This paper highlights some serious operating issues and challenges that are related to a parallel interlinking converters (ICs) interfacing an AC and a DC sub-grids of a hybrid AC/DC microgrid. These issue have not been investigated yet, especially in a hybrid AC/DC microgrid application. The first issue is the nonlinear load behavior of an IC during power exchange from AC to DC subgrid; which makes the IC acting like a harmonic voltage source that degrades the AC voltage and current. This behavior of the IC raises the second operation issue which is the circulating current that might exist in parallel ICs configuration. Seamless reconnection of an IC following abnormal operating conditions or schedule maintenance and the challenges associated with IC resynchronization are also examined. The paper also addresses in details the stability analysis, resynchronization issue and its effect on system stability. The theoretical expectations are verified by digital simulation using PSCAD/EM TDC simulation package.
Authors: Hasan Alrajhi, Ramadan El–Shatshat
DOI: https://doi.org/10.1109/ccece.2018.8447831
Publish Year: 2018
