Abstract Frequency regulation has attracted considerable attentions with the integration of large-scale renewable energy into power systems. The de-commitment of conventional units reduces the system inertia, thus causes the poor frequency performance under high wind power penetration. Start-stop of conventional units is always set in power system simulations under high wind power penetration by default. In this work, power systems with deep peak shaving are considered in frequency regulation analysis for supplement. The system parameters of modern power systems in LFC are claimed and some assumptions are made first. The variety of regulating capability of conventional units and models of frequency sensitive wind energy conversion systems (WECS) are considered under different wind power penetrations. The simulation models are then derived according to the physical meaning of these two operation modes under different wind power penetrations. The modeling process is also improved by maintaining controllers optimal in each scenario. Load disturbances and stochastic wind speed are then employed as disturbance sources in the simulation tests. Results show that frequency oscillations of power systems with deep peak shaving would increase along with the wind power penetrations. However, compared with start-stop peak shaving, deep peak shaving can strongly keep systems away from large frequency deviations. Moreover, the regulation effects between the two methods become evident with increasing wind power penetration. The results would help system managers in daily operation.