Interaction of the Substation Load Tap Changer with the High Penetration of Distributed Energy Resources

The interaction between the high penetration of distributed energy resources (DERs) into the distribution grid and the substation load tap changer is investigated in this paper. This interaction reveals the effects of the high penetration of DERs on the distribution systems. For instance, effects on the flicker and voltage profile of the distribution network. Three distribution feeders of Entergy Corporation were considered as the tested network. The distribution system is modeled in OpenDSS software. It is shown that the upstream LTC has a considerable number of operations during the high penetration of DER units. This excessive operation causes more fluctuation in the voltage profile, i.e., higher flicker. Moreover, this excessive operation can damage the substation transformer and cause a blackout in all downstream feeders. The LTC operation mode such as Ignore and Block is shown to have a significant impact on the number of LTC operations during high penetration of DER.