An electric power system is a network of electrical components used to supply, transmit and use electric power. Burning coal produces sulfur, nitrogen oxide and mercury emissions and causes disastrous environmental and health consequences. In addition to environmental issue, fuels such as coal, oil, and natural gas are non-renewable. Once a deposit of these fuels is depleted it cannot be replenished. Thus, the renewable energy has been widely emphasized in the world. Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable. Renewable energy sources are continually and naturally replenished in a short period of time. Renewable energy sources differ from conventional sources in that, generally they cannot be scheduled, and they are often connected to the electricity distribution system rather than the transmission system.