Hybrid multilevel modular converter for energy storage applications

Multilevel power converters are typically developed for high power applications such as AC drives, energy storage systems, active power filters and compensators. A number of multilevel topologies proposed for these applications. Each topology possesses its own advantages and disadvantages and is used in particular area depending on the system requirement. This paper presents a topology of a hybrid modular multilevel converter developed from a cascaded multilevel topology and parallel NPC converters technique for energy storage applications. The main purpose of the proposed topology is to reduce the DC-link voltage and to preserve acceptable efficiency. Lower DC-link voltage tends to reduction of the battery costs which reaches 60% of the all system's cost. An analysis of the energy quality performance and circulating currents is presented. A case study for 2MW energy storage is studied to provide figures from comparative analysis.