Impact of Quality of Repairs and Common Cause Failures on the Reliability Performance of Intra-Bay IEC 61850 Substation Communication Network Architecture Based on Markov and Linear Dynamical Systems

Modernisation of substations using digital-based Substation Communication Networks (SCN) enables the automation of substations, allowing effective and efficient monitoring of substation equipment and implementing complex control and protection schemes. The IEC 61850 standard for SCN’s objective is to integrate substation devices from different vendors, enabling peer-to-peer communication between the devices. The reliability investigation of the IEC 61850 based SCN architecture continues since it is left to the system designer to determine based on the network’s applications and functions. In all endeavours to designing highly available SCN architectures, redundant systems are employed in mission-critical applications. In this paper, the impact of Common Cause Failures (CCF) and the quality of repairs on the reliability performance of IEC 61850 based architecture are investigated using the Markov process and Linear Dynamical Systems, where the diagnostic coverage level of the system is based on the ISO 13849-1. The results of the case studies indicate that common engineering design and coupling factors have a negative impact on the system reliability performance, notably for systems with high diagnostic coverage. The results also indicate that the factors have less impact when the system diagnostic coverage is low, specifically at low repair efficiency levels. However, the impact becomes more pronounced as the repair efficiency increases, as observed from the responses of the transition probability matrix’s eigenvalue magnitudes. Thus, it is critical to ensure the minimum impact of common engineering design and coupling factors by diversifying the system’s subsystems to ensure a high independence level.