Fuzzy Dynamic Thermal Rating of Transmission Lines

Dynamic thermal rating (DTR) of transmission system facilities is a way to maximally realize the equipment capacities while not threatening their health. With regards to transmission lines, the allowable current of conductors is forecasted based on the environmental situations expected in some forthcoming time periods. Due to the fact that weather conditions continuously vary, sampling points are very limited against many line spans, and the measurements have an inherent error, uncertainties must be appropriately included in the DTR determination. This paper adopts the fuzzy theory as a strong and simple tool to model uncertainties in the DTR calculation. Since DTR intends to determine the line capacity for some periods ahead, the capability of fuzzy computation in predicting future phenomena is very fruitful here. In the proposed model, variables, such as ambient temperature, wind speed, wind direction, and solar hour angle are assumed to be fuzzy numbers. Numerical simulations are provided based on inputs taken from real databases and reasonable assumptions as well. The results obtained support the validation and efficiency of the proposed model.