Operation and Control of Renewable Energy Systems

Chapter 14Renewable Energy Sources Integration in Microgrid

14.1 Microgrid

As discussed in the earlier chapters, the concern for climate change has resulted in the use of various renewable energy sources (RESs) to reduce greenhouse gases. These renewable sources are generally connected at the distribution level and are known as distributed generators or distributed energy resources (DERs). Using DER in distribution system reduces the physical and electrical distance between generators and loads. The presence of energy sources near the load contributes to enhancement of voltage profile, reduction in losses and postponing the investment in new transmission systems and large-scale generation. However, the effect of penetration of a large number of DERs is to change the pattern of power flow in the electric distribution systems. Currently, the relatively low penetration levels of renewable systems cause few problems. As penetration becomes greater, the available wind and solar energy become a greater problem requiring central generation to provide the power backup. Since these sources are intermittent sources and can cause stability problems found with intermittent loads such as roiling mills and arc furnaces, central generation or distributed generation (DG) or storage is required to provide this backup energy. Without storage and/or local generation, there is a technical limit to the amount of wind generation that can be added to the grid system, perhaps as much as 20% of the ...