ABSTRACT
Today, most of the energy needed for consumption is generated by burning fossil fuels, e.g. coal, oil and natural gas, in nuclear power plant or large hydropower stations. Power system is a complex technical system with main function to deliver electricity to end-users. However, the energy supply security and environmental protection challenges have led to increasing electricity production from renewable energy. Moreover, a sustainable energy system involves key components such as increased uses of renewable energy resources, efficiency and conservation or extended electricity in transportation. Over the last decades, diversification of the energy sources has become an economic, societal, national security and environmental imperative. Most common renewable energy sources for electricity generation include wind energy, solar thermal, photovoltaics, marine energy and geothermal energy. The development of renewable energy technologies has been maintained at high rates, proceeding at full speed. Future electricity distribution and generation with the extended uses of distributed energy resources require creation of new utility grid architecture. Economics, characteristics and the location of sustainable energy sources and distributed generation require these generators to be connected into power distribution rather than at transmission level. The benefits include increased energy efficiency, reduced fossil fuel consumption or pollutant emissions, enhanced supply security or economic activities. Major constraints renewable energy penetrations are the availability, non-dispatchability, intermittency and variability. In power systems, renewable energy promise lies in its potential to increase grid efficiency, reliability, supply diversification or power flow optimization. Parameters used in comparisons of renewable energy systems include efficiency, cost, initial investment, capacity factor, lifetime and technology maturity.
