Protection System Reliability Assessment Considering Smart Grid Technologies

Advanced protection systems and peer-to-peer communications are major assets in a smart grid platform. Failures of protection system components play a significant role in the outage events of breaker oriented power systems and protected components. The recent developments in nonconventional protection systems and the widespread use of intelligent electronic devices (IED) supported by advanced peer-to-peer communication systems could lead to unexpected protection system failures, which can result in circuit breakers not opening when required. A protection system is a completely integrated system of its own which can be analyzed independently of the power system network or component that it is intended to protect. An independent analysis enables sensitivity and comparative studies to be made of alternative technologies and protection schemes. This paper presents and discusses different alternative digitized protection schemes supported by an IED and a communication system. The reliability of each scheme is assessed using event tree analysis (ETA). An application to a breaker oriented system is illustrated. Sensitivity analysis is conducted to assess the effect of the protection system component. Evaluation results show that an IED supported by a robust communication system can improve the protection system reliability, especially for highly redundant protection systems. The paper illustrates that high penetration of advanced technologies in protection systems must also be associated with highly reliable components for enhanced system performance.