Comparative analysis of degradation rates for inland and seaside wind turbines in compliance with the International Electrotechnical Commission standard

In order to identify and compare annual degradation rates of wind turbines, power performance testing was experimentally carried out on the Hankyeong (seaside) and Seongsan (inland) wind farms of Jeju Island, Korea. Five to six years' worth of raw nacelle wind data from SCADA system were analyzed for this work. Power curves were drawn for each year according to IEC 61400-12-1. The AEP and the CF were calculated by applying the drawn power curves to Rayleigh distribution, after which the CF yearly degradation rate was estimated. This constituted the methodology for degradation analysis in this work. The accuracy of this methodology was verified by comparing the relative error between the two CF degradation rates. The second degradation rate was calculated by applying the methodology to the wind data corrected by Nacelle Transfer Function. As a result, CF degradation rates for Hankyeong wind turbines 5 to 9 were found to have a relative error of 5.5% on average. The average CF reduction rates of the Hankyeong and Seongsan wind turbines were revealed to be 0.320%/year and 0.118%/year, respectively. The power performance degradation was found to have been faster for seaside wind turbines than for those located further inland. [Display omitted] •The wind turbine degradation is analyzed in compliance with IEC 61400-12-1.•The degradation analysis method using raw nacelle wind data is validated.•Performance degradation rates for inland and seaside wind turbines are compared.•Power performance declines faster for seaside wind turbines than for those inland.