Generating unit commitment in composite generation and transmission systems

A composite generation and transmission system can be divided into various states which can be used to indicate the degree to which adequacy and security constraints are satisfied when conducting a system reliability assessment. A new risk index designated as the composite system operating state risk (CSOSR) is defined, using the probabilities of these operating states. This risk index can be utilised for system expansion planning and unit commitment in a composite system. The application of this risk index for unit commitment in a composite system is presented using two test systems. The results for different generating unit lead times for a fixed load level and for variable load levels for a fixed lead time are also presented