Development and Testing of Protection Concepts for Modular Multilevel Converters using Back-to-Back Operation

Abstract:
This paper focus on protection design and testing of single cells for modular multilevel converters. High power platform is being built for experimental verification of cells and further topologies design. Initially current controlled full-bridge (FB) cells are used in back-to-back topology in order to reproduce realistic electrical and thermal operating points. Cell design is explained as well as its control structure and protection scheme. Simulation results for normal operation and selected fault modes are presented and analysed in order to verify the effectiveness of the proposed protection concept and to elaborate the testing steps required for validation.