Research On Calculation Method And Monitoring Device Of Carrying Capacity Of Large-span Overhead Power Transmission Lines

With the continuous development of national economy,the rapidly increasing demand for electric power has put forward higher requirements for the operation and dispatching ability of electric power in China.However,due to the constraints of economy and space,especially the increasing awareness of environmental protection,it is difficult to set up a new transmission line and meet the soaring demand for electricity.From the perspective of the actual transmission situation of the power grid,the weather conditions are generally better than the assumed worst weather conditions in the calculation of the conductor carrying capacity in the technical code for the design of overhead power transmission lines in China most of the time,which makes it possible to appropriately improve the transmission capacity of existing lines in the short term.It is of great practical significance to study how to improve the utilization rate of existing large-span transmission lines' invisible transmission capacity while meeting the safety requirements.In this paper,the relationship between equivalent wind speed and wire temperature and other factors,such as wire temperature,ambient temperature,sunshine intensity,wind speed and wind direction,was studied through MATLAB simulation.Combined with Dynamic Line Rating(DLR),the boundary conditions of large span transmission lines are studied.The concept of equivalent wind speed is proposed to solve the problem that it is difficult to determine the value of wind speed in dynamic capacity increase.Secondly,the research and development of transmission line real-time monitoring device is introduced.On this basis,through the statistical analysis of the equivalent wind speed data collected by the monitoring device,the distribution law of the equivalent wind speed is found.Taking the typical line(Gufeng line a and Yanxi line b)as an example,the recommended value of the current-carrying capacity for calculating the equivalent wind speed is obtained by means of statistics and probability.