In-Loop Adaptive Filters to Improve the Power Quality of Switched Reluctance Generator in WECS

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.