Photovoltaic micro-inverter in grid and islanded mode with restructured control adopting second order current algorithm

In this paper, a 180W photovoltaic (PV) micro-inverter which utilizes the same current algorithm for the operation in grid and islanded mode for current shaping is presented. In grid mode the PV micro-inverter acts as a current source injecting power to the grid. The Restructured control with same multi-loop in islanded mode is achieved by implementing P-Q droop scheme avoiding transients, where it acts a voltage source injecting power depending on load requirement. The dc-dc converter is designed to give a 380V dc link voltage. A phase-locked-loop (PLL) for single phase inverters based on a second order generalized integrator is used for grid synchronization independent of grid frequency. Simulation of a grid connected and islanded Micro-inverter with controllers is performed to regulate the system variables.