Optimal Management Strategy for EV Fast Charging Infrastructure With Multiple Interlinking Transformers

This article proposes a multiobjective optimization framework designed to maximize electric vehicle (EV) charging profit while providing power-factor correction (PFC) in a DC-coupled charging-station (CS) infrastructure supplied by a low-voltage grid, considering multiple local transformers. The optimization layer is embedded into a power-sharing control strategy based on piecewise functions, which manage the energy flow among second-life batteries (SLBs), EV batteries, and grid-connected inverters (GCIs). The proposed control architecture allows flexible modification of optimization constraints without compromising system stability, thereby preventing accelerated transformer loss of life and enhancing adaptability and scalability in power distribution under industrial-load variations, low-voltage ride-through (LVRT) events, communication faults, and standalone operation. Hardware-in-the-loop results demonstrate that the optimization increases overall profits for CS owners by up to 15% while providing PFC above 0.85 for industrial power systems. Moreover, the adaptability of the solution prevents overloads in SLBs, GCIs, and transformers by limiting their power operation to a maximum of 1 p.u., while the LVRT support protects the grid network against undervoltages below 0.9 p.u.