Following an experimental investigation into suppression of a 2-D turbulent boundary layer separation with dielectric barrier discharge (DBD) plasma actuators, the present work investigates the concept numerically. The purpose is to develop and validate a simulation tool that captures the flow physics and carry out a parametric study of the concept at flow regimes beyond the current flow control capability of plasma actuators of conventional strength. First, a plasma actuator model is integrated into the commercial computational fluid dynamics (CFD) code ANSYS CFX to simulate the effects of plasma actuation. This computational tool is validated through comparison of results with the experimental results for pulsed actuation in quiescent air and for the control of a turbulent boundary layer separation at low flow velocities. It is shown that CFX with an integrated plasma model can capture the main experimentally observed effects of DBD actuators on turbulent boundary layer separation. Subsequently, this numerical approach is used, with increased plasma actuator strength, to study the influence of different actuation parameters (e.g., actuation location, direction and frequency) on suppression of turbulent boundary layer separation at higher flow velocities.