Improvement of islanded operating stability for lean-burn gas engine by effective use of power storage device

In these years, gas engine generators have been much improved to gain higher electrical efficiency by using lean-burn and miller cycle technologies. As on-site power generation, electrical efficiency of over 40%LHV can be obtained by several hundreds to several thousands kWs units. In addition to obtaining a highly efficient power utilization by interconnected operation, emergency power could be supplied by an islanded operation that is the most distinctive ability of distributed generators to keep social infrastructure from disasters. However, high-efficient gas engines are not suitable for islanded operations because of the instability during load changes. Even though interconnect operation, the limitation of load increment is imposed for the system operation, in which gas engines need several minutes for load increment from 0kW to the rated load. In this study, we describe a highly efficient lean burn gas engine combined with power storage devices, which will establish operation stability during islanding mode. We will demonstrate the design of cooperative control between two power sources to derive better performance by the integration.