Maximum power point tracking control of a high power dc-dc converter for PV integration in MVDC distribution grids

This paper discusses the design of a control strategy for a three-phase dual-active bridge (DAB3) dc-dc converter, which is employed as the central converter to track the maximum power point (MPP) of a large-scale photovoltaic (PV) farm, and to deliver the generated energy into dc distribution grids. Considering the soft-switching characteristics of the DAB3 converter, two different maximum output power point tracking strategies are proposed to maximize PV power generation. To achieve a fast transient performance of the maximum-power-point-tracking (MPPT) based voltage control especially considering the non-linear characteristic of the PV panels, the PV current is compensated with a feedforward function in the cascaded control loop. A down-scaled laboratory prototype of the DAB3 converter is designed and tested with PV panels to validate the performance of the proposed control method.