Responsiveness of Multi-Channel IEC-61850 Substation Communication Network Reliability Performance to Changes in Repair Factors

Power distribution centres distribute power to motor control centres in industrial facilities, as well as supply power to medium voltage drives among other loads. In reliability studies, the use of the combinatorial methods to evaluate the reliability of IEC-61850 based SCN in power distribution centres is preferred, owing to the ease of comprehension and applying the methods. The disadvantage of the methods is that repairs are assumed to be perfect and that all system faults are known; whereas it is not the case in practice. Markov model enables the impact of imperfect repairs on the system reliability performance to be investigated using the eigenvalue analysis method based on the concept of linear dynamical systems. The method presented in this paper advances the eigenvalue analysis method and focusses on the incremental responsiveness of the system to imperfect repair factors based on absorbing Markov chain and matrix calculus. The results indicate that even though the system is dependent on repair factors, the system is perfectly inelastic to the repair efficiency factors. However, the diagnostic coverage of the system is the most critical of the two factors, with higher elasticity as the factor approaches 100%. The results also indicate that both sensitivity and elasticity rapidly decrease as the diagnostic coverage of the system decrease. Thus, it is concluded that more emphasis must be put on the system diagnostic coverage because it is embedded in the system design, which can be expensive and practically not achievable once the system is commissioned and is running.