Analysis of the Doubly Fed Induction Generator performance on frequency support of microgrids

Abstract

Doubly Fed Induction Generators (DFIG), represent one the of the most employed technologies, for wind conversion systems. Due to the intermittent nature of wind, the conventional control used by these generators has the objective to operate at a point that ensures maximum power extraction of the wind turbine. However, using only this control philosophy, these generators do not participate in frequency control of the power system, since the mechanical system is decoupled from the electrical system due to the action of the back-to-back converter. Consequently, the conventional DFIG does not present inertia response. However, in power systems with high penetration of wind power generation, or systems that operate islanded, as microgrids, the wind power generator inertia response allows a smother behavior of the electrical frequency. In this context, this work studies, analyzes and compares the Doubly Fed Induction Generator behavior contributing to the frequency support of a microgrid formed due an unintentional islanding through the implementation of three control methods in the rotor side converter of the DFIG. In order to evaluate this behavior, computer simulations were performed simulating the occurrence of islanding, where a part of the distribution network shall operate islanded with power supplied by a DFIG and by a synchronous generator. The results allows analyzing the performance of DFIG in the grid frequency support considering different methodologies.