Fully extracting fault transient characteristics is crucial for enhancing the protection of renewable power systems. However

existing methods face challenges in setting action thresholds and computational demands. This paper proposes a pilot protection scheme for transmission lines using transient current time-domain mutations. First

the relative time-domain mutation characteristics of fault transient currents in bus outgoing lines are analyzed

leading to a method for determining the fault forward direction without fixed settings. Second

the sequential overlapping derivative transform amplifies high-frequency mutation differences and filters out low-frequency characteristics

simplifying calculations. Based on this

a transient directional pilot protection scheme is proposed. Finally

the scheme's feasibility is verified through PSCAD simulations and hardware tests

showing good applicability and practical engineering value across various transmission lines.