Optimized Control of active loads in DC microgrids with virtual energy storage

Abstract

In DC microgrids, optimized control of the active load is critical to achieving economic benefits and a stable DC voltage. In this paper, first, the conversion relationship between the rotational kinetic energy of a motor and the storage energy of a super capacitor is established for integrating the load capacity with the current energy storage system. Second, the virtual energy storage device (VESD) is emulated by the active loads, which have the same operating parameters as those of an actual super capacitor. Third, a novel economic management scheme for the DC microgrid with VESD is proposed, considering the product revenue of load and the life loss of the battery. In addition, to further improve DC microgrid stability, the system operating range is divided based on the voltage hierarchical control, and as a result, the active load in the form of a VESD has a proper sequence to participate in voltage regulation. Last, the test results demonstrate that the microgrid can obtain significant economic benefits. In addition, the dynamic stability of the DC voltage can also be improved thanks to the simpler coordination between the actual ESD and VESD.

Keywords

• Virtual energy storage
• Active load
• Super capacitor
• Hierarchical control
• DC microgrid