  Because of the infrared renormalons, it is difficult to get power accuracy in
the traditional approach to the Wilson's operator product expansion. Based on a
new perturbative renormalization scheme for power-divergent operators, I
propose a practical version of the OPE that allows to calculate power
corrections to desired accuracy. The method is applied to the expansion of the
vector-current correlation function in QCD vacuum, in which field theoretical
status of the gluon condensate is discussed.
