Harmonic Transfer Characteristics of a New HVDC System Based on an Inductive Filtering Method

This paper presents a new HVDC system improved by an inductive filtering method, and afterward proposes a unified equivalent circuit model and a corresponding mathematical model for the calculation of the harmonic transfer characteristics of the new HVDC system. First, according to the special topology of the new HVDC converter station, an equivalent circuit model described by the fundamental and the harmonic impedances is established. Second, via the mathematical modeling of this new HVDC system, a harmonic transfer model is also established, which can be used to express the effect of inductive filtering method on the harmonic distribution characteristics. Moreover, by the theoretical analysis on the commutation process of the HVDC converter, a time-domain expression of the valve current is obtained to represent the harmonic characteristics of the converter. Finally, an experimental study validates the established analytical model and illustrates the harmonic transfer characteristics of the new HVDC system.