Simple scheme to extract maximum power from series connected photovoltaic modules experiencing mismatched operating conditions

Solar photovoltaic (PV) arrays formed by series combination of several PV modules suffer from considerable reduction in power yield when subjected to mismatched operating conditions. To address this issue several schemes have been reported in the literature. Amongst these schemes, the distributed maximum power point tracking (DMPPT) schemes seem to be the most promising ones. However, majority of the existing DMPPT schemes employ voltage-equalisation technique, which cannot attain exact MPP for all the modules. To overcome this problem individual power measurement units are employed for each of the module but then it leads to the involvement of large number of sensors. Schemes which do not require modular level sensing have also been reported but they require to employ a very computational intensive control algorithm coupled with the need for precise communication. This study attempts to address these limitations by proposing a simpler DMPPT strategy. It requires only one conventional MPPT algorithm to extract maximum power from the overall system. The implementation of the scheme is carried out by utilising the power circuit configuration of the existing flyback-converter based standard DMPPT scheme. The viability of the scheme is ascertained through detailed simulation and experimental studies.