The rising energy independence and environmental concerns are key drivers in the growing popularity of plug-in hybrid cars (PHEVs). Studies indicate that for 90 % of the Americans who use their cars to get to work every day, the daily commute distance is less than 50 km - or 30 miles - and, on the average, the commuter car remains parked is about 22 hours per day. All the PHEVs have in common the batteries, which provide storage capability that can be effectively harnessed when the vehicles are integrated into the grid. Such storage capability can be used to effectively integrate wind power into the grid. By nature, wind power is intermittent which raises many challenges for the grid operator. The utilization of the storage from the PHEVs enables the power system operator to smooth out the output of the wind farms by storing energy when the wind power output is too high and releasing such energy when the power output is too low. We develop a probabilistic model to take into account the effect of the variability in the PHEV owner behavior and the fact that the PHEVs are not always plugged into the grid. The numerical studies show the positive levelization impact PHEVs can have on wind power operations when grouped in aggregations of large size.