Active protection method of single-phase fault for distribution network considering fault ride-through of distributed generator

The impact of single-phase grounding faults in distribution networks on equipment and personal safety is becoming increasingly severe. However, due to the limited short-circuit current from distributed generation sources, controlled fault behavior, and the coupling of output characteristics, the fault processes in distribution networks exhibit polymorphic behavior, which may further reduce the accuracy of single-phase fault protection in neutral point ungrounded systems. To address this, a protection method for single-phase grounding faults in distribution networks is proposed, based on the adaptive injection of additional characteristic signals from distributed generation sources. Considering the low voltage ride-through requirements for distributed generation, an adaptive characteristic frequency current injection strategy is introduced. The distribution of characteristic frequency currents in the distribution network is analyzed, focusing on the amplitude and phase characteristics of these currents in the feeders. An active protection method for single-phase faults in distribution networks based on characteristic frequency currents is proposed, and the correctness of this method is validated through simulations.