Summary: | The increasing of large-scale wind power integration capacity brings great challenges to the safe
operation and management of power grid. Modern grid codes put forward the
requirements of fault ride through (FRT) capability: (i) to remain continuous
operation at a given time; (ii) to contribute to support the voltage stability
during FRT by providing reactive current. Aiming at the FRT problem of doubly
fed induction generator (DFIG), critical elements of the rotor side converter
(RSC) and the grid side converter (GSC) to FRT are analysed, and the improving
RSC control scheme, adding extra hardware equipment, and improving reactive
current control scheme are studied. Matlab/Simulink simulation studies are
conducted to verify the effectiveness of the proposed strategies. The results
show that when the grid fault is light, the improving RSC control strategy can
effectively control the rotor winding overcurrent, when the grid fault is
serious, it needs additional hardware equipment; the coordinated control
strategy of the RSC and the GSC providing reactive current support is identified
as the most advantageous approach because it not only provides enhanced reactive
support for the grid, but also avoids over-speed risk of DFIG based wind turbine
shaft.
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