Robust Optimized Pulse Patterns for Converters Connected to a Distorted Grid Via LCL Filters

Abstract

This paper presents robust harmonic-constrained optimized pulse patterns (OPPs) for converters connected to a distorted grid via LCL filters. Specifically, the proposed OPPs ensure compliance with harmonic grid standards even in the presence of unknown harmonic voltages-treated as disturbances-injected to the point of common coupling (PCC) by other converters. This is achieved by formulating and solving a robust OPP optimization problem that accounts for the impact of disturbances while imposing constraints on individual current and voltage harmonics at the PCC. Numerical results demonstrate the grid-friendly operation of the proposed robust OPPs under disturbance harmonics with magnitudes of up to 55% of the maximum levels allowed by grid standards. As shown, the robust OPPs outperform both conventional OPPs and selective harmonic elimination (SHE) in maintaining compliance with harmonic grid standards, despite the disturbances being unknown in the OPP computation process.