Adjustable variable step-based MRAC MPPT for solar PV system in highly fluctuating and cloudy atmospheric conditions

The most recent scientific concern in solar photovoltaic (PV) energy is to keep PV arrays efficient. The main contribution is to reduce the power loss engendered by variation in atmospheric conditions and load uncertainties. Single MPPT approaches are unable to achieve the trade-off between fast tracking speed and high accuracy. Consequently, a novel adjustable variable step perturb and observe (VS-PO)-based model reference adaptive control (MRAC) for maximum power point tracking (MPPT) application is proposed. Although the speed at which the maximum power point (MPP) is reached, i.e., controlled by the VS-PO algorithm, the accuracy for determining the optimum power is closely correlated with the part of MPP tracking control utilizing the MRAC method. The effectiveness of the proposed VS-MRAC MPPT controller is validated under diverse scenarios such as realistic and cloudy weather, highly fluctuating atmospheric conditions, robustness test, and partial shading conditions (PSC). The realistic weather with or without cloud effects is devised and three case studies are carried out under highly fluctuating atmospheric conditions. Further, robustness test is conducted under random both radiation and temperature with probabilistic load distribution to check the performance of the proposed controller under unexpected system disturbances. The VS-MRAC MPPT exhibits tracking efficacy between 99.26 and 99.70% and reached MPP in just 6.7 ms with negligible loss and ripples, which is 8 and 5 times faster than fixed step PO & VS-PO, respectively. In PSC, four patterns are framed (3 \(\times \) 1 PV string) and it is analyzed that the proposed method tracks global MPP (GMPP) in just 0.05 s with maximum tracked power and negligible shading loss. Finally, the feasibility of the suggested technique is validated in an online mode using real-time simulator (OP4510) in the laboratory.