Modeling and control of a natural gas generator set in the CERTS microgrid

The recent addition to the CERTS microgrid was a commercial off-the-shelf natural gas engine generator set, also referred as gen-set. With this incorporation, the CERTS microgrid that earlier consisted of the same kind of inverter-based combined heat & power (CHP) distributed energy resources (DERs), has got transformed into a diverse/mixed microgrid. As the gen-set came equipped with an isochronous speed governor and ac brushless type exciter, a few enhancements became necessary for augmenting it with CERTS controls that enable capabilities of plug-and-play operation, and seamless islanding and reconnection with the utility grid. This paper describes the modeling and control of gen-set. The models developed are validated with experimental testing against large step changes in load. Performance of gen-set with CERTS controls is demonstrated in different modes of operation of the mixed microgrid.