Design and Implementation of a SEPIC-Based DC Electric Spring for Voltage Stability Improvement of DC Microgrid

DC Electric Spring (DES) is a developing technology which is utilized to enhance the stability and reliability of power grids, specifically DC microgrid. When renewable energy sources like solar PV and wind are connected to the microgrid, there is a variation in the input voltage, and this variation affects the performance of the critical loads. Irrespective of variations in input voltage and load dynamics, DES is utilized to ensure a consistent voltage level across critical loads like telecommunication devices, biomedical equipment, etc. This paper presents the design of a DES utilizing a SEPIC Converter. Compared to the reported DES circuit architecture, the proposed SEPIC converter-based DES has a continuous input current, positive output voltage and a similar voltage gain as a buck-boost converter. The SEPIC converter used in the DES is designed for 200 W, 50 kHz to provide a regulated 48 V output across the critical load. To regulate the voltage of the DES, a PI controller is designed. The simulation results of the DES interconnected DC microgrid system is presented for a dynamic variation in system voltage from 30 V to 60 V. A hardware prototype of the designed DES is implemented and the results are presented.