Performance analysis of grid tied novel Transformer less Inverter topology for Photovoltaic Systems with cascaded controller

Photovoltaic (PV) systems are widely used for clean energy generation, with transformerless inverters commonly connecting PVs to the grid. However, most existing works have disadvantages like high leakage current and harmonics. This paper introduces a novel 11-level transformer-less multi-level inverter topology for PV systems, designed with fewer switches and a single DC source to mitigate issues of high leakage current and harmonics prevalent in existing inverters. To optimize performance, the paper proposes an Osprey Optimization Algorithm (OOA) tuned cascaded fractional order proportional integral proportional derivative (CFOPI-PD) controller for the inverter, alongside a perturb and observe (P&O) based maximum power point tracking (MPPT) for the PV array. Simulation results in MATLAB/SIMULINK demonstrate the effectiveness of the proposed methodology, achieving a reduced leakage current of 0.05A, a converter efficiency of 98.40%, and a low total harmonic distortion (THD) of 0.71%, outperforming existing topologies. The proposed model has obtained current THD values of 0.71% for both simulated and measured results. In the proposed topology, the switch count is reduced to seven with a single DC source and achieves lower THD and higher efficiency compared to previous 11-level inverter designs.