Fault-Tolerant Control of a Low-Speed Six-Phase Induction Generator for Wind Turbines

In this paper, a fault-tolerant control scheme for a low-speed squirrel cage six-phase induction generator (SC6PIG) connected to a full-scale back-to-back converter structure is proposed and tested on an experimental 24-kW wind turbine test bed that represents a 1/100 of the electrical power of a grid-connected real wind turbine multiphase generator (2.5 MW). The aim of this paper is to define a suitable control algorithm that allows the electrical generation despite the loss of one to three phases on the generator or converter sides. Furthermore, the pole number of the generator is increased to simplify or eliminate the gearbox in such a way as to reduce mechanical sensitivity. Indeed, by multiplying the phase and pole numbers, the robustness against mechanical and electrical faults is improved compared to that of a classic three-phase generator associated with a gearbox. Simulation and experimental tests carried out on a 24kW-230V-24-pole SC6PIG in healthy and faulty mode (one phase missing) assess the feasibility and capacity of the proposed strategy.