Achieving DC fault tolerance in modular multilevel converters requires the use of a significant number sub-modules which are capable of generating a negative voltage. This results in an increase in the number of IGBT devices in the current path, resulting in an increase in conduction losses within the converter. This paper introduces a thyristor augmented multilevel structure called a Power-Group, offering both negative voltage capability as well as a low conduction loss state, which can be used to construct high efficiency DC fault tolerant converters. When combined with the Alternate Arm Converter topology the power-group concept has been found to result in a converter topology that exhibits very low power-losses, high quality AC and DC current waveforms, while also achieving DC fault tolerance.
|Title of host publication||Cigré HVDC 2016|
|Publication status||Published - 25 Oct 2016|