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Distributed Power Flow Controller (DPFC) is a typical D-FACTS device for power flow control by distributed installation, which is installed on overhead transmission lines or substations. The voltage source converter (VSC) unit in DPFC is connected in series to the transmission line, which can adjust the line impedance continuously and quickly. DPFC obtains energy mainly through the AC line current. When the line current is too low, DPFC cannot obtain energy reliably. In this paper, the control strategy of DPFC under low AC line current condition is proposed to prevent the DPFC from losing control under low current condition to protect DPFC equipment. The rationality and engineering applicability of the proposed strategy are verified by experimental results of Hu Zhou DPFC project.

Harnessing natural water currents for renewable energy generation holds significant promise. Flapping foil hydrokinetic turbines (FHTs), inspired by aquatic organisms' propulsion mechanisms, leverage undulating motion to extract energy from flowing water. This study investigates the impact of hydrofoil shape and mechanical parameters on oscillating tandem hydrofoil systems' performance for energy harvesting, focusing on Persian Gulf tidal currents. Computational Fluid Dynamics (CFD) in a 2D domain is employed for analysis. Parameters include hydrofoil profiles (IFS, NACA 0015, HSVA, and flat plate), damping coefficient, and initial pitch angle optimized for low-level currents around 1 m/s, derived from HYCOM data. Numerical simulations highlight the superior hydrodynamic efficiency of the IFS hydrofoil. Through RANS equations in unsteady conditions, an optimal configuration with a 75-degree initial angle and damping coefficient of 4 achieves a maximum power efficiency of approximately 66.77%. Efforts have been made to ensure data accuracy, including rounding reported efficiencies appropriately and conducting thorough uncertainty analyses. • An effective hydrofoil profile, such as the IFS, enhances the efficiency of energy extraction. • The damping coefficient, set at 4, showcases optimal performance. • Tandem Flapping Hydrofoils exhibit efficiency in low-level currents. • The system's optimal performance is demonstrated by the 75-degree initial pitch angle. [ABSTRACT FROM AUTHOR]