A Modified Linear Contribution Factor Model for Improvement of Reliability Indices of Electrical Distribution Systems

ABSTRACT 

In Nigeria, a satisfactory degree of reliability has not been attained in our power systems in recent times. The average duration of interruptions that customers experience is quite high and the degree varies from place to place. This is evident all around the nation, most especially in urban commercial cities. Previous researchers have focused on the assessment of power system reliability indices using different models. In this work, a computationally efficient modified linear contribution factor model (LCFM) is developed. The model can be used for the appreciable improvement of all the major system reliability indices of practical distribution systems, unlike the conventional LCF model which can only improve some of the system reliability indices of practical distribution systems. Data collection and data analysis were carried out to develop the LCF model used on the three selected distribution systems on the Nigeria National Grid. The result of this work indicates that part of the reliability indices computed for the distribution systems SAIFI is more sensitive to the LCF model than SAIDI and CAIDI but that the sensitivity is low for SAIDI index compared to CAIDI. This is due to the quantization of the annual number of customer interruptions caused by the type and placement of protective devices on the distribution system of the National Grid. With the use of the modified LCF model, the average percentage improvement in the system reliability indices becomes 97.72%. 98.55% and 98.63% for Ibadan, Ilorin, and Ikeja distribution system respectively as against an average percentage improvement of 36.08% 11.36%, and 24.36% in the system reliability indices for Ibadan, Ilorin, and Ikeja distribution system respectively with the use of conventional LCF model. The result of this research work confirms the efficiency of the modified LCF model.