Optimization of reverse-time overcurrent protection for active distribution networks considering bidirectional power flows

High-penetration distributed generators connected to active distribution networks bring bidirectional power flow and variable fault current directions, leading to severe curve mismatch of conventional inverse-time overcurrent protection. This paper presents an optimized inverse-time overcurrent protection scheme for bidirectional power flow. The positive-sequence fault current is extracted to build a virtual current function insensitive to power flow directions, and an adaptive time corrector is designed to dynamically reconstruct protection curves. Simulations prove that the operation time error is within ±3 ms for phase short circuits and single-phase ground faults, with a 100% correct operation rate, effectively resolving protection coordination conflicts from distributed generator integration.