Power optimization strategy for cascaded DC-DC converter architectures of photovoltaic modules

Abstract

This paper proposes a control strategy aiming at operating cascaded DC-DC converter architectures of photovoltaic (PV) modules at maximum power irrespective of the irradiance conditions, meanwhile meeting constraints of voltage-limitation type. The global optimum of cascaded connections of PV modules is generally equivalent with operating all the modules at maximum power point tracking (MPPT). The most important disturbance occurs when the irradiance levels of modules are sensibly different because of various reasons - in this case, voltage-limitation requirements may be broken. The proposed supervising strategy then attempts to establish the best suboptimal power regime. MATLAB^reg/Simulink^reg numerical simulation results are presented in the case of a monophased grid-connected PV system, where individual MPPTs have been implemented by extremum seeking control (ESC).