A Joint Deterministic - Probabilistic Approach To Bulk System Reliability Assessment

Most electric power utilities utilize probability methods in the planning and operation of generating capacity. Deterministic criteria, however, are usually used in the planning and operation of composite generation and transmission or bulk electric power systems. The most commonly applied deterministic criteria dictate that specific credible outages should not result in system failure. The traditional deterministic criterion used in bulk electric systems is known as the N-l security criterion, under which, the loss of any single BES component will not result in system failure. Deterministic techniques do not include an assessment of the actual system reliability and are inconsistent as they do not incorporate the probabilistic or stochastic nature of system behaviour and component failures. This paper introduces and illustrates the application of a joint deterministic-probabilistic (D-P) criterion for bulk electric system planning that can be applied using any software package developed and accepted for probabilistic assessment. The D-P concept is a deterministic framework that incorporates a probabilistic criterion. The paper illustrates the application of the conventional deterministic N-l, the basic probabilistic (P) and the D-P criteria to a published test system.