Novel pilot protection for transmission lines with large-scale wind farms based on trajectory distance characteristics.

• A new method is introduced to improve the one way distance (OWD) algorithm. • An improved OWD algorithm is used to identify internal and external faults. • The ratio of nonsimultaneous points is proposed to enhance the protection security. • To reduce the impact of CT saturation, the virtual clamped current is proposed. • The results show that the performance of the proposed protection is satisfactory. In terms of integrating large-scale wind farms into power systems, the fault characteristics of power systems have undergone fundamental changes, potentially leading to the rejection and misoperation of traditional protections. To address these issues, a time-domain pilot protection based on trajectory distance characteristics is proposed. A novel trajectory distance calculation method is introduced to improve the one-way distance (OWD) algorithm, which is used as a metric to quantify the distance between current trajectories to identify internal and external faults. To overcome the adverse impact of nonideal conditions, a metric, namely the ratio of nonsimultaneous points is proposed. Faults are identified using two metrics. Validation results from PSCAD/EMTDC and hardware-in-the-loop platform demonstrate that the proposed protection can operate within 15 ms in most cases and has excellent robustness against diverse nonideal conditions, including tolerating noise with 10 dB signal-to-noise ratio. Moreover, it considerably outperforms traditional and new differential protection methods. [ABSTRACT FROM AUTHOR]