Plastic deformation is due to the collective motion of large numbers of dislocations. A new algorithm is presented to determine equilibrium configurations of dislocations as a function of temperature and strain rate. The equilibrium is achieved by minimizing the total interaction energy of the dislocations and then thermal activation mechanism is incorporated at appropriate time scale. This approach allows decoupling of time scales associated with dislocation glide and it gives access to strain rates that are of interest in practical applications. We verified our new quasi-static method by comparison with full dynamics simulations. Numerical examples show that the new model can capture rate effects over 6 orders of magnitude change in the applied strain rate, with negligible change in the simulation time.