Modern Energy Management (MEM), a renewable energy development services provider, is planning to develop wind power plant in Indonesia. The wind power plant shall be connected to the existing PLN grid network. Since the wind power plant will be connected to the PLN grid, then it must follow and meet grid requirements. As the first step in connecting a wind power plant, a preliminary assessment of the existing grid is needed. The main concern of this preliminary grid assessment is to analyse the potential substations as the connection point of the wind power plant and identify the flaws in the potential export substations. There are many things to be considered to determine optimum connection point from the wind power plant to the existing power system; tapping to existing transmission lines or build switching substation, and cost estimation for each configuration.