M. Saleh and  H. Bevrani,  Frequency Regulation Support by Variable-Speed Wind Turbines and SMES.   journal   = {International Journal of Electrical and Computer Engineering}, [online]. World Academy of Science, Engineering and Technology.
    May 2010, vol. 41(5). 881 - 885
    [viewed 14 October 2019]. Available from: https://publications.waset.org/pdf/12074.