110kV Line Distance Protection for Distributed Power Access Systems Adapted to Switchover from Standby Devices

For distributed new energy power supply access systems that include the switch over of the standby device, the traditional protection scheme has a series of adaptability problems due to the complex fault characteristics of the new energy source and the change in system structure brought about by the switchover of the standby device. For this reason, a line protection scheme is proposed that uses a fast distance protection algorithm with equal transmission in the case of a line unprotected near-zone fault, and a fault direction discriminating relay based on the correlation coefficient of the voltage drop waveform in the case of a line protected near-zone fault. The scheme can adapt to the access of distributed new energy sources and is suitable for both scenarios where the working power source is operating normally and where the working power source is disconnected and the backup power source is put in. Simulation analysis demonstrates the applicability of the scheme.