Abstract:
The problem of extracting maximum power from a photovoltaic (PV) system with negligible power loss is concerned with the power generating capability of the PV array
and nature of the output load. Changing weather conditions and nonlinear behavior of
PV systems pose a challenge in tracking of varying maximum power point. A robust
nonlinear controller is required to ensure maximum power point tracking (MPPT) by
handling nonlinearities of a system and making it robust against changing environmental
conditions. Sliding mode controller is robust against disturbances, model uncertainties
and parametric variations. It depicts undesirable phenomenon like chattering, inherent
in it causing power and heat losses. In this paper, a robust nonlinear controller based
on supertwisting sliding mode algorithm has been designed which not only removes the
chattering but also enhances the overall system’s dynamic response. Moreover, supertwisting sliding mode controller is robust against changing environmental conditions like change in temperature and irradiance. Noninverting DC-DC Buck-Boost converter has
been used as power conditioning circuit between source and the load. The efficiency of
MPPT of a PV system depends upon the accuracy of reference for peak power voltage,
therefore an efficient mechanism for reference generation has also been proposed in this
work. The reference for peak power voltage has been generated by using a trained arti ficial neural network, which is to be tracked by proposed nonlinear controllers. Sliding
mode controller (SMC) and synergetic controllers have also been designed for MPPT
of a PV system in order to compare them with supertwisting sliding mode controller
(ST-SMC). The Lyapunov based method for stability analysis has been used to ensure
the overall stability of the system. The comparison of ST-SMC has been done with
recently proposed backstepping based controller with integral action and other conventional MPPT controllers given in the literature. The simulation results show the betterperformance of ST-SMC in terms of best dynamic response and robustness.
