Adaptive High Gain Observer for Photovoltaic Systems

The problem of state and parameter estimation in photovoltaic (PV) systems is considered. The system is composed of a photovoltaic generator (PVG) which supplies power, via a long PV cable, to a DC centrifugal pump driven by a DC-DC boost converter. The maximum power point tracking (MPPT) techniques and controllers are generally designed based on the PVG delivered voltage and/or current measurements. From other side, PV arrays should be established in a location that profits from good daily solar radiation. Such a location is, in numerous cases, remote from the converter, which obviously leads to difficulty of PVG voltage and current measurement. Besides, the use of a long PV cable may result in MPPT control inaccuracies due to voltage drops in the cable. For remedying these issues, an adaptive observer for PV systems is proposed, in this work. It accomplishes online estimation of PVG current and voltage as well as of the unknown resistance parameter of the cable. The designed adaptive observer convergence is theoretically proved and its performances are evaluated by simulation.

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