An HESS Based on a Modified MMCC-TSBC Converter Integrating Energy Storages

This paper presents a modified modular multilevel cascaded converter based on a triple star bridge cell (MMCC-TSBC) for integrating different types of energy storage to form a hybrid energy storage system (HESS). The proposed HESS comprises battery energy storage, supercapacitor energy storage and a doubly-fed induction machine (DFIM) based variable speed pump storage (VSPS). Different low-rated energy storage units can be intermixed in this converter to form an HESS. This is possible due to the modular structure of the modified converter and provides an advantage in a high-power energy storage system. To validate the performance of HESS, real-time power variation data is accumulated from online sources and a weighted median filter (WMF) is employed for generating appropriate references for battery energy storage system (BESS) and supercapacitor storage to mitigate both low frequency and high-frequency power variations. Here, the control approach permits independent regulation of grid current and DFIM current through the modified MMCC-TSBC converter. The simulation and experimental results validate the effectiveness of the control scheme for the proposed HESS.