Synthesis, Analysis, and Design of a DC-Nanogrid Using Cascaded Converters for Home Applications

The Photovoltaic (PV) plants combined with energy storage systems are one of the promising solutions of full utilization of renewable energies. These main elements can be used to implement a dc nanogrid (dc-NG) which is a power distribution system for a single house/small building, with the ability to connect or disconnect from other power grids. Moreover, the switching dc-dc converters are widely used to interface the dc output of renewable energy resources with power distribution systems in order to facilitate the use of energy at the customer side in a nanogrid. In the case of residential PV applications, the high conversion ratio is usually required, in order to adapt the low output voltages of PV modules to a dc bus voltage, while dealing with the appropriate impedance matching. In this paper, cascaded step-up converters for residential applications are used to step up the PV panel voltage to the dc bus voltage of a dc-NG. This dc-NG is based on conventional control architecture for residential applications. The used controller is based on the voltage and current control using Pulse Width Modulation (PWM) controller. The dc distribution bus is supplied by PV panels, ac utility and a storage battery. The storage battery is connected to the main dc bus through a dc-dc bidirectional converter (BDC). Numerical simulations of a case study corroborate the theoretical predictions of the paper.