Sequential model predictive control for five-level MMC-based multi-terminal HVDC systems

In this paper, a Sequential Model Predictive Control (SMPC) is proposed for controlling a Modular Multilevel Converter (MMC)-based Multi-Terminal high Voltage Direct Current (MTDC) grid. Based on an adequate predictive model of the grid side of each MMC unit, cost functions are designed and optimized to generate the appropriate switching states of each MMC. In addition to its ability to guarantee accurate power-sharing between deferent controlled MMCs units, the conspicuous features of the propose MPC strategy are the sub-module capacitor voltages balancing and MMC circulating currents minimization. To validate the performance and the effectiveness of the proposed control approach in terms of its ability to achieve the desired performance under various operational conditions, comprehensive simulation studies are conducted on a four-terminal MMC-MTDC system.