A study on relay coordination in a distribution system with distributed generation and hybrid SFCL

The objective of protective relay coordination in a distribution system is to achieve selectivity without sacrificing sensitivity and fast fault clearance time. When a DG is installed in a distribution system, they change the original steady-state and fault current magnitudes, on which the original relay settings were set. The severity is based on DG´s capacity and its location. Usually disconnection of all DGs from distribution system is the current local distribution company´s practise during fault, in order to maintain the original relay coordination. However, instead of removing DG it is better to limit the fault current from the DG. In this paper hybrid super conducting fault current limiter which gives a promising solution to limit fault current without much loss in electrical energy is considered, modelled and simulated in PSCAD as a countermeasure to limit fault current from DG, in order to improve the disrupted original relay coordination.