Models for predicting flicker induced by large wind turbines

Accurate models for voltage flicker prediction are required so that large wind turbines may be connected, to weak utility networks, in the confidence that excessive flicker levels will not occur. These models must work satisfactorily with different wind turbine designs so that risks to manufacturers, intending to adopt a particular type of turbine, are minimised. This paper presents a simple model for identifying critical busbars, where the levels of flicker may be high. It also describes a more complex model for accurately predicting flicker induced by operating wind turbines. The models are very flexible and were developed specifically to be coupled to an existing dynamic model of an entire wind turbine. The various models representing static and dynamic loads are described and their impact on flicker are investigated. In addition, the effects of the X/R ratio and fault level of the network are discussed. Various wind conditions and different network parameters have been simulated. Results are presented from simulations carried out using measured wind turbine power time series and data from operating wind farms