The environmental concerns and restrictions of fossil fuel resources have led to the deployment of wind power installation. Due to the uncertain nature of wind speed, high penetration of wind power may threaten system reliability and security. Energy storage systems (ESSs) are considered to be a viable solution to this problem. In this study, a stochastic security constrained unit commitment (SCUC) problem is solved in the presence of wind and ESS units. The main concern of this paper is to study the impact of the proposed ESS model on the security and reliability of the system. To assess the reliability of a power system, the expected unserved energy (EUE) for line outage and demand underestimation contingencies is evaluated. The SCUC problem is solved by a scenario-based method incorporated with the Benders decomposition technique to mitigate congestions from power lines and provide feasibility and optimality of the solution in all the scenarios. The performance of the proposed approach has been evaluated using the 6-bus and 39-bus standard power systems. Simulation results demonstrated the economic advantages of the proposed model, while the security constraints are satisfied. Moreover, the impact of energy storage modeling on the EUE in post-contingency circumstances is discussed. (C) 2018 Elsevier Ltd. All rights reserved.