| Index Category | Specific Index | Definition (Billinton’s phrasing) | | :--- | :--- | :--- | | | LOLP | Probability that the load will exceed available capacity at a given time. | | Frequency | LOLE | Expected number of days (or hours) per year that a deficiency exists. | | Duration | LOLD | Average duration of each deficiency event. | | Energy | EENS | Expected Energy Not Supplied (in MWh). Used for economic costing of failures. | | Customer | SAIFI | System Average Interruption Frequency Index (customer-centric). | | Customer | CAIDI | Customer Average Interruption Duration Index (restoration speed). |
He proved that EENS (Expected Energy Not Supplied) is the single most valuable index for cost-benefit analysis. If you cannot monetize the reliability solution, you cannot justify the investment. Part 5: The "Billinton Solution" in Practice – A Worked Example Consider a small industrial power system: Two parallel gas turbines (20 MW each, failure rate 5/year, repair time 50 hours). Load = 25 MW. | Index Category | Specific Index | Definition
Billinton’s solution can be summarized in one sentence: "Reliability is not a binary property (reliable/unreliable); it is a continuous, measurable, economic risk." | | Energy | EENS | Expected Energy Not Supplied (in MWh)
While the exact phrase "solution reliability evaluation of engineering systems by Roy Billinton and" points toward his foundational textbook "Reliability Evaluation of Engineering Systems: Concepts and Techniques" (co-authored with Ronald N. Allan), the core methodology is universally known as . | | Customer | CAIDI | Customer Average