An adaptive protection strategy for reliable operation of microgrids

The rapid growth of population resulted in significant increase in power demand. Furthermore, the consumption areas are developing dramatically. Thus, the generation of adequate electricity is necessary to meet the increasing loads. One of the reasonable solutions is installation of Distributed Generators (DGs) ranging from small scale micro turbo-generators to renewable energy sources near the demand centers. Although, studies show that DGs impact negatively conventional power system protection in Distribution Network (DN) level. Change in power flow direction, change in nominal current passing through the line, etc are examples of these negative effects. Therefore, they have a potential to disturb preexisting coordination in protection systems. This paper presents an automatic adaptive protection strategy for reliable and secure operation of microgrids. The proposed adaptive protection scheme is based on pre-calculated settings for overcurrent protection relays of a DN model developed in DigSILENT Powerfactory software The overcurrent relays' settings are adjusted automatically to keep the CTIs (Coordination Time Intervals) as before while experiencing a new scenario such as a DG integration.