  Solar Orbiter will observe the Sun and the inner heliosphere to study the
connections between solar activity, coronal structure, and the origin of the
solar wind. The plasma instruments on board Solar Orbiter will determine the
three-dimensional velocity distribution functions of the plasma ions and
electrons with high time resolution. The analysis of these distributions will
determine the plasma bulk parameters, such as density, velocity, and
temperature. This paper examines the effects of short-time-scale plasma
variations on particle measurements and the estimated bulk parameters of the
plasma. For the purpose of this study, we simulate the expected observations of
solar wind protons, taking into account the performance of the Proton-Alpha
Sensor (PAS) on board Solar Orbiter. We particularly examine the effects of
Alfv\'enic and slow-mode-like fluctuations, commonly observed in the solar wind
on timescales of milliseconds to hours, on the observations. We do this by
constructing distribution functions from modeled observations and calculate
their statistical moments in order to derive plasma bulk parameters. The
comparison between the derived parameters with the known input allows us to
estimate the expected accuracy of Solar Orbiter proton measurements in the
solar wind under typical conditions. We find that the plasma fluctuations due
to these turbulence effects have only minor effects on future SWA-PAS
observations
