Robust Regulation of the Photovoltaic Voltage using Sliding Mode Control as Part of a MPPT Algorithm

Abstract

ABSTRACT The cost of the solar photovoltaic energy production is quite high and its efficiency is very low, hence the need to optimize the conversion process. This paper presents the synthesis of a robust control law for regulation of the photovoltaic voltage which is added to a MPPT algorithm to maximize power generated. The simulation results under Simulink confirm the efficiency and robustness of the proposed control. General Terms Photovoltaic systems, Maximum Power Point Tracking, Nonlinear control, Robust control. Keywords Photovoltaic systems, Robust control, Sliding mode control, Photovoltaic power, Perturb and observe MPPT algorithm. 1. INTRODUCTION Photovoltaic solar energy is one of the most dynamic markets of the renewable energy sector. It represents an alternative to traditional methods of producing electrical energy, which emit combustion wastes and pollutants harmful to the ecosystem. Solar energy can be converted into electricity using solar panels which are made of photovoltaic (PV) cells. However, the conversion efficiency is low and the panels manufacturing cost is relatively high. For this reason, the photovoltaic energy conversion must be optimized to the maximum. aThe power characteristic of a panel or PV generator (PVG) is nonlinear. It is characterized by a particular point at which the power supplied by the PVG is maximum. This point is usually noted MPP for Maximum Power Point. The MPPT (Maximum Power Point Tracker) is an electronic device which aims to maintain the system operating point as close to the MPP. In the literature, there are several MPPT control algorithms, the most used is the Perturb and Observe algorithm (P&O). The purpose of this article is the synthesis of a robust and optimal control law for the photovoltaic voltage regulation. It comes to the sliding mode control. This control law is added to the MPPT algorithm to optimize energy conversion minimizing power loss. This paper is organized as follows: the photovoltaic generator is described in Part 2. The matching stage between PVG and a load is presented in Part 3. The MPPT converter together with the P&O MPPT algorithm is outlined in part 4. The synthesis of a robust control for regulating the PV voltage and the simulation results are detailed in Section 5, followed by a conclusion in the last section.