A Hybrid Superconducting Fault Current Controller for DG Networks and Microgrids

Recently, not only the penetration level of distributed generation units (DG units) has been rapidly increasing but also the connection of microgrids as a developing technology to the existing distribution networks has attracted much attention. This may raise issues such as bidirectional power flow, excessive shortcircuit level, reclosing, and protective coordination that need attention. Superconducting fault current limiters are known as one of the best countermeasures to solve the problems related to the excessive short-circuit level in DG networks and microgrids. Different amounts of fault current may flow in such grids as the grid topology changes. Not only the fault current must be limited in such networks but also it should be controlled in order to be maintained in an appropriate range. This will ensure suitable coordination of the protective devices and, subsequently, safe operation of the grid. We introduce a hybrid superconducting fault current controller (hybrid SFCC) in this paper, which is suitable for DG networks and microgrids, without any dependence on grid monitoring technology. Finally, a case study on a microgrid containing the hybrid SFCC has been conducted to investigate the device performance.