Parameter Balancing Control (PBC) for Series PV Arrays

• Main Authors: Yi Cheng Liu, 劉宜誠
• Other Authors: W. L. Chen
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/29000108062051520309

碩士 === 長庚大學 === 電機工程學系 === 101 === A photovoltaic (PV) array is composed of a number of series-connected PV modules. If one of the PV modules suffers from partial shading or aging effect, the current of PV string would subject to the derated module and consequently deteriorate the overall power efficiency. The parameter unbalance among the PV modules also results in a power-voltage curve that exhibits multiple local maximum power points (MPPs). Although many algorithms declare the solution achieving global optimization, the random variation in solar irradiation would give rise to unsatisfactory efficiency when the algorithm is on the run searching for the global MPP. To balance the parameter among the PV modules, a simple buck converter is configured at the terminal of each PV module in order to alter the output current-voltage (I-V) characteristic. With the help of the buck converter, the parameter of the PV modules becomes consistent and can be strung together without losing energy from parameter mismatch conditions. A maximum voltage point tracking (MVPT) algorithm is proposed for the buck converter to achieve the local MPP when the output current of the buck converter associated to the PV module in shadow is consistent with other PV modules. To attain the global MPP for the PV array, a boost converter is employed to condition the output current of the PV array. A perturbation and observation (P&;O) algorithm is used to search the optimal output current of the PV array corresponding to the global MPP. The experimental results confirm the effectiveness of the proposed strategy.