A PROBABILISTIC TECHNIQUE FOR OPERATING RESERVE ASSESSMENT USING SYSTEM OPERATING STATES

Abstract

Operating reserve assessment in an electric power system is normally performed using deterministic criteria. Deterministic approaches do not include an assessment of the actual system reliability as they do not take into account the probabilistic or stochastic nature of system behavior and component failures. Probabilistic techniques, however, respond to the significant factors which affect the reliability of a system. Deterministic criteria are, however, easier for the system operator to understand, than a risk index determined using probabilistic techniques. In order to alleviate the difficulty in interpreting the risk index and provide more applicable information for the system operator, deterministic considerations can be included in the probabilistic assessment. A probabilistic technique is illustrated in this thesis to assess the operating reserve requirements in a system. This technique combines deterministic criteria with probabilistic indices to monitor the system wellbeing. In this approach, the generation system is classified into different system operating states. A risk index designated as the Generating System Operating State Risk (GSOSR) is defined in this thesis as the probability of residing in an undesirable operating state. The technique together with the effect on the GSOSR and the system operating state probabilities of factors such as lead time, system peak load, load forecast uncertainty and generating unit derated states are illustrated in this thesis. The inclusion of rapid start and hot reserve units and interruptible loads in the analysis can affect the GSOSR and the system operating state probabilities. The effects of these factors have been incorporated in the operating reserve assessment using the concept of area risk curves. The effect of various degrees of postponability on the GSOSR and the system operating state probabilities are also discussed. Two reliability test systems, the RBTS and the IEEE-RTS, have been utilized in the wide range of studies presented in this thesis.