Perturbation observer based fractional-order sliding-mode controller for MPPT of grid-connected PV inverters: Design and real-time implementation

Yang, Bo, Yu, Tao, Shu, Hongchun, Zhu, Dena, An, Na, Sang, Yiyan and Jiang, Lin ORCID: 0000-0001-6531-2791 (2018) Perturbation observer based fractional-order sliding-mode controller for MPPT of grid-connected PV inverters: Design and real-time implementation. CONTROL ENGINEERING PRACTICE, 79. pp. 105-125.

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Official URL: http://dx.doi.org/10.1016/j.conengprac.2018.07.007

Abstract

In this paper, a robust/adaptive perturbation observer based fractional-order sliding-mode controller (POFO-SMC) is designed for a photovoltaic (PV) inverter connected to the power grid, in which a maximum power point tracking (MPPT) based on variable step size incremental conductance (INC) technique is achieved to harvest the available maximum solar energy from the PV arrays in the presence of various atmospheric conditions. A nonlinear extended state observer (ESO), called sliding-mode state and perturbation observer (SMSPO), is used to efficiently estimate the aggregated effect of PV inverter nonlinearities and parameter uncertainties, unmodelled dynamics, stochastic fluctuation of atmospheric conditions, and external disturbances. Then, a fractional-order sliding-mode controller (FOSMC) is designed to considerably enhance the system robustness via real-time perturbation compensation and to noticeably accelerate the tracking rate compared to the traditional integer-order sliding-mode control (SMC) through employing a fractional-order proportional–derivative (FOPD) sliding surface. In addition, more reasonable control efforts could be realized since the upper bound of perturbation is replaced by its real-time estimate, such that the inherent over-conservativeness of conventional SMC can be effectively reduced. Four case studies are carried out under Matlab/Simulink environment. Simulation results verify the effectiveness and superiority of POFO-SMC compared to that of proportional–integral (PI) control, feedback linearization control (FLC), SMC, robust SMC (RSMC), and FOSMC. Finally, a dSpace based hardware-in-loop (HIL) experiment is undertaken for the purpose of implementation feasibility validation.

Item Type:	Article
Uncontrolled Keywords:	Solar energy, Grid-connected PV inverter, MPPT, Nonlinear perturbation observer, Fractional-order sliding-mode control, HIL experiment
Depositing User:	Symplectic Admin
Date Deposited:	14 Nov 2018 08:39
Last Modified:	26 May 2023 21:11
DOI:	10.1016/j.conengprac.2018.07.007
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3028791