Resonant filtering technique to detect symmetric components under unbalanced conditions for control of Active Front End converters

This paper presents a discrete implementation of a complex resonant structure using a mathematical transformation for detection of symmetrical components, for the control of Neutral Point Clamped Three Level Active Front End. The symmetrical positive-negative sequences components of the grid voltage need to be separated to properly orient the control the converter. This prevents oscillations at twice the fundamental frequency on the reference currents on the synchronous reference frame, allowing for current tracking with zero steady state error.