Design and Testing of an Inverter-Based Combined Heat and Power Module for Special Application in a Microgrid

The basic design features of a new combined heat and power (CHP) module based on a reciprocating natural gas engine with generator coupled with a high efficiency inverter interface are presented along with test results obtained in the CERTS Microgrid program. The unique inverter interface enables the engine/generator to operate over a wide RPM range maximizing fuel efficiency, reducing emissions, while providing high quality electric power. This paper will focus on the application of this system as the platform for demonstrating the advanced software developed in CERTS Microgrid project with funding support from the California Energy Commission. The unique features of this control are demonstrated, including the ability to transfer between grid-tie and isolated modes of operation without supervisory controls interconnecting the modules. Application of this system in distributed generation (DG) markets for customers desiring products to serve the dual purpose of CHP and utility back-up power are also discussed.