Reconfigurable Control Scheme for a PV Microinverter Working in Both Grid-Connected and Island Modes

• Published in: IEEE transactions on industrial electronics (1982) 2013-04, Vol.60 (4), p.1582-1595
• Main Authors: Trujillo Rodriguez, César, Velasco de la Fuente, David, Garcera, G., Figueres, E., Guacaneme Moreno, Javier A.
• Format: Article
• Language: English
• Subjects: Computer simulation; Control algorithms; Dangerous; Electric potential; Feasibility; Grid-connected mode; Harmonic analysis; Impedance; Inverters; island mode; Islands; microinverter; Pulse width modulation; Reactive power; reconfigurable control scheme; Reconfiguration; Strategy; Studies; Synchronization; Voltage; Voltage control
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2011.2177615

In this paper, a photovoltaic (PV) microinverter capable of operating in both island mode and grid-connected mode by means of a reconfigurable control scheme is proposed. The main advantage of control reconfiguration is that in grid-connected mode, the microinverter works as a current source in phase with the grid voltage, injecting power to the grid. This is the operation mode of most commercial grid-connected PV microinverters. The idea is to provide those microinverters with the additional functionality of working in island mode without changing their control algorithms for grid-connected mode, which were developed and refined over time. It is proposed that in island mode, the microinverter control is reconfigured to work as a voltage source using droop schemes. These schemes consist in implementing P/Q strategies in the inverters, in order to properly share the power delivered to the loads. The aim of the paper is to show that the proposed control reconfiguration is possible without dangerous transients for the microinverter or the loads. Simulation and experimental results on an 180-W PV microinverter are provided to show the feasibility of the proposed control strategy.