This paper discusses the impact of dynamic line rating (henceforth DLR) of transmission lines on power flow of the Colombian National Interconnected System (SIN, in Spanish), specifically in the Department of Cundinamarca. Input data were meteorological values as angle of wind, wind speed and environmental temperature. DLR was implemented on National Laboratory of Smart Grids, LAB-i, on Bogotá Campus of Universidad Nacional de Colombia to find dynamic rating, resistance, capacitance and inductance in transmission lines of Cundinamarca. LAB-i platform was used to visualize the results of lines and power flow model, which was ran hourly for 1 day. In addition, voltage and power factor at system nodes are shown. The results indicate that transmission lines can carry 70.9% more current using DLR regarding static rating and DLR improved power systems calculations. Active energy losses decreased 39.27% during a day compared to a power flow when line rating is static. Efficiency of the line is directly related to its rating, i.e. the efficiency of lines is higher at nights, when the peak occurs in the daily load curve in Colombia. Dynamic rating is inversely related to voltage magnitude at a PV node and directly related to the voltage at a PQ node. This is due to variations in the voltage drop of the line. Voltages do not exceed the ranges established by the local and international regulations and their variation was up to 0.02% at PV nodes and 0.04% at PQ nodes for one day.