Mutilevel Bipolar Back-to-Back HVDC Transmission System Based on the Dual Inverter Converter Structure with Model Predictive Control.

High-Voltage Direct-Current (HVDC) is an attractive solution to conventional ac transmission systems, to transmit bulk electric power over long distances. Multilevel bipolar back-to-back dual inverters convey advantages to HVDC systems, at the cost of increased difficulties to control the AC currents and DC link voltage. This paper presents a control approach for a bipolar HVDC transmission system based on a dual two-level inverter topology with a multilevel structure. For both multilevel inverter AC sides a model predictive control strategy is designed to control active and reactive power, establishing AC grid currents in the sending and receiving ends. The multilevel converter also guarantees the balancing of the DC bus capacitor voltages. To test the performance and effectiveness of this proposed control strategy, several simulation studies are presented and discussed.