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Reliability Forecasting in Distribution System Considering Variable Failure Rate: Combination of Equipment Inspection Method and Weibull Analysis

Ohn Zin Lin(1*), Hajime Miyauchi(2)

(1) Power System Research Lab, Kumamoto University, Japan
(2) Power System Research Lab, Kumamoto University, Japan
(*) Corresponding author



System reliability estimations typically use average equipment failure rate. However, it has a fatal weakness when considering the reliability index due to the accuracy of the failure rate. In practice, the failure rates of lines, protection devices, transformers and dispersed generation (DG) vary over their working time. In this paper, the variable failure rate (VFR) of system equipment is obtained using equipment inspection method (EIM) according to the condition score and their working ages. Based on the different failure rates, reliability probabilities of each component are forecasted using regression equations and the Weibull distribution method (WDM) for different working ages. System reliability is then analyzed using the reliability combination method for long term viability. The impact of life expectancy or setting of the maximum usable condition of components is determined. According to the quantitative results, reliability conditions are estimated more accurately based on different working ages.
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Equipment Inspection Method; Maximum Acceptable Condition Score; Reliability; Variable Failure Rate; Weibull Distribution

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