This paper deals with a methodology to model a dynamic interconnected system in low power network, as shipboard electric network. A global state space model describes the whole system behavior in both steady and transient states. As the rotor of the synchronous generator is not completely accessible to measurement, it will be described by black boxes. Its parameters can be identified by SSFR tests. The modeling methodology enables to resolve the various coupling between rotor, stator and load. To build the global multi-generator model, a common frame is defined, then each network’s component is modeled in this frame and finally the whole system’s model is build thanks to relations connecting the different state vectors.