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Dynamic Virtual Impedance based Second Order Ripple Regulation in DC Microgrids
S. Chaturvedi, , D. Patel
Published in Institute of Electrical and Electronics Engineers Inc.
The AC loads cause the DC bus voltage and the source current to oscillate at twice the AC supply frequency (fac). These oscillations have detrimental effects on sources and converter components. A distributed control strategy is proposed to regulate the current ripples propagating to the sources, in a DC microgrid feeding both the AC and DC loads. The proposed control methodology regulates the output impedance of the source interfacing DC-DC converter dynamically at 2fac. The impedance is increased virtually in series with the inductor of the DC-DC converter by a dedicated controller, which regulates the ripple magnitude according to the harmonic reference. Using this, the second-order ripple currents can be mitigated or propagated to the nodes having some ripple absorbing circuits, or filters. This improves energy density in ripple filters installed at a node and optimal usage of the DC link capacitor at node terminals is achieved. The proposed SRC regulation is analyzed in presence of component variations and communication delay between the nodes. A low bandwidth communication is incorporated so as to facilitate the per-unit current exchange between the nodes for the proportional DC load sharing. The proposed concept is verified through simulation and experimentation. IEEE
About the journal
JournalData powered by TypesetIEEE Journal of Emerging and Selected Topics in Power Electronics
PublisherData powered by TypesetInstitute of Electrical and Electronics Engineers Inc.