Multi-port Energy Router for DC Grid Clusters

Abstract

DC micro-grid comes an increasingly popular solution for local energy integration and dispatch. Individual DC micro-grid can operate in both island and grid-tie mode. The past research mainly focused on the DC-AC grid-tie power management while DC-DC tie mode might dominate future smart power distribution networks. This paper proposed a multi-port energy router concept to multiplex DC power from multiple DC communities whose bus voltage is operated at very close levels. The proposed partial power energy router works as a Kirchhoff’s current law (KCL) “super node”. It includes a partial power topology which can direct the DC current flow between any two buses or to the local energy storage by only taking the bus voltage differences. To fit the modulation and control into industrial standard framework, also considering the flexibility of controlling the energy storage current, multidimension space vector modulation and modified instantaneous power theory are proposed to regulate the DC power flow. The power transfer efficiency of standard half-bridges partial power topology is verified experimentally. Multiple operation scenarios are investigated to prove the feasibility of the energy router through simulation and experiments.