Within the context of the ESA-funded PARSEC activity, this work investigates the use of plasma actuators to control flow separation in over-expanded rocket nozzles. A parametric two-dimensional numerical study is conducted in preparation for a forthcoming subscale cold-flow experiment at Technische Universität Dresden. RANS simulations are performed using an in-house finite-volume solver, modeling the quasi-DC plasma actuator as a localized volumetric heat source. The actuator location and input power are varied to qualitatively assess their influence on the nozzle flow field under steady over-expanded conditions at a fixed nozzle pressure ratio. An additional high-temperature simulation performed with the Ansys^® Fluent software is used to verify that high-temperature effects have a limited impact on the flow behavior under the simulated conditions. The results show that plasma-induced heating can significantly modify the separation pattern and, in some cases, promote attached flow, while insufficient power provides limited control authority.