Enhancement of extracted maximum power from partially shaded multi-string PV panels using a new cascaded high step-up DC-DC-AC converter

Partially shaded problem in multi-string PV panels is a major challenge because it reduces the value of generated power from PV panel. In this paper, a new cascaded high step-up DC-DC-AC converter based on SEPIC converter is proposed for partially shaded multi-string PV panels. To solve the challenge of partially shaded in PV system, a SEPIC dc-dc converter is connected for each string and the duty cycle of the each SEPIC converter is controlled to extract maximum power from each string using Perturb and Observe (P&O) algorithm. It increases the total extracted power from PV panel substantially. The proposed DC-AC converter can generate a large number of levels at output to reduce total harmonic distortion. This converter uses the least number of components such as IGBTs, drivers, capacitors and anti-parallel diodes which is an important advantage. Simulation results based on PSCAD/EMTDC software are verified the operation of presented structure.