The Control of Rotor Side and Grid Side Converters in a DFIG During Network Voltage Unbalance Conditions Using Resonant Current Controllers.

This paper implements control techniques to enable improved operation of DFIG’s when subjected to the effects of network voltage unbalance conditions. The control scheme involves the integration of a resonant regulator into the PI controllers of both the rotor side and grid side converters in a DFIG. The resonant controller is tuned to twice the network frequency (2ωe) and designed to mitigate against the power oscillations and torque pulsations in a DFIG due to network voltage unbalance conditions. The grid side converter controller also incorporates a second resonant controller tuned to three times the grid frequency (3ωe) to alleviate the amplitude of the generated third harmonic currents. The control schemes of both the rotor side and grid side converters are coordinated to enable concurrent reductions in both the torque pulsations and the total DFIG power oscillations. A DFIG model is implemented in the program Matlab/Simulink and simulations show the reduction in power and torque oscillations and a reduction in the high unbalanced currents generated as a result of the applied voltage unbalance.

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