Electrical energy systems (EESs) are systems which consume, generate, distribute and store energy at various scales. This paper presents a modeling and simulation framework that uses principles borrowed from the system-level simulation of digital systems and extends them to the case of EESs. The framework relies on open-source standards such as SystemC (and its Analog and Mixed-Signal extensions) for simulation, and IP-XACT for interface definition. The paper extends the IP-XACT standard with the formal definition of the interfaces of the typical components of an EESs. Then, it proposes a methodology to seamlessly plug such components into the simulation framework using the power configuration information contained in the IP-XACT descriptions. Simulations show that the proposed approach provides accuracy comparable to Matlab/Simulink results, with higher modularity and faster simulation times.