Analysis of Distance Relay Performance in the Presence of DFIG-based Wind Integration

Hz. Single-line-to-ground (SLG) faults are applied at remote-end locations corresponding to 90% of line length, representing the most prevalent fault scenario in the transmission network.

A sequential generator replacement framework is adopted to ensure that the influence of each

DFIG integration scenario can be independently evaluated without altering network topology or protection coordination. In order to isolate the effect of generation replacement, distance relay settings remain unchanged throughout. The DFIG output power is varied from 10% to 100% rated capacity in a systematic manner to emulate realistic wind speed variations and converter operating conditions. Relay tripping times and operational reliability are analysed for several electrically proximate relays to the replaced generator. The results show significant deterioration in distance relay performance due to DFIG integration under SLG faults. Tripping-time delays and instances of relay non-operation are observed as DFIG penetration is reduced, indicating under-reach and loss of dependability, while higher penetration levels lead to unintended relay operation, reflecting over-reach and protection mis-coordination. It is also demonstrated that the severity of protection degradation depends on both the location of the replaced generator and the level of DFIG generation. These findings provide quantitative insight into the evolving protection challenges of converterdominated transmission systems. Results confirm that conventional distance protection schemes are less dependable in a DFIG-dominated network and call for revised or adaptive protection strategies in renewable-rich transmission systems.