The scale factor use of power installation of a certain type is called a share of their opperation in the overall energy system. As it known, the electricity production by power wind power plants is primarily related with wind conditions in region and has a stochastic character. The increasing of such power units share in the overall energy system balance also requires an increasing of power reserve capacity. This article estimates dependence of the time in the power shortage zone on the proportion of wind power plants in isolated power system. The special feature of this article is closely connected with the comparison of two approaches for the replacement of wind power plants in the energy system: individual nodes and system nodes. It is concluded that even in a small power system the combining of geographically distributed nodes with favorable and unfavorable wind conditions into a system can favorably affect to all nodes in certain ranges of the scales-factory.