A passivity-based decentralized control strategy for current-controlled inverters in AC microgrids

As a conventional stability analysis method of AC microgrid, the impedance based method needs a comprehensive impedance model of all the subsystems. It may fall short when the AC microgrid is interfaced by large number of converters with different parameters, or the microgrid has a time-varying structure, both of which would make the system modeling extremely complicated. This paper proposed a passivity margin criterion for AC microgrid, which decentralizes the stability target to each individual converter. The system will be stable with satisfactory margin as long as each converter is designed in accordance with the criterion, regardless of the system variations. A passivity realization approach for current-controlled LCL-type inverter is derived. The conclusions are verified on an OPAL-RT based Hardware-in-the-Loop platform.