PV-BESS DC-Series Integration for Regulated DC Systems

DC-series integration introduces a novel approach to seamlessly integrate a solar photovoltaic (PV) array and a battery energy storage (BES) in series. This system, referred to as the PVintegrated battery energy storage system – DC series (PVBESSDCS), simplifies integration and enhances power density by leveraging the inherent voltage-source characteristics of batteries and adopting the concept of partial power processing. However, addressing voltage variations of a PV array and a BES under different operational conditions remains a challenge to apply the PVBESS-DCS to a regulated DC system, where the DC bus voltage is fixed. This paper proposes a PVBESS-DCS solution tailored for regulated DC systems. Within this framework, we present a controllable series voltage source compensating for the voltage differences between the PV and BES sources and the DC bus. Thus, the system can perform PV maximum power point tracking and curtailment control while charging and discharging BES and connected to a regulated DC bus. Additionally, we present a single-stage multi-port partial power processing DC-DC converter designed for the proposed PVBESS-DCS. It utilizes a triple active bridge DC-DC converter topology. This paper presents operating principles, control strategies, simulation results, and experimental findings of the proposed PVBESS-DCS for regulated DC systems.