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Two strategies for wind power systems that simultaneously adjust the powers generation from doubly fed induction generator and achieves grid currents harmonic filtering are presented in this paper. The harmonic mitigation function is developed by algorithms proposed for compensating harmonics from the grid side converter. The quality of power is substantially enhanced. The generator side converter regulates the active and reactive powers that are supplied to the electric grid by the stator flux oriented control. This paper presents a novel control system for power generation and electric grid harmonic compensation, which is described and validated through comparison with other strategies. A harmonic filtering behavior analysis for some operation points using the novel strategy is presented. The proposed system efficiency is verified through simulation and experimental results. The grid current THD when none of the proposed strategies are applied is 17.21%. The THD is reduced to 5.68% when strategy 1 is applied. When strategy 2 is used the THD is decreased to 3.18%.INDEX TERMS Controllers design, doubly fed induction generator, integrated active filter, harmonic filtering, power quality, wind power generation.

In this work, a proposal is presented to mitigate the voltage ripple effect generated by switched reluctance generator (SRG) in wind energy conversion systems (WECS). Voltage and current oscillations of switched reluctance generators are an expected consequence of the machine's natural switching operation. This switching operation creates a known frequency component, named stroke frequency. When the SRG is connected to the AC utility grid in WECS, these oscillations may compromise the generated power quality by introducing stroke frequency components in the grid electric current. To solve such issue, this work has as an original contribution the proposal of in-loop adaptive filters applied to mitigate the propagation of the SRG stroke frequency content in the DC-bus voltage of a grid-connected WECS. The notch cascading and moving average filters are implemented at the voltage loop of the voltage source converter in an adaptive form, as function of the SRG speed. Simulation and experimental results show that the waveform distortion of the injected electric current is greatly reduced compared to the conventional non-filtered SRG connection.