In this paper generation and transmission expansion planning of Iran’s power system using equivalent load duration curve is studied. To this end, equivalent load duration curve for the whole system and each electricity region are calculated for years 2005 and 2010 using the expansion of the
probability random distribution series. The criteria loss of load probability, expected energy not supplied, and capacity shortage are computed using equivalent load duration curves. Equivalent load duration curves and the above-mentioned criteria are calculated using convolution method to validate the results
