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Summary This paper presents a new algorithm for discrimination of short‐circuit faults from power system stressed conditions. The proposed algorithm is based on the combination of distance relay zone‐3 operation and traveling waves generated by either the fault or circuit‐breaker switching. By pick‐up of the distance relay zone‐3, the algorithm looks for traveling waves arriving from the fault point in the first stage. If a fault generated traveling wave is detected, it would be concluded that a fault has occurred. Otherwise, the algorithm enters the next stage and waits for arriving traveling waves caused by open‐switching of the faulted line remote circuit‐breaker. If any traveling wave is detected, the system is under fault condition. Otherwise, the reason of zone‐3 pick‐up is due to a stressed condition. Training a decision tree‐based classifier with the proposed features and simulating the method demonstrate that the proposed algorithm is able to provide a reliable remote back‐up scheme for protection of transmission lines.

Summary A wide‐area backup protection (WABP) method is proposed in this paper based on the zone status of distance relays. The time difference between the operation of zone‐3 and wide‐area based methods makes it possible to employ wide‐area data for improvement of zone‐3. In case of zone‐3 is directly backup for zone‐1, the proposed method can decrease the time delay of zone‐3 with a complete reliability. Moreover, the proposed method is capable of discriminating between the actual faults and power system stressed conditions. Considering the operational time of wide‐area methods, the algorithm could also be applied for zone‐2 backup protection. The proposed method is also developed to consider the availability of wide‐area data for all busses within the disturbance area, as well as data missing for one or two adjacent busses, which are remarkable advantages over the existing WABP methods. Meanwhile, the wide‐area data used in the proposed method are only the pickup/release status of distance relays zones which are binary data and can be communicated readily through existing wide‐area infrastructures. Simulation results on the IEEE 57‐bus test system demonstrate the effectiveness of the proposed method as a promising WABP in improving the performance of zone‐3 in distance protection schemes.