Conversion architectures for combined photovoltaic storage systems: Modeling and efficiency analysis

In order to increase the integration of photovoltaic generation into the electricity grid, photovoltaic systems may be combined with electrical energy storage system (ESS). Such combination increases the controllability of the resulting PV-storage plant. Different conversion architectures may be used for the combined PV-storage system. The objective of this paper is to compare the efficiency of different conversion architectures when used for a particular application and for a selectable period of time. For this purpose, a flexible simulation tool, that allows analyzing different case studies, has been built. In the simulation tool the power converters are modeled through efficiency tables that are calculated from a detailed model of the power converter. The converter model includes commutation and conduction losses of IGBT modules, and filters and transformers losses. DC models of the PV system, as well as of the storage system, are also integrated. The analysis is based on simulations of the operation of the PV combined with the storage system for a one year period and a half hour time step.