Packet Scheduling of GOOSE Messages in IEC 61850 based Substation Intelligent Electronic Devices (IEDs)

IEC61850 is a new international standard for communication networks and systems in substations that defines different message types based on their transfer time requirements. In IEC61850-based Substation Automation systems (SAS), Generic Object Oriented Substation Event (GOOSE) messages are used for conveying time critical information between the protection and control devices. In a switched SAS network architecture the switches are provided with a strict priority queuing discipline to provide higher priority for the real-time messages. However, the message scheduling inside the intelligent electronic devices is first in first out. The non-critical messages can add to the queuing delay of GOOSE messages during a heavy traffic congestion period. In this paper, different packet scheduling algorithms have been applied for SAS IEDs using an OPNET simulation tool. A sample SAS network is constructed based on IEC61850 specifications, and the effect of the different packet scheduling schemes in IEDs on GOOSE message delays is analyzed in detail. The comparison of these different packet scheduling schemes have been discussed from the results of the sample SAS.