Abstract: Ultra-high voltage DC (UHVDC) transmission systems are among the most promising systems to transmit power for distances up to 3000 km and ultra-voltage up to 2200 KVDC. One of the most challenging issues associated with UHVDC is the conversion of power at the receiving end of UHVDC transmission systems. This paper proposes a pulse-width modulation (PWM) algorithm based on flooring technique for modular multilevel converters (MMCs) to be used with a large scale of submodules per arm that can convert UHVDC 2200 KV and more to UHVAC, reducing total harmonics distortion (THD) for UHVAC less than 1%. A literature review concerns MMC topology and control. Generating insertion indices for number of submodule per arm (N) is derived first. Second, flooring switching PWM is explained to generate number of inserted and bypassed submodules per arm. Third, analysis of the balancing of the submodules voltages and submodules selection, the key technique to achieve insertion and equalization between arm submodules, is proposed and verified by simulation and experiment. Fourth, a set of simulation results for DC bus 2200 KV and 481- level for the output voltage conducted in MATLAB/Simulink environment verify the proposed algorithm. Finally, the prototype’s hardware design and software design verify the proposed PWM algorithm experimentally. This paper shows the experimental results.
Keywords: Modular Multilevel Converter, MMC with Large Number of Submodules.
Title: Power Conversion for UHVDC to UHVAC Based on Using MMC with Large Scale of Output Voltage Level
Author: Abd Almula Gebreel
International Journal of Electrical and Electronics Research
ISSN 2348-6988 (online)
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