Solution Reliability Evaluation Of Engineering Systems By Roy Billinton And May 2026

For a power system with total generation capacity C and load L (which varies over time), LOLP = Probability (C < L).

But they went further. They developed the in days/year, and the Expected Energy Not Supplied (EENS) in MWh/year. These indices became regulatory standards. For a power system with total generation capacity

, a University of Saskatchewan professor, is often called the "father of power system reliability." He founded the Power Systems Research Group and spent 50 years embedding probabilistic risk assessment into an industry historically dominated by deterministic rules (e.g., "always keep one extra generator running"). These indices became regulatory standards

Before Billinton and Allan, reliability was often an afterthought: a firefighting exercise conducted after a blackout or a structural collapse. After their work, reliability became a predictive science—a mathematical discipline that could be solved, optimized, and banked on. After their work

, of UMIST (University of Manchester Institute of Science and Technology), brought a European rigor to system modeling, particularly in distribution and composite systems.