Alfven frequency sweeping modes in stellarator plasmas with normal and reversed shear rotational transform are modelled using a reduced MHD model. We focus on a TJ-II dynamic discharge in which a sequence of frequency sweeping modes with a frequency sweeping range from 20 kHz to 140 kHz (Melnikov A.V. et al 2014 Nucl. Fusion 54 123002) have been observed. We find that for the normal shear iota profile a lower number of modes are present centred around 150 kHz of frequency while for radially extended low shear non-monotonic (NM) iota profiles, an extended spectrum of Alfv´enic modes is present covering a wider range of frequency from 115 to 295 kHz. Similarly, large number of discrete modes appear for relatively strong negative shear NM iota profiles having frequency range from 36 to 216 kHz. Results for the NM iota profiles with protracted discrete modes are in agreement with the extended frequency sweeping experimental findings. With strong negative shear one of the prominent modes (m = 7, n = 10/11) becomes narrower in radial width. An iota profile with strong negative shear and lower ιmin can therefore be considered more favourable for the Alfven eigenmodes (AEs) stability. Comparison of this mode’s frequencies calculated using standard dispersion relation and modelled through AE3D shows an agreement with the selection of ιmin values which supports the MHD spectroscopy calculations.