CSMC-SPWM modular multilevel converter for HVDC transmission system

This paper presents a control process and the functioning of Modular Multilevel Converter (MMC) in high-voltage DC transmission system. A new algorithm is proposed to generate gate pulses of the switching devices for running, shifting the system from higher to any other lower level or any other lower level to higher level of operation, which is based on Carrier and Signal (reference) Magnitude Control Pulse Width Modulation (CSMC-SPWM). Moreover, this control method generates pulses for the faulty Sub-Modules (SM) to bypass the supply voltage to un-faulty SMs. The simulation results show that MMC operates well to any level of operation and faulty SMs are completely removed from any phase of the inverter.