Protection and Power Smoothing of a DFIG/DC Microgrid Hybrid Power System With SMES-Based Unified Power Quality Conditioner

This paper proposes a unified power quality conditioner (UPQC) based on superconducting magnetic energy storage (SMES) for protection and power smoothing in DFIG/DC microgrid hybrid power system. The DC side of the UPQC is connected in parallel with the DC bus of the DC microgrid and maintains the stability of the DC bus voltage, while on the AC side, it is connected through series transformers to the DFIG terminal to act as a dynamic voltage restorer. For a case verification, a 0.8H/718A step-shaped superconducting coil (SC) is designed by finite element simulation using
H
-formulation to improve the critical current and economy of SMES. Finally, a dual control for regulating positive and negative sequence components of voltage signals is used in DFIG/DC microgrid hybrid power system. The simulation results show that it can effectively smooth the power of the hybrid power generation system, the key parameters of DFIG and DC microgrid can be well suppressed under fault conditions.