Application of out-of-step relaying systems with wavelet transform on the KEPCO 765 kV power system

Sudden change occurring in the loading configuration of electrical power networks may result in power swings at power system. In order to prevent the distance protection from mal-tripping during such conditions, a power swing blocking device is often utilized. However such devices cannot cope with very fast power swings faults and high impedance resistance earth fault. In this paper, a new scheme is presented using wavelet transform algorithm for fault during power swings in power system. Several families of wavelets are used to analyze transient fault signals in a 345 kV model system generated by EMTP. The process was performed at a real power system [765 kV transmission system in Korea Electric Power Corporation (KEPCO)]. It was verified to improve a stable operation of the power system by classifying power swings and various kinds of faults clearly.