A four-step protection strategy to improve stability of high voltage transmission lines.

• The proposed protection strategy enhances the stability and reliability of power systems by. • Precise discrimination between transient and permanent SLG faults. • Fast and precise diagnosis of the successful reclosing time in a case of the transient SLG fault. • Significant reduction in the dead time in a case of the transient SLG fault. • Being efficient even in noise exposure situations and not dependent on the fault location or threshold values. Opportune detection of transient faults and restoration of the faulty phase in the least possible time plays a key role in improving the stability of high voltage transmission lines (HVTLs). This paper presents a novel four-step strategy for the protection of HVTLs so that the stability and reliability of power systems are enhanced. Firstly, the cumulative sum (CUSUM) algorithm is used to quickly detect the transient and determine the faulty phase. In the second step, the settings of the static var compensator (SVC) are changed to reduce the reclosing dead time as much as possible. Afterward, the transient or permanent type of the fault is identified based on the proposed principal component analysis-support vector machine (PCA-SVM) algorithm. In the fourth step, if a transient fault is recognized, the successful single-phase reclosing time is identified by the PCA-SVM and the reclosing command is issued to high voltage circuit breakers (HVCBs). Simulation results obtained by using EMTP-RV and MATLAB for a sample 400 kV power system illustrate that the proposed protection strategy can increase the reliability of the power system via reduction of the dead time, correct detection of transient faults from permanent ones, and accurate detection of the reclosing time. [ABSTRACT FROM AUTHOR]