1Perez L G, Urdaneta A J. Optimal Coordination of Directional Over-current Relays Considering Definite Time Backup Relays.IEEE Trans on Power Delivery, 1999, 14(4): 1276-1284.
2Perez L G, Urdaneta A J. Optimal Computation of Distance Relays Second Zone Timing in a Mixed Protection Scheme with Directional Over-current Relays. IEEE Trans on Power Delivery, 2001, 16(3): 385-388.