Wind Power Integration: A Study on Wind Turbines Modelling and Their Impact on Power Systems

Abstract

WIND power is among the world’s fastest growing renewable sources: this may significantly affectpower quality, reliability and stability. This thesis analyzes the performance of three different popular wind generators: the squirrel-cage induction generator (SCIG), the doubly-fed induction generator (DFIG), and the permanent-magnet synchronous generator (PMSG). In order to improve power quality and maintain the stable output generated from SCIG wind farm, this thesis presents also a hybrid controller based on proportional-integral (PI) and fuzzy logic controller (FLC) techniques for adjusting the pitch angle, which is one of the most common methods for smoothing output power fluctuations. Because of relative small rating of the power converters, WT based on DFIG are very sensitive to grid disturbances and require additional protection for the rotor side power electronic converter, such as crowbar protection. In this segment, two layouts of rotor crowbars that have more merits will be compared. To improve the SCIG’s low voltage ride through (LVRT) characteristics, this thesis presents recently developed control strategies for a variablespeed wind power generation DFIG (Doubly-fed Induction Generator) located closely to the SCIG-based wind system by utilizing the control capability of fuzzy logic technique. The proposed control system regulates effectively reactive power output of the DFIG wind turbine by controlling both grid-side and rotor-side converters to compensate the reactive power absorbed by the SCIG-based wind turbine.