Analysis of harmonic transfer through an MVDC link

The impact of harmonics and resonances on the medium voltage direct current (MVDC) link embedded in the Anglesey 33 kV distribution networks is evaluated in this paper. The background harmonics at either end of the MVDC link is analysed to identify dominant harmonic components. The ac to dc conversion is evaluated with focus on the dc link topology and its harmonic behaviour. This is followed with a detailed power electronic converter switching model implementation for harmonic transfer studies. The modelling aspects resemble the proposed Angle DC converters as close as reasonably practicable. To align with this objective cascaded three level Neutral Point Clamped (NPC)-based MVDC link has been implemented in the PSCAD/EMTDC simulation platform. The MVDC link is in symmetrical monopole configuration capable of operating at bipolar voltages, resembling the Angle DC link operation. Furthermore, the analysis focused on the different dc link configuration and their behaviour to ac system background harmonics. The results show potential harmonic transfer through the MVDC link.