Nowadays, it is necessary to meet the demands of the increasing energy supply, to provide continuity and quality standard. Renewable energy systems are at the forefront in this regard. This paper includes some conclusions based on the dynamic OPF analysis of the IEEE-30 bus test system and then considering the case of the renewable power plants. The behavior of voltage stability and phase angle in both cases is studied. In first case, only the standard IEEE-30 bus test system is used and both the stability of voltage and the phase angle are examined. Later, the thermal power plants located at 5, 11, 13 bus are replaced with renewable energy power plants and the effect of renewable energy power plants on stability is examined. Wind and solar power plants are used as renewable energy power plants.