These advantages are all achieved without requiring communication between FIDs. Performance of the FID with the proposed protection scheme is demonstrated based on an all-analog logic-level grid-voltage scale experimental setup. The experiments demonstrate the capability of the proposed protection scheme to fulfill the demands of highly inter-connected electric power distribution systems.