Coping with wind power variability: How plug-in electric vehicles could help

Plug-in electric vehicles could offer flexibility for wind power and an attempt was made to quantify the effect with a power system model Wilmar. Wilmar simulates unit commitment and dispatch using mixed integer programming and includes wind power and load stochasticity as well as a module for plug-in electric vehicles. Forecast errors of wind power increase the need for balancing and ancillary services. The model is able to use the plug-in electric vehicles (PHEVs) to participate in the balancing and ancillary services and decrease the costs of these services. The charging and possible discharging of the vehicles can also be optimized to most beneficial hours within the limits caused by vehicle use. We have calculated the benefits at different PHEV penetration levels. The results indicate that benefits of peak shaving using vehicle to grid are limited due to the rather small size of storage in the batteries even with a large number of vehicles. Benefits can best be seen in the smart charging of the vehicles and in the correction of forecast errors. The marginal benefits of introducing PHEVs capable of smart charging and discharging are high for low numbers of PHEVs in the power system, but declines with higher penetration levels of PHEVs, because the demands for power system reserves and flexibility are limited.