With the increasing threat of terrorism around the world, more attention has been paid to the security of the electric transmission infrastructure. Events in countries like Colombia, which has experienced as much as 200 terrorist attacks on its transmission infrastructure per year, show the vulnerability of the power system to these kinds of events. Although it is very difficult to avoid or predict when and where these terrorist acts can occur, quick assessment of the situation can help operators to take the optimal actions in order to avoid cascading events and the consequent partial or total blackouts. Wireless sensor networks are becoming the technology of choice for sensing applications mostly due to their ease of installation and associated lower costs. This thesis proposes a novel conceptual design for an application of wireless sensor technology for assessing the structural health of transmission lines and their implementation to improve the observability and reliability of power systems. A two layers model is presented for overcoming the communication range limitations of smart sensors and two operational modes are introduced. The main goal was to obtain a complete physical and electrical picture of the power system in real time, and determine appropriate control measures that could be automatically taken and/or suggested to the system operators once an extreme mechanical condition appears in a transmission line. For evaluating the feasibility of the concept, a dispatcher training simulator (DTS) based on the energy management system (EMS) platform from AREVA T&D was used for simulating the operation of the electric power system in real time as it is monitored at an actual energy control center.