Fast Identification of Symmetrical or Asymmetrical Faults During Power Swings with Dual Use Line Relays

Increasing power demand, penetration of renewables, and limitations of necessary grid expansion are proffering new challenges to existing power system protection and control strategies. However, with the advancement in intelligent electronic devices and relaying technology, fast, accurate and reliable protection schemes can be developed for smart power systems. In this paper, a new protection scheme based on admittance and power change has been proposed with dual-use line relays to detect symmetrical/asymmetrical faults in power systems. A large number of fault environments have been simulated by varying fault distances from relay location, fault resistance, and power angle in single machine infinite bus and WSCC 9-bus systems. Some crucial decisive fault scenarios e.g. close in/far end faults, faults in series compensated line, faults during asymmetrical swings, switching ON/OFF large loads, single and multi-modal swings have also been verified for the proposed index. In this paper, for the first time, detection of faults during power swings have been examined and verified in the presence of wind farms. The simulation results show the proficiency of the proposed algorithm for detecting faults in the presence or absence of power swings.