Technical requirements of Distributed Generation facilities and their impact on the operational performance of isolated power systems

In recent years, the electric power systems are adopting new technologies in their structure in order to achieve better performance and efficiency in the electricity production, transmission and distribution. The operation of independent power producers under the framework of the competitive electric energy market as well as appropriate financial incentives being developed worldwide has increased significantly the penetration of the Renewable Energy Sources into the power systems. These generating units together with units using other technologies, such as the combined heat and power generating units, consist the Distributed Generation facilities while considerable research effort has been devoted recently concerning their impact on the operational performance of power systems. Especially in the case of isolated power systems additional attention needs to be given since these systems face specific problems that are related to their planning and operation when compared to the interconnected ones. The purpose of this paper is to describe the main aspects of the various types of Distributed Generation facilities that may be installed in isolated power systems. The paper is concentrated in various issues such as the technical performance of the respective generating units, the existing forecasting methods of power generation, the power quality issues, the participation of renewable generation into ancillary services and the appropriate actions of the transmission system operators.