Harmonic load losses in HVDC converter transformers

Short-circuit losses were measured on a 213 MVA single-phase converter transformer at a number of frequencies between 60 Hz and 6 kHz. Using the results of these tests the harmonic losses during AC/DC converter operation were calculated. Variations of harmonic losses with transformer reactance, transformer winding stray loss factor and converter firing angle were studied. Using exponents of the components of harmonic losses with frequency derived from the tests, a table has been developed for determined the magnitude of the harmonic loss during converter operation. The data required to use the table are derived from design calculations and normal load loss test results