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This paper suggests a small-scale superconducting magnetic energy storage (SMES) to enhance the transient behaviors of a 100kWgrid-connected photovoltaic (PV) system, and conducts the conceptual design and performance evaluation. Considering the PV system requirements, the stored energy of the SMES is 90 kJ, and theYBCOtapes are adopted to make a solenoid SMES magnet. Based on the genetic algorithm, the magnet parameters including critical current, tape length, parallel and perpendicular magnetic fields are optimized. Using simulation tools, the effects of the SMES on the PV system are assessed, and the electromagnetic properties, stress, and loss of the SMES magnet are analyzed. The results prove that 1) the SMES improves the fault-ride-through capability and realizes an effective protection for the PV system. 2) A relatively large perpendicular magnetic field is found in both ends of the SMES magnet, and the maximum field is induced in the middle of the SMES magnet. 3) The maximum stress of the SMES magnet is acceptable, and the mechanical strength is satisfied. 4) The ac loss is crucial for voltage maintenance performance of the SMES at the fault. Under a short clearance time, the heat accumulation may have a moderate controllability. [ABSTRACT FROM AUTHOR]

In this paper, a flux-coupling-type superconducting fault current limiter (SFCL) is suggested to protect a 15-MW class doubly fed induction generator (DFIG)-based wind farm. Detailed conceptual design and performance evaluation of the SFCL are conducted. From the technical requirements and operational parameters of theDFIGwind farm, a 35-kV/500-A flux-coupling-type SFCL is designed, taking into consideration: 1) the winding type, core selection, and inductance values of the coupling transformer (CT); and 2) the structural style, tape length, and quenching resistance of the superconducting coil (SC). By use of different simulation tools, the electrical and electromagnetic characteristics of the SFCL are evaluated. The results show that the maximum magnetic field of the CT is 2.4 T, and the ac loss of the SC is 0.51W. Not only the electromagnetic properties and loss of the SFCL are acceptable, but also using the SFCL in the wind farm enables to suppress the fault current, compensate the voltage sag, and mitigate the wind power fluctuation. Thus, the robustness of the DFIG-based wind farm against the fault is enhanced, and the effectiveness of the proposed SFCL design is verified. [ABSTRACT FROM AUTHOR]