Analysis of even harmonics generation in an isolated electric power system

Norikazu Kanao, Yasuhiro Hayashi, Junya Matsuki

Research output: Contribution to journalArticle

2 Citations (Scopus)


Harmonics bred from loads are mainly odd order because the current waveform has half-wave symmetry. Since the even harmonics are negligibly small, those are not generally measured in electric power systems. However, even harmonics were measured at a 500/275/154 kV substation in Hokuriku Electric Power Company after removal of a transmission line fault. The even harmonics caused malfunctions of protective digital relays because the relays used 4 th harmonics at the input filter as automatic supervisory signal. This paper describes the mechanism of generation of the even harmonics by comparing measured waveforms with ATP-EMTP simulation results. As a result of analysis, it is cleared that even harmonics are generated by three causes. The first cause is a magnetizing current of transformers due to flux deviation by DC component of a fault current. The second one is due to harmonic conversion of a synchronous machine which generates even harmonics when direct current component or even harmonic current flow into the machine. The third one is that increase of harmonic impedance due to an isolated power system produces harmonic voltages. The design of the input filter of protective digital relays should consider even harmonics generation in an isolated power system.

Original languageEnglish
Pages (from-to)887-893
Number of pages7
JournalIEEJ Transactions on Power and Energy
Issue number9
Publication statusPublished - 2006


  • DC current
  • EMTP
  • Even harmonics
  • Harmonic impedance
  • Magnetizing current
  • Synchronous machine

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'Analysis of even harmonics generation in an isolated electric power system'. Together they form a unique fingerprint.

  • Cite this