By 2030, the Australian government intends to increase the market share of electric vehicles by at least 50%. This paper investigates the effect of the upcoming large-scale implementation of plug-in hybrid electric vehicles (PHEVs) in Australia on thermal power generation expansion decisions and integration of wind power into New South Wales (NSW), the largest regional market in the Australian National Electricity Market (NEM). Furthermore, seeking to understand whether optimizing and allocating PHEV charging loads can effectively decrease investments and operational costs of the power system with high wind penetration, we also evaluate the potential cost savings from the dedicated governmental charging strategy of PHEV fleets. To this end, we develop a Mixed Integer Linear Programming (MILP) optimization model for optimal power system investment decisions. The simulation results demonstrate that, grid-connected PHEVs obviously increase power system financial and operational burdens. When compared to the scenario with dumb charging strategy, smart charging strategy results in less investment in thermal generation and flatter load curve, as well as less wind curtailment.