FECT

Abstract: The phenomenon of energy sinking can be occurred when the total output of renewable energy sources (RES) is bigger than customer loads in the off-grid MG system, and the voltage of the battery system in the CVCF inverter of the MG system can rapidly increase depending on the state of charge (SOC), and then blackout in the entire MG system might happen due to the shut-down of the CVCF inverter. In order to overcome these problems, this paper deals with a transient operation strategy for a CVCF inverter-based MG system to prevent the shut-down of the CVCF inverter despite the energy sinking phenomenon. Based on the transient operation strategy, we implemented a test device for a 30kW CVCF inverter-based MG system in order to find out the transient operation characteristics related to energy sinking in the CVCF inverter. From test results based on a transient operation strategy, it was confirmed that the shut-down of the CVCF inverter can be prevented according to the SOC and voltage of the battery system in a CVCF inverter.

Keywords: Carbon-Free Off-Grid Micro-Grid System, CVCF Inverter, Battery System, Energy Sinking, Transient Operation Strategy, 30kW Scale Test Device.