Inrush Identification by Applying Improved Morphological Gradient Algorithm

Inrush current identification is one of the most important aspects in transformer differential protection. However, the traditional methods of inrush identification are not reliable in some particular cases. This paper presents a novel scheme for three phase transformer protection, which effectively identifies inrush currents. In the proposed method, the improved Morphological Gradient Algorithm is employed to extract the features of inrush. Simulation studies have been performed to demonstrate the accuracy and efficiency of the new approach using PSCAD/EMTDC and MATLAB. The proposed method is able to distinguish between an internal fault and inrush, even under CT saturation condition, and its required calculation is simple.