Effect of Prime Mover's Characteristics on the Survivability of a Synchronous Generator during Transient Overload Conditions

Recently, prime-mover stalling phenomenon was observed in a synchronous generator-based DER for large step load changes during experimental testing at the CERTS Microgrid. It is found to highly impact the generator's survivability during transient overload conditions. The stalling occurs in synchronous generator-based DER because of a sustained imbalance between electrical load demand and mechanical power available from the prime mover, thus depleting the generator's stored kinetic energy. In particular, mechanical power capability of the prime mover and stored kinetic energy in the rotating mass are the contributing factors. Therefore, this paper evaluates three different prime movers for DER survivability. The characteristics of most commonly used prime movers such as a reciprocating engine and gas turbine are investigated during transient overload conditions by case studies using PSCAD/EMTDC software.