Improved Performance of Doubly-Fed Induction Generator Wind Turbine During Transient State Considering Supercapacitor Control Strategy

This paper proposes a supercapacitor strategy for improving the capability of grid-connected doubly-fed induction generator (DFIG) wind turbines during fault scenarios. Supercapacitors are one of the important components in sustainable energy systems that are commonly used to store energy. In DFIGs, the supercapacitor is used to compensate for voltage dips and damping oscillations. In this work, a new topology of the supercapacitor system was used to investigate a DFIG wind turbine during transient state. The model system employed was a DFIG connected to the earlier wind turbine technology of fixed speed squirrel cage induction generator. Efforts were made to determine the effective parameters and switching strategies of the supercapacitor by considering different scenarios, in order to improve the transient state of the wind generator. The results obtained under severe grid fault were compared considering the different parameters of the resistance, inductance, and capacitance of the supercapacitor. The DC-link voltage and grid voltage switching strategies of the supercapacitor were investigated. Furthermore, the results of the proposed DFIG supercapacitor were compared with the traditional parallel capacitor scheme for DFIG system. For a fair comparison between the DFIG supercapacitor and parallel capacitor-based solution, the capacitance value considered was the same to buffer the transient energy.