Influence of yaw control on flicker produced by wind turbines

Abstract

IEC 61400-21-1 describes the procedure for measuring the flicker produced by a wind turbine. This is a complex procedure, as it involves the processing of voltage and current time series recorded in a grid connected wind turbine for its entire operating range. The standard assumes that the flicker produced by a wind turbine is related to wind variations and switching operations. The voltage and current signals recorded in a 2 MW Type III wind turbine located at a 32 MW wind power plant in Spain were used for the study. The work shows that most of the flicker produced by the wind turbine is due to the power consumption of the motor used by the yaw control system to orient the nacelle. These operations generate voltage changes whose amplitude is independent of the generated power. As the generated power increases, so does the number of yaw control operations and thus the flicker emitted. A simple analytical method is proposed to estimate the flicker produced by yaw control operations. The results confirm that incorporation of this strategy into the standard could considerably simplify the current flicker measurement procedure.