Control Strategies for Modular Grid-tied DMPPT Systems Integrating Photovoltaic Generation and Battery Storage at Module Level

This paper presents new control strategies for PV and battery integrated Distributed maximum power point tracking (DMPPT) systems. The presented system shows increased performance under large mismatching conditions thanks to the adopted strategies: (i) an adaptive DC-bus voltage extends the MPPT operating range of the converters dedicated to control single photovoltaic panels and (ii) the integration of batteries at module-level further compensates the output voltage level of the converters. A novel output voltage estimation is presented as well, providing full control of the converters' output voltages with reduced sensing circuitry. In addition, a sequential control that coordinates PV voltages and the DC-bus voltage is addressed, as a first step to suitably couple the distributed and the central tracking functions of the system.