Modeling and control of single-stage grid-connected PV systems with extremum-seeking based MPPt

  • Ammar Elnosh

Student thesis: Master's Thesis

Abstract

Solar energy is one of the major renewable energy sources that have a high potential for utilization in power generation, especially in the MENA region and the UAE. As the efficiency of Photovoltaic (PV) cells is relatively low, it is important to extract the maximum amount of available power through efficient power electronic interfaces. This thesis studies single-stage three-phase grid-connected PV systems with a focus on developing an efficient power electronic control based on Maximum Power Point Tracking (MPPT). A complete simulation model is developed via MATLAB/Simulink for the PV array, the grid-interface, and the inverter control as a platform to implement different MPPT techniques. This study primarily focuses on the problem of partial shading of PV arrays which is a very common issue especially in urban areas. Since partially shaded PV arrays exhibit a multi-modal behavior on their Power-Voltage characteristics, the MPPT under such conditions becomes a complex task. Moreover, the high level of uncertainty and huge number of possible patterns makes the MPPT even more difficult. An Extremum-Seeking Control (ESC) based method is proposed in this thesis to track the global power peak under non-uniform irradiance conditions. It relies on measurements of power and the estimation of the power gradient to determine the segment of the Power-Voltage characteristics in which the global peak lies, without the need to converge at the other local maxima. The proposed method was compared to the sequential ESC-based MPPT method presented in the literature. Different test scenarios of partial shading show that the proposed method can reach the global peak with a faster convergence rate than the sequential ESC method.
Date of Award2012
Original languageAmerican English
SupervisorVinod Khadkikar (Supervisor)

Keywords

  • Modeling-Anatomic
  • Modeling-Technique

Cite this

'