Role of switching devices on microgrid reliability

Distributed energy resource (DER) units are connected to the trunk feeder of microgrid by different types of switches. Reliability of microgrid is dependent to a large extent on the mode as well as speed of operation of these switches. Isolator and circuit breaker are the two such options as switching devices. In this paper, authors investigate how different types of switches influence the reliability of a 6-bus radial microgrid. in this context, they assess the reliability of the system, separately, with isolator and circuit breaker types of switching connections of DERs to the trunk feeder. Reliability indices SAIFI, SAIDI, CAIDI, ASAI, ASUI and EUE are determined for each of the switching cases and then compared. Net present value (NPV) benefits from reduction of customer interruption cost (CIC) due to above two switching connections are also evaluated, here. CIC is the main guiding factor for assessing the worth of reliability. Outages of sub-station, trunk feeder sections, and substation circuit breaker along with stuck breaker conditions are included in the studies for calculation of indices and only, first order failure modes are addressed.