A novel unit protective relaying concept based on current signal sequential overlapping derivative transform: Two sides fed transmission line application

This paper presents a novel and accurate unit protective relaying concept for EHV transmission lines. The proposed protective concept implements a simple current signal sequential over lapping derivative, SOD transform to detect transmission line transient disturbances. It uses both polarity and magnitude of the first disturbance, arrived at relay location, to identify internal and external faults rapidly. The proposed unit protective relaying concept is applied to two sides fed transmission lines. The simulation results presented show that the protective concept is simple with high reliability, sensitivity and achieve an extra high speed relaying. In addition, it has immunity against the influence of the large capacitance of the line, the saturation of the current transformers and the synchronization problems.