Performance evaluation of grid-connected power conversion systems integrated with real-time battery monitoring in a battery energy storage system

Abstract

This paper aims at investigating power conversion system (PCS) and lithium-ion (Li-ion) cells employed in a grid-connected battery energy storage system (BESS). For PCS, the work evaluates the efficiency performance among the four topologies commonly used in power grid using PSIM. The output power, DC link voltage, semiconductor devices’ configurations and pulse width modulation method are the four parameters which are set constant in order to obtain a fair comparison among the topologies. From the simulations, it was observed that direct DC–AC inverters (98.3–99.1%) yield better efficiency performance compared to conventional DC–AC inverters (98.1–99.0%). Besides, a Li-ion cell is monitored during its charge and discharge cycles where state of charge is estimated via the combination of Coulomb counting and open-circuit voltage method. State of health is predicted by measuring the battery capacity in an experimental setup which aims to predict battery remaining useful life, hence improving the reliability of a BESS.