The use of IEC 61850 communication protocol has more widely applied in electrical engineering, it presents new challenges to real-time performance simulation and testing of protective relays. In this paper, the OPNET Modeler simulation software has been used for the modeling of intelligent electronic device (IED) in substation level network. Based on simulations, different types of data stream have been discussed, such as, periodic data stream, random data stream and burst data steam. The specific studies using these models to construct substation automation system (SAS) network on OPNET modeler was made to reveal the influence of each factor to the real-time performance, which is also included in this report.