A Cascaded Multilevel Modular Energy Router Hybrid Photovoltaic and Energy Storage With Improved Power Balance Capability

Cascaded H-bridge (CHB) converter has become an attractive topology for future large-scale photovoltaic (PV) plants in medium-voltage microgrids. However, the unequal irradiation and aging degree of PV arrays will lead to imbalanced and inconsistent output power between the three phases. This paper presents a novel approach to integrating PV and energy storage (ES) systems inherent in microgrids, utilizing a hybrid CHB-based energy router (HCHB-ER), which is configured with a limited number of sub-modules to connect with the centralized ES. The proposed topology can handle serious inter-phase power imbalance and respond to grid-side power scheduling, without the appearance of over-modulation and common-mode voltage rise caused by traditional zero-sequence voltage injection methods. Under the three major constraints from the modulation level, the CES maximum intra-power regulation boundary and sub-module configuration ratio are analyzed in detail. Additionally, the power imbalance regulation capability of the proposed HCHB-ER across various configurations ratios is thoroughly evaluated, and compared with the zero-sequence injection methods. Finally, the correctness and effectiveness of the proposed strategy are verified by simulations and experiments.