Parallel connection of grid-connected LCL inverters for MW-scaled photovoltaic Systems

This paper deals with the parallel connection of photovoltaic inverters in a large scale photovoltaic generation system. 250 kW grid-connected LCL inverters are evaluated in order to achieve parallel operation of two, three, and four units, reaching a total capacity of 1 MW when four units are operating. The concept is to treat these four parallel connected units as one equipment, being able to operate jointly or separately as required. Several operation conditions such as operation at different DC voltage and at different input power are tested. Results show the feasibility of the parallel connection keeping the same characteristics as a single unit, achieving a satisfactory performance for two, three and four parallel connected units.