Frequency Characteristics Analysis of Modular Multilevel Converters with Integrated Battery Energy Storage System

Modular multilevel converter (MMC) and energy storage technologies have been widely applied in the field of flexible DC transmission. With its modular characteristics, MMC can integrate energy storage into sub-modules to form the topology of MMC with integrated battery energy storage system (MMC-BESS). This paper firstly establishes the impedance model of MMC-BESS based on the Harmonic State-Space (HSS) theory. Then, an analysis of the frequency characteristics of MMC-BESS is provided. Subsequently, this paper summarizes three advantages of the energy storage MMC based on its impedance characteristics. Finally, the analyzed conclusions are ultimately confirmed through simulations.