Harmonic and reactive currents sharing by multi-functional grid-connected inverters in a micro-grid

There are lots of power electronic converters, nonlinear loads, and reactive loads in a micro-grid, which may worsen the power quality and affect the stability, efficiency, as well as economical operation of the micro-grid significantly. A novel approach is presented to share the harmonic and reactive currents of a micro-grid using scattered multi-functional grid-connected inverters (MFGCI) without communication wires in this paper. Firstly, each MFGCI measures apparent power of detected harmonic and reactive currents at its grid-connected point. Then, a droop feature between compensation coefficient and the measured apparent power is utilized to determine the actual compensation currents shared by it according to its rated power. Because each MFGCI just need its own information to share compensation currents, a wireless operation can be yielded. Therefore, special features, such as N+1 redundancy and plug-and-play can be achieved. Finally, the feasibility and validity of the proposed approach is verified by power system computer aided design/ electromagnetic transient dc (PSCAD/EMTDC).