The problems in the traditional method of distance relay zone-Ⅱ setting calculation are analyzed

and a novel method is proposed to simplify the setting calculation. As the simplified method is only concerned with the sensitivity requirement without asking for coordination between adjacent lines

the complexity of setting calculation is reduced while the speed of zone-Ⅱ distance relaying is ensured. However

for the possibility of loss of selectivity with the above-mentioned method under some circumstances

a region-based backup relaying scheme is proposed. The startup information of traditional distance relays in local and adjacent substations is utilized to form the logical criterion. The region-based scheme is able to correctly identify the fault location

accelerate the backup relaying

and immunize against the relaying N-1 operation status such as communication failure and element information missing. The results of a case study show that the simplified method of distance relay zone-Ⅱ setting calculation combined with the region-based backup relaying scheme has realized the unification of selectivity

sensitivity and rapidity.