Electrical and Computer Engineering ETDs

Publication Date

Spring 4-23-2020


This thesis paper proposes an optimal relay placement approach for microgrids. The algorithm separately calculates the System Average Interruption Frequency Index (SAIFI) of a microgrid in both grid-connected and islanded microgrid modes. The objective is to find the optimal relay locations such that the microgrid overall SAIFI is minimized. The power electronics interfaces associated with distributed energy resources may be classified as grid following or grid forming. As opposed to grid-following distributed energy resources (DERs) such as typical solar inverters, grid-forming inverters can control the microgrid voltage and frequency at the point of their interconnection. Therefore, these DERs can facilitate the formation of sub-islands in the microgrid when the protective relays isolate a portion of the microgrid. The exchange market algorithm (EMA) is used as the optimizing function. The effectiveness of the proposed optimal relay placement approach is verified using an 18-bus microgrid and IEEE 123-bus test system.


Microgrids, Protection, Optimization, Exchange Market Algorithm


Sandia National Labs

Document Type


Degree Name

Electrical Engineering

Level of Degree


Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Ali Bidram

Second Committee Member

Matthew Reno

Third Committee Member

Manel Martinez-Ramon