Reduced-Order Small-Signal Modeling of PV Storage Systems Considering Dynamic Interactions

The complexity of circuit structures and control loops in three-level interleaved parallel DC-DC converters (TIPDCs) presents significant challenges to the small-signal reduced-order modeling of multi-converter PV storage systems. To address this issue, a research framework featuring “loop/level reduction first, followed by multi-converter equivalence” is proposed. Based on this framework, a reduced-order modeling method considering dynamic interactions is developed. First, the dual-loop three-level DC/DC converter is equivalently reduced to a two-level DC/DC converter model. Moreover, the equivalent analytical equations between the control parameters and filter parameters of the two converters are established. Then, further order reduction is performed on multiple parallel-connected DC/DC converters, and a small-signal reduced-order model of the multi-converter PV storage system is established. Finally, a switching model of the multi-converter PV storage system is implemented on the RT-Box hardware-in-the-loop platform, and the effectiveness of the equivalent reduced-order model is validated by multiple sets of experimental results.