Capacitor Voltage Ripple Minimization in Voltage Source Converter for HVDC Applications

Abstract

In this paper an exhaustive study on the effects of the circulating currents in the modular multilevel converter in HVDC applications is presented. In the first part, an analytical study of the converter is reported, with emphasis on the capacitors voltage ripple in presence of different circulating currents. In particular, the effects of the second and fourth harmonic components in the circulating current are evaluated in a general working point and, in particular, in the more significant working points corresponding to the inverter, rectifier, inductive and capacitive operation modes. The second part is a simulated HVDC plant verification of the voltage capacitor ripple expression.