Design of an electric spring for power quality improvement in PV-based DC grid

Abstract

Electric Spring (ES) concept has been emerged based on the mechanical spring concept. ES can be employed in AC or DC grid for demand side management, and improving the power quality and energy management. Renewable Energy Sources (RESs) are intermittent in nature, so the ES is introduced in the DC grid for stabilizing the voltage fluctuations incurred by the RESs power changes such as PV systems. The DC ES is inserted in the DC grid in series with the non-critical loads (e.g.Thermostatically controlled loads as air conditioning systems, electric water heaters and refrigerators or charging of charging of plug in electric vehicles) forming a smart load. In this paper, a comparison between the series and shunt DC ES is held considering four different operation modes. An ES based on four-quadrant DC-DC converter is analyzed and designed for providing a bi-directional power flow. To explore the effect of the series ES on the non-critical load, simulation results for both open and closed loop operations, using Matlab/Simulink, are shown to validate the presented approach. Moreover, experimental results are presented for a prototyped ES. ? 2018 IEEE.