Fault Protection Device Design and Protection Strategy for D-UPFC

In order to prevent the damage to the low voltage side of the unified power flow controller (D-UPFC) facing the distribution network when the over-voltage and over-current faults occur in the system, the parallel fault protection device with fast bypass has become an indispensable part of the system design. In this paper, a fault protection device suitable for D-UPFC is designed, including thyristor bypass switch (TBS) and TBS controller, and a three-level protection strategy is proposed. When the high- voltage primary side system fails, the D-UPFC converter can be bypassed quickly to achieve rapid escape and protection of the main equipment.