Here, a new decentralised approach-based wide-area back-up protection (WABP) scheme is proposed for faulted line identification (FLI). The scheme is divided into two sub-routines, i.e. possible faulted region (PFR) identification and FLI. Initially, the power system under study is divided into different coherent regions. The concept of centre of reactive power (CORP) is used to accomplish the task of PFR. Once the faulted region is identified, FLI is done by continuously monitoring the direction of reactive power flow (DORPF) of each line within the PFR. The proposed scheme is extensively tested on IEEE-39 bus test system for different types of faults. The performance of the scheme under stressed system conditions is also investigated. The obtained results show that the suggested algorithm is able to maintain the balance between dependability and security aspects of the protection logic. © The Institution of Engineering and Technology 2019.