Multifunctional DC Electric Springs for Improving Voltage Quality of DC Grids

Abstract-Electric springs (ES) have been proposed as a distributed demand-response technology for mitigating voltage and frequency fluctuations of AC power systems fed by substantial intermittent renewable energy. This paper extends this concept to the development of DC Electric Springs (DCES) for voltage regulation of emerging DC power grids. The configurations of series and shunt DCES and their respective operating modes are explained. Both types of ES and their functionalities for DC bus voltage regulation, double-line frequency harmonic compensation and providing fault-ride-through support are discussed. The proposed DCES has been successfully applied to a 48 V DC microgrid system for experimental verification. The results show a good agreement with the theoretical analysis, confirming that the DCES can be an effective solution to provide simultaneous functions of DC microgrid bus voltage regulation.