OPTIMIZED PULSE PATTERNS FOR MMC CONTROL

摘要

The present invention is concerned with improving spectral and dynamic performance and scalability of controlling a Modular Multilevel Converter (MMC). According to the invention, a converter flux control is proposed that includes virtual converter flux tracking for a grid-connected MMC based on Optimized Pulse Patterns (OPP). The proposed flux control enables all required STATCOM tasks, including i) injection of harmonic currents and ii) unbalanced operation of the STATCOM for negative sequence current injection and operation under grid imbalances. A per-device switching frequency and switching losses are significantly decreased compared to a PWM-based control for a similar spectrum shape during nominal operation, while all spectral requirements on the output current are met. The proposed converter flux control may preferably include a Model Predictive Pulse Pattern Controller (MP3C).