A directional protection scheme based on non-periodic current for transmission lines

This paper presents a directional protection scheme for transmission lines based on directional comparison of the non-period current, which is estimated by a second-order differential algorithm. When the directions of non-periodic current at both sides are the same, the fault is discriminated as internal fault. When the directions are opposite, the fault is discriminated as external fault. A variety of fault scenarios has been simulated on a 500 kV transmission line using MATLAB, and the results have demonstrated that the proposed method can discriminate the internal fault and external fault accurately.