Analysis of Limiting Bounds for Stalling of Natural Gas Genset in the CERTS Microgrid Test Bed

Natural gas powered distributed energy resources (DERs) are gaining more popularity due to the recent discoveries of huge natural gas reserves in several places. These DERs however suffer from the tendency to stall under large load fluctuations owing to the fuel map limits present in the engine governors and the inherent time lag in torque production. A critical analysis of the stalling causes is conducted for a natural gas engine powered synchronous generator (referred as genset) that was installed in the CERTS Microgrid. The grazing phenomenon is explored for analyzing the stalling behavior. Simulation studies are performed for different test case scenarios, and it is shown that such DER units can operate reliably near their rated capacity without stalling if the load changes are effected in a proper manner. The ability to handle load changes in such gensets without the need for any load reliefs is analyzed and the possible solutions are discussed for avoiding such stalling occurrence.