Etude, modélisation et commande d'un micro-réseau multi-sources

Abstract

he main focus of this thesis is to conduct fundamental research regarding control techniques of inverter-based microgrids (MG). It aims to develop new and enhanced control techniques to improve performance and reliability.It emphasises on the modelling, stability analysis and hierarchical control design of parallel inverters in a MG. This thesis presents a general outline of MGs operation modes and control technics, starting by outlining the stand-alone and gridconnected modes besides the transition between them,additional power converters in AC MGs are classified,droop control, and virtual impedance are reviewed.the hierarchical control layers are exhibited,especially the secondary control with their three classifications centralized,distributed,and decentralised. The diagram of the hierarchical control consists of inner,primary,and secondary control levels.The inner control commonly referred as zero level is used to regulate the VSI output voltage.The primary control is based on the droop control method and the virtual impedance loop to share the power accurately regardless of the line impedances.Secondary control is used to regulate the voltage and frequency to their rated values.Also this thesis proposes a fuzzy-based decentralized secondary control for frequency restoration and active power-sharing in an islanded MG.Further,this thesis proposes an improved control technique that maintains stability and shares reactive power equally in isolated MGs