Wind power industry has grown a lot in the last few years and it will grow even faster in the next decade. Its participation in nowadays power systems is becoming more and more expressive every day, which brings difficulties for operation, certification and expansion planning, moreover investments in the area are growing in many countries. However this sector experiences a significant lack of data, because in most regions wind farms are very recent. Since this data is very important we propose a static methodology with physical background to extend existing short and medium term time series in order to obtain long term series.