The aim of the paper is the analysis of the dynamic behavior of a thermoelectric power plant equipped with a steam unit and a gas turbine during the early phases ofa black-start-up maneuver for the network restoration. Models of different detail level for two production units and the relevant regulators have been implemented into two simulation tools. The paper contains the description of the different models, identifies the cases in which the two simulation codes predict similar results and presents the main characteristics, as well as the fields of application of the two codes. As an example, the paper presents also an application of simulators developed for the planning and the preparation of island operation and start up field tests of a power station.