A new hybrid multilevel back‐to‐back converter for doubly fed induction generator ‐based wind turbines' fault supportability

Abstract

Summary Wind turbines based on doubly fed induction generator (DFIG) have been increasing their participation in electrical grid. However, for these turbines, grid faults are a great issue. During grid voltage transients, the EMF induced on rotor is increased due to the sudden flux variation. High EMF leads to high currents on rotor circuit that could be hazardous to power electronics converter. A novel hybrid multilevel converter is proposed in this article. The proposed converter is the combination of traditional three‐phase converter and monophasic full‐bridge inverters connected in series with each phase. Employing this topology, it is possible to produce higher voltages in rotor circuit, which can oppose the machine‐induced voltage during the faults, limiting hazardous currents on rotor circuit. The design procedure and the voltage control strategy for the proposed converter topology are presented. Simulation results, considering symmetrical and asymmetrical faults, are presented for a 2 MW turbine. Rotor currents are restricted near to their nominal values, which ensure safety operation for the structure, especially for the power electronics. These results demonstrate the potential to replace traditional solutions and the effectiveness of the proposal as a protection circuit for DFIG by limiting currents and keeping power under control during voltage dips.

Wind Power Extraction Optimization by Dynamic Gain Scheduling Approximation Based on Non-Linear Functions for a WECS Based on a PMSG

“…A controller based on different algorithms for maximizing power coefficient is typically used to manage the MBC duty cycle. First, the power extracted from the turbine is adjusted, so the optimum turbine angular speed is reached [38][39][40].…”