| This thesis investigates the control and operation of an HVDC hybrid topology utilizing a line commutated converter (LCC) rectifier and a multi-terminal connection of modular multilevel converter (MMC) inverters. The hybrid LCC-MMC system leverage the features of both LCC and MMC technologies. The LCC is more economical, mature, and has a higher power capacity, while the MMC has a smaller footprint, reactive power control, no risk of commutation failure and can connect to weak AC systems.;This thesis has four main objectives: (1) development of HVDC characteristic control curves for the proposed hybrid LCC-MMC system which describe operation under normal, DC fault, and AC three-phase-to-ground fault conditions, (2) manage current sharing amongst a multi-terminal connection of inverters, (3) define controls for FB-MMC operation, and (4) demonstrate operation of the proposed system through PSCAD/EMTDC simulations. The hybrid LCC-MMC topology represents a viable candidate to integrate remote energy sources to congested weak AC systems. |
