Intelligent Control for Islanded Operation of Doubly Fed Induction Generator based Wind Energy Conversion System coupled to DC Micro-Grid

Abstract

A single parameter based fuzzy model for controlling the Doubly Fed Induction Generator (DFIG) based Wind Energy Conversion System (WECS) to operate in islanded mode is discussed in this paper. The system employs Rotor Side Converter (RSC) and Stator Side Converter (SSC) connected back-to-back to a dc micro grid. The control scheme for both RSC and SSC employ cascaded control loops: Outer speed and inner current loop for RSC and Outer voltage and inner current loop for SSC respectively so as to provide better response during dynamic conditions. In both control schemes, the outer loop is processed and the error along with its derivative is found to produce a single variable for feeding the fuzzy model. As only one variable is involved, less memory occupancy, less complex control and computation is faster. The RSC control employs the speed reference obtained through power calculator based maximum power tracking method which is novel in its kind. The SSC employs the terminal voltage at PCC for the outer voltage loop. The simulation of the system under constant and variable wind speeds is carried out using Simpower Systems toolbox of MATLAB. The results indicate that the efficacious working of the system with faster response to dynamic variations.