DC microgrid stability control with constant power load: a review

Abstract

The DC microgrid has the advantages of high energy conversion efficiency, high energy transmission density, no reactive power flow, and grid-connected synchronization. It is an essential component of the future intelligent power distribution system. Constant power load (CPL) will degrade the stability of the DC microgrid and cause system voltage oscillation due to its negative resistance characteristics. As a result, the stability of DC microgrids with CPL has become a problem. At present, the research on the stability of DC microgrid is mainly focused on unipolar DC microgrid, while the research on bipolar DC microgrid lacks systematic discussion. The stability of DC microgrid using CPL was studied first, and then the current stability criteria of DC microgrid were summarized, and its research trend was analyzed. On this basis, aiming at the stability problem caused by CPL, the existing control methods were summarized from the perspective of source converter output impedance and load converter input impedance, and the current control methods were outlined as active and passive control methods. Lastly, the research path of bipolar DC microgrid stability with CPL was prospected.

Keywords

constant power load (CPL) / DC microgrid / voltage balancer / stability criterion / cascaded system / virtual resistance

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