DC electric springs - An emerging technology for DC grids

There is widespread attention on integrating renewable energy sources, such as the solar power, to DC distributed power systems and DC microgrids. The voltage stability and the power quality issues are of concern if a large proportion of power sources in these DC power systems are generated by intermittent renewable energy sources. This paper presents an electric active suspension technology known as the DC electric springs for stabilizing and improving the quality of the power distributions in DC power grids. The basic operating modes and characteristic of a DC electric spring under different types of serially-connected non-critical loads will first be introduced. Then, various potential issues that affect the power quality of the DC power systems, namely the bus voltage instability, voltage droop, system fault, and harmonics, are briefly addressed. Laboratory-scale experiments validated that the aforementioned quality issues can be mitigated using the proposed DC electric spring technology.