This paper presents a detailed model for simulation of a Superconducting Magnetic Energy Storage (SMES) system. SMES technology has the potential to bring real power storage characteristic to the utility transmission and distribution systems. The principle of SMES system operation is reviewed in this paper. To understand transient and dynamic performance of a SMES system, a detailed SMES system benchmark model is given with extensive simulation results. This system is demonstrated using an electromagnetic transient program-PSCAD/EMTDC.