Some ground fault protection schemes implemented on FTU for industrial power systems

Many industrial power systems have been operated with floating neutral or high resistance grounding. With traditional fault detection methods, based on zero sequence current, it is difficult to satisfy the requirement of distribution automation (DA). In order to improve this, some novel techniques for ground fault feeder detection are presented in this paper, and they are implemented by using the information obtained from the feeder terminal unit (FTU). The faulty feeder is identified with fuzzy analysis. These protection schemes have been verified by EMTP simulation. A prototype has been developed and tested in a dynamic power system. Results show that these proposed protection schemes have high sensitivity and robustness to detect all kinds of ground faults.