Impedance Reshaping Strategy for Battery Energy Storage Systems Based on Partial Power Conversion

Abstract

To avoid additional component losses while significantly improving the energy conversion efficiency of battery energy storage systems, the application of series-connected partial power converter (S-PPC) technology in battery energy storage systems is investigated in this study. In the S-PPC battery energy storage system configuration, coupling effects exist between the dc-link side and the battery-series side. The impedance modeling of a battery energy storage system is performed while taking these coupling effects into consideration. To address the instability observed during battery discharge conditions, an impedance reshaping control strategy that is suitable for the S-PPC battery energy storage system is proposed. The proposed method focuses on adjusting the input impedance of the load converter within a limited frequency band centered on the system’s oscillation frequency. This targeted approach significantly improves the stability of the system while ensuring ease of implementation and maintaining high reliability. Finally, the experimental results validate the theoretical analysis.

Keywords

• partial power conversion
• battery energy storage system
• impedance modeling
• stability analysis
• impedance reshaping