부산대학교 도서관

Photovoltaic (PV) systems are one of the key solutions to face the increasing energy demand and climate change. PV elements are commonly connected in series to obtain the required voltage. PV strings suffer from severe power reduction when a mismatch occurs. A mismatch can occur because of partial shading, uneven dust, unequal tilt angles, or degraded modules. Differential Power Processing (DPP) is used in PV systems to minimize energy conversion losses while optimizing the PV power during mismatch. One way to implement DPP is using the PV-bus DPP architecture, where each DPP converter is connected between a PV element and the collective bus. The total processed power in the PV-bus system depends on the substring current. Analytically, the substring current has a unique operating point to achieve the least processed power (LPP) through all DPP converters. This article presents a new method to control the substring current for achieving LPP in the PV-bus system. The proposed control method does not require an extra string converter and is based on controlling the existing DPP converters with a single-stage inverter. Different mismatch levels are analyzed to show that the proposed system can reach LPP, significantly reducing the total processed power. Simulation and experimental results were performed to validate the effectiveness of the proposed method.