Model Predictive Control Based on Optimized Pulse Patterns for Modular Multilevel Converter STATCOM

This article considers a medium-voltage static synchronous compensator (STATCOM) that is based on a delta-connected modular multilevel converter (MMC) and operates at switching frequencies of 150 Hz or less. Offline computed optimal pulse patterns (OPPs) facilitate the shaping of the grid current spectrum at such low switching frequencies. However, STATCOM applications require the injection of harmonics and negative-sequence currents, as well as fast power transients. In order to achieve this, a model predictive controller is designed, which modifies the switching transitions of the OPPs, inserts additional pulses if required, and controls the circulating current in the delta-connected MMC.