Harmonic State-Space modelling of an HVdc converter

This paper presents a Harmonic State-Space (HSS) model of a fixed delay angle six-pulse High Voltage Direct Current (HVdc) converter. Under the HSS modelling framework, the non-linear switching of the converter thyristors is linearised using a small-signal modelling technique, and described by Frequency Transfer Matrices (FTM). The HSS is an extension to the Harmonic Domain (HD); it captures signal dynamics both in the steady-state and the transient state by the use of the Exponentially Modulated Periodic (EMP) signals. The FTM represents the switching of the thyristors and couple different frequencies around the converter. The modelling results are validated against a time-domain simulation by the PSCAD/EMTDC software package.