The IEC 61850 standard has become the reference standard for substation configuration in smart electric grids, introducing data and service models to achieve interoperability between the network nodes. As the standard is currently based on the switched Ethernet architecture, there is a lot of work on its performance evaluation for guaranteeing real-time constraints. However, there still lacks a link between the substation configuration and its underlying Ethernet performance models (analytic or simulation). For bridging this gap, we propose in this paper a tool, called Simulation Tool for Analysis of substation netwoRkS (STARS) allowing the performance evaluation of any substation configuration through automatic generation of the corresponding simulation model from the Substation Configuration Description (SCD) file. STARS is based on the OMNeT++ simulator allowing the mapping of a real IEC 61850 system configuration to simulation parameters. It also provides a simple network configuration interface. This paper gives an overview of the STARS features through a simple example and points out its future evolution towards co-simulation of substation control algorithms, network performance, and electric grid behaviors.