An Efficiency-Based Assessment Study to Allocate Second Life Battery Packs in a Grid-Connected Modular Multilevel Converter

Prolonging the service life of electric vehicle batteries is one of the most prominent challenges of the coming years. After their use in electric vehicles, battery capacity is still more than sufficient for other applications, such as large stationary storage systems aimed at providing grid-support services. This article investigates the usage of second-life batteries (SLBs) in a grid-connected modular multilevel converter, where batteries are integrated directly at the submodule level by exploiting the converter modularity. Based on the SLBs parameters, their allocation in each arm of the converter could lead to different levels of efficiency. Thus, identifying their optimal position inside this power converter is crucial. In this work, different configurations were simulated in MATLAB Simulink™ to evaluate the impact on the overall converter efficiency and provide valuable insights on how it can be maximized through optimal SLBs placement.