Methodology to Evaluate Converter Structures based on 3L NPC PEBBs

The evolution of self-commutated semiconductor devices, development of fast digital controllers and the emergence of new multilevel converter topologies have allowed to increase the voltage and power ratings of power electronic equipment. This has accelerated the use of these devices in MV levels. As multilevel Voltage-Source Converter (VSC) topology-based equipment prevails in MV applications, the operating range of these converters is getting increasingly wider. A common choice to increase the power rating is to combine basic Power Electronics Building Blocks (PEBB). There is a demand of new operating requirements for power converters, such as unbalances in the grid or fault operation. This paper presents a methodology to evaluate different MV multilevel VSC structures working under any operating scenario. The methodology is integrated into a software-based tool. This tool enables to obtain valuable information to compare, select and design the converter PEBB combination that better suits certain operating requirements. In order to evaluate the potential, the proposed methodology is applied in two operating case studies.