Current collector optimizer topology to extract maximum power from non-uniform aged PV array

摘要

Centralized inverter technology is one of the most common architectures of the PV installation, which interfaces a large number of PV panels that configured in series-parallel (SP) combination to the grid. However, the power generated from centralized inverter architecture based on SP array topology is significantly reduced under the non-uniform aging condition. Non-uniform aging of PV panels is a common problem in the PV generation plants, as they often operate under harsh outdoor environmental conditions for a long service period. Due to the elevated price of replacing aged PV panels with new ones, it is preferable to improve the power extracted from aged PV systems. This paper proposes a circuit-based topology known as current collector optimizer (CCO) topology to enhance the performance of centralized inverter technology under the uneven aging condition of PV modules. According to the results, the maximum power extracted from the non-uniform aging PV array is substantially increased by using the CCO topology compared to the conventional SP array topology with bypass diodes. With CCOs, the PV array characteristics have a unique maximum power point (MPP) which can be easily followed by a simple MPP tracking algorithm, subsequently, the CCO topology does not suffer from misleading power losses. The proposed topology requires offline rearrangement of aged modules to obtain the optimum power if only the degradation rate of short-circuit current is used to assess the aging process. Furthermore, the CCO topology operates close to optimum power if the degradation rate of open-circuit voltage is taken into account.