A Novel Modular Multilevel Converter-Based Hybrid Photovoltaic and Battery Storage System

The large-scale development of photovoltaic (PV) requires the PV grid-connected system to have the ability to actively support the grid. The existing PV converter topology has problems of small capacity and weak transient support ability. This article proposes a novel converter topology (HMMC) that integrates PV and battery into the submodules of modular multilevel converter, which can effectively enhance the capacity of a single converter. Based on the analysis of the capacitor energy and energy storage energy inside HMMC, a grid-forming (GFM) control strategy for HMMC was designed, which can achieve self-synchronous operation and support grid frequency and voltage. The effectiveness of the proposed topology and control strategy was verified through simulation results.