Composite system reliability analysis using an accelerated state evaluation considering bus load correlation

This paper presents an accelerated state evaluation (ASE) in sequential simulation for composite system reliability analysis, with the consideration of bus load correlation. The ASE computes a threshold load level at each sampled component state and uses it to identify load-loss states efficiently. As such, the number of load curtailment computations involving optimal power flow can be greatly reduced to achieve higher simulation efficiency. The ASE is developed for systems with and without correlated bus loads. Case studies are performed to demonstrate its performances, where reliability indices - loss of load probability, expected unserved energy, loss of load frequency and duration are obtained. Results on IEEE Reliability Test System (IEEE RTS) show that compared to conventional approach, ASE leads to considerably higher computing efficiency while achieving solutions of similar quality. It is also found from an extreme case that if system loads exhibit independency, the applicability of ASE might be restricted for some intensively stressed systems.