Optimized thermal management system of Modular Multilevel Converter for HVDC applications

The dynamical behavior of temperature is becoming a critical design consideration for the Modular Multilevel Converter (MMC). Investigation of an advanced control structure for Grid Connected-Modular Multilevel Converter (GC-MMC) is proposed in this paper. To achieve this goal, an non-linear model of MMC regarding considering of negative and positive sequence components with thermal dynamics has been presented. Then, due to existence of unbalance voltage faults in distribution grid, non-linarites and uncertainties in model, adaptive robust current controller which is composed of sliding mode and fuzzy control, is developed for GC-MMC. They are implemented based upon positive and negative components of voltage and current to mitigate the power quality problems. Finally, numerical results are given in order to show the dynamic performance of GC-MMC prototype under normal and unbalanced fault conditions. They illustrate the proposed current controllers could keep the MMC stable under different conditions and thermal performance of MMC is given.