In this paper the changes of power demand, power generation of oil-shale thermal power plants, the changes of wind power and interchange power are analysed. The analysis is made oil the basis of 2-second and 5-minute data acquired from Estonian power system. Front the analysis it is concluded that using of wind power plants in the power systems together with oil-shale power plants is quite limited. If the share of wind power should exceed this limit, notable losses in the ability to regulate power balance and power of oil-shale power plants may be caused.