A Review of Literature on Effects of Harmonics on Protective Relays

Integration of distributed generations (DGs) and rapid growth of power electronics based loads in the electric power system is infusing harmonics with current and voltage signals. Harmonics are unwanted sinusoidal waves whose frequency is integer multiple of the fundamental frequency. Apart from producing energy losses and harmonic resonance, they also cause malfunctioning and failure of the protection system. The protective relay is a vital part of protection system and its reliable operation is immensely desired. This paper aims at presenting a comprehensive survey on the critical issues of adverse impact caused by harmonics on the performance of various type of protective relays. The software tools that are utilized for the study of relays' performance are briefly mentioned. The possible applications of research done in this field are highlighted as well. A list of standards and papers on the subject are also appended to facilitate researchers and engineers in the field of protection of power system.