Effects of Distributed Generators from Renewable Energy on the Protection System in Distribution Networks

The increasing number of distributed generators especially from renewable energy requires investigating the impact of their integration on the protection system. This paper evaluates the effects of distributed generators on protection relays functionalities (over current protection and backup protection) in the medium voltage grids. In order to obtain profound results, simulations were done on several realistic scenarios of an existing medium voltage grid. As all short circuits were simulated in the time domain by using the software Power Factory from DIgSILENT GmbH, dynamic models for distributed power generation had to be implemented. The results were analyzed graphically and tested for negative influences on the protection functions. In addition, simulation was also done to study the effects of the realistic future requirements for the increasing number of distributed power generation in the future. The results from these simulations are presented and discussed.