An Advanced Hierarchical Control Strategy for Modeling and Stability Evaluation of a Novel Series-Connected Energy Routing System

This paper proposes an advanced structural modeling and stability evaluation of a novel series-connected energy routing system for residential applications. To address the limitations of conventional converters regarding voltage gain and component stress, the system utilizes a Mirrored SEPIC front-stage integrated with a Dual Active Bridge (DAB) post-stage. This hybrid topology features a high theoretical voltage gain and low hardware complexity. A hierarchical control strategy coordinates photovoltaic (PV) generation, energy storage, direct current (DC) loads, and grid interaction across four distinct energy flow modes. Furthermore, a rigorous small-signal impedance model is derived, and a stability criterion based on the Forbidden Region concept is introduced to guide parameter tuning for the cascaded system. Experimental validation on a 10kW prototype confirms the performance of the system. It achieves a stable 500V DC bus output from an 80V input, corresponding to a voltage conversion ratio of 6.25, while maintaining a low normalized complexity of 1.25 switches per port. During dynamic transitions including 50% load step changes and grid power reversals, the DC bus voltage fluctuation is limited to 3% with a settling time of less than 80ms. The proposed solution provides a scalable, cost-effective, and highly stable platform for residential renewable energy integration.