Energy-based Directional Pilot Protection for Distribution Networks with IBDGs Considering Unmeasured Load Switching

Inverter-based distributed generations (IBDGs) are the main approach to utilizing clean energy in distribution networks (DNs). Compared with synchronous source, fault response of IBDG is very different. As a result, in DNs with high penetration of IBDGs, legacy protection schemes will no longer be applicable. In this paper, an energy-based directional pilot protection scheme suitable for DNs with IBDGs is proposed. This scheme considers the large range of phase angle caused by IBDG integration and uses improved energy polarity criterion to determine fault direction. In addition, magnitude of energy is used to distinguish between faults and load switching to overcome maloperation of directional pilot protection caused by internal unmeasured load switching. The proposed scheme first uses local measured information to determine fault direction sign and then exchanges the direction sign with the remote terminal. This scheme does not require high-bandwidth communication and strict data synchronization, so it can be implemented at a low cost. Finally, simulation studies verify effectiveness of the proposed scheme.