Mission Profile Emulator for MMC-based Battery Energy Storage Systems

Abstract

– In recent years, Modular Multilevel Converters (MMC) have been widely used in medium/high voltage applications, such as high-voltage direct current (HVDC) systems, and pointed out as a promising solution for battery energy storage systems (BESS) and static synchronous compensators (STATCOM), according to recent research. Especially, in BESS application, the current and voltage conditions in the battery bank are fundamental to evaluate thermal dynamic, reliability, and lifetime. However, depending on the voltage and power levels, MMC is based on hundreds of SMs. Thus, the full MMC system implementation can be costly and complex for operational and reliability tests. In this sense, the so-called mission profile emulators (MPE), have been developed to emulate the voltage and current in an SM and batteries. The MPE eliminates the need to implement the full converter and contributes to more agile tests of the MMC dynamics, resulting in the design of more reliable converters. In addition, the MPE can be used to obtain battery current and arm current spectrum similar to those obtained in MMC. This work presents a detailed design and implementation of the MPE for an MMC-based BESS. The MPE is validated in simulations and in a reduced-scale prototype.