Defining Interharmonics

Read the importance of understanding harmonic and interharmonic groups and subgroups for PQ analysis.

Interharmonics are frequency components at non-integer harmonics of the line frequency. The proliferation of large DC-converter variable speed drives and wind/solar inverter generation has led to an increase in interharmonic levels.

Troubleshooting the resulting problems requires measurements and terminology that go beyond “simple” harmonics. This whitepaper covers the definitions and meaning behind the terminology for interharmonics, as defined by the IEC 61000- 4-7 standard.