Network planning evaluation implementing time varying thermal ratings

Contemporary transmission networks are not fully utilized due to increased uncertainty and security buffers resulting mainly from the inefficient operation and planning, currently based on conservative predetermined thermal ratings. However, in a smart operation scheme, which considers time varying thermal ratings of transmission assets, operation and planning could be optimized to facilitate the proliferation of generation expansion projects while maintaining required levels of reliability. This paper presents a methodology which enhances the current methods of network element ratings by incorporating a more detailed modelling of the overhead line (OHL) properties. Three thermal rating models, static (STR), seasonal (SeTR) and time varying (TVTR), are implemented for comparative studies, under both deterministic and probabilistic frameworks with an aim to identify the most cost-effective and optimal flexible network operation plan in today´s congestion-driven and competitive power markets. In addition, the effects of line outages on transmission losses in the electric power networks are presented, quantifying the transmission losses in a realistic manner due to the incorporation of real thermal ratings. The IEEE 24-bus RTS is used under sequential modeling to validate the methodological enhancements and to evaluate network performance. The system annual operating costs are reduced when using the proposed TVTR model.