Advanced simulation of windmills in the electric power supply

An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which ma kes it possible to investigate dynamic behaviour of grid-connected windmill s as a part of realistic electrical grid models. This means an arbitrary nu mber of wind farms or single windmills within an arbitrary network configur ation. The windmill model may be applied to the study of electric power sys tem stability and of power quality as well. It is found that a grid-connect ed windmill operates as a low-pass filter, whereby the two following observ ations are made: (1) interaction between the electrical grid and the mechan ical systems of grid-connected windmills is given by a low frequency oscill ation as the result of disturbances in the electric grid; (2) flicker, whic h is commonly explained by the dynamic wind variation, may also be caused b y mechanical eigenswings in the windmill mechanical construction. (C) 2000 Elsevier Science Ltd. All rights reserved.