A modified perturb and observe MPPT algorithm with zero steady state oscillation for single-phase grid-connected transformerless solar inverter

This paper proposes a modified perturb and observe (P&O) algorithm to improve the performance of maximum power point tracking in a grid-connected solar inverter. The proposed method eliminates the steady state oscillations in photovoltaic panel voltage under stable irradiance conditions there by enhancing its performance. It also retains the simplicity of conventional P&O algorithm and introduces only one additional step of checking the quantum of power change to bypass the perturbations. A cascaded multi-loop control structure is adopted to achieve the objectives and retain the ability to respond to changing environmental conditions. The proposed and conventional P&O algorithms along with a designed 1 kW single-phase grid-connected transformerless solar inverter are simulated in PSIM to perform a comparative study. Furthermore, the proposed algorithm is validated experimentally on the developed solar inverter prototype.