Impacts of plug-in hybrid electric vehicles charging on distribution grid and smart charging

Large-scale development of plug-in hybrid electric vehicles (PHEVs) will have the most direct impacts on the distribution grid. PHEV charging impacts to the distribution grid are analyzed through a residential feeder of 10kV in a city from aspects such as load profile, power loss, voltage quality, and several penetration level scenarios are discussed. The results indicate that uncontrolled charging will pose great pressure to the grid on high penetration level and reasonable PHEV penetration may be helpful to the grid's economic operation. Smart charging method is explored which can optimize the chargeable power in each period by the short-term load forcast while meeting the charging requirements, and achieve smoother load profile, less power loss and better voltage quality.