A Method for Performability Study on Wide Area Communication Architectures for Smart Grid

An extensive use of ICT is a key feature in the development of next generation smart grids. The ability of the ICT system to meet the real time requirements of the powers system, even when it is degraded due to failures, is essential. This simultaneous study of dependability (reliability) and performance are referred to as performability. This paper presents a method for a performability study on ICT support system of smart grid. It looks into how performance associated properties (timing failures) can be modelled together with properties affecting dependability such as omission or conventional component failures. A two tier model using ns-3 and SAN is developed to study the peformability of an IEC 61850 based communication infrastructure for a protection application. For illustration, a simulation is conducted to study the reliability and unavailability of an IEC 61850 based communication architecture, where the impact of both timing failures and omission failures are investigated and compared. The result revealed that the availability and reliability is highly dependent on the requirements for the protection application, maximum delay per packet and maximum number of consecutive delayed packets the protection application can tolerate. It also shows that timing failures have a higher impact than omission failures for a protection application with shorter time requirement.