Distributed Generation System Impact Analysis with Computer Modeling Tools

The number of applications for Distributed Generation (DG) interconnections received by utility system operators is increasing every year. As the various DG technologies mature and the cost per kilowatt of generation goes down, utilities may receive more applications for generation interconnections large enough to require detailed system impact analysis before approval. Many utilities are already performing their own system impact studies, or are planning to begin doing so in the near future. A number of computer-based analysis programs are available that can model generation resources, with varying degrees of complexity. Utilities that are already performing their own studies need to be completely familiar with all of the capabilities of the particular tool or tools they use, and should have a reliable procedure in place for performing their analyses. This paper will examine the process of performing a DG system impact study with a computer-based system modeling tool. Topics of discussion will include information and data needed for accurate modeling, using various types of generator models, correctly adding generation to existing models, types of analysis that should be performed, common errors in modeling and analysis, and general best practices for completing system impact studies. Practical experience gained from performing many DG studies for utilities using several widely-available modeling tools will be shared.