One-cycle-controlled (OCC) inverters are suitable for small single-phase photovoltaic distributed-generator systems because of their simplicity

phase-locked-loop free structure

grid voltage sensor-less operation

and cost-effectiveness. Grid voltage sensor-less control helps reduce cost and increases reliability in operation. However various sensors are used for implementation of a protection mechanism. In this paper

a grid voltage sensor-less protection scheme for OCC based single-phase inverter systems is proposed. The estimated value of voltage at point of common coupling (VPCC) is used for protecting the system during over/under voltage conditions of the grid

implementing of voltage ride through conditions

and for disconnecting the grid during islanded conditions. The VPCC is estimated from the measured inverter current

switching pulses

and the measured dc-link voltage using a second-order filter. Simulation and experimental studies are performed to verify the efficacy of the proposed voltage sensor-less protection mechanism triggered using estimated VPCC.