Research On Dynamic Carrying Capacity Evaluation And Application Method Of Transmission Line

With the development of science and technology,the enhancement of People’s awareness of environmental protection,the lack of fossil energy,and the limitation of thermal power generation,the malpractice gradually emerged,requiring a large amount of new energy to be incorporated into transmission lines,with the strong support of the state,more and more clean energy is being integrated into the power grid,and according to the approval of the Jilin Provincial Development and Reform Commission,new energy capacity will be added later,which will have an increasing impact on power transmission lines.According to the distribution of transmission lines in China,3.59% of the transmission lines are laid with voltage grade 110 k V or above,and 78.94% of the transmission lines are laid with voltage grade 10 k V or above,statistics show that more than 86% of the 10 k V lines in Jilin province use LGJ type cables,and 81% of the 10 k V cables in operation have a life cycle of less than 15 years,due to the incompleteness of the factors considered,so a lot of waste of resources.Therefore,in-depth study and analysis of transmission lines under a variety of factors under the characteristics and mechanisms of the transmission lines to evaluate the dynamic load-carrying capacity of the transmission lines,for enhancing the power grid transmission capacity and stability of the ability to play an important role.First of all,it analyzes the material and composition of power cable,analyzes the use,advantages and disadvantages of each material and applicable scenarios,etc.,this paper summarizes the influence of laying environment and laying mode on the current carrying capacity of power cable,and obtains the advantages of establishing the dynamic mathematical model of current carrying capacity by using the method of heat transfer,in this paper,the dynamic parameters of transmission line in trench and overhead laying are analyzed,and the calculation formula of dynamic current carrying capacity is summarized through the energy conservation of heat transfer,the temperature rise formula of power cable is provided.Secondly,the dynamic current carrying capacity of transmission line is analyzed and calculated systematically in a certain place in Jilin province.The dynamic current carrying capacity between two substations is analyzed in a power grid system in Jilin province,that is,the dynamic parameters based on terminal electrical and meteorological information are introduced into the heat transfer method,and the dynamic current carrying capacity is obtained,the feasibility of the calculation method is confirmed by comparing with the actual current carrying capacity measured in the station before,and the current carrying capacity of the power grid under the condition of “1 + N” is analyzed,it provides a theoretical basis for the transmission capacity of the local power grid.Finally,by developing a module in the dispatching system,combining the existing substation inland CT,PT and other parameters and transmission line fixed parameters,integration of commonly used laying mode,cross-section,material and other information,programming through VB6.0,using the current-carrying formula in Chapter 3,it is possible to calculate the outlet current carrying capacity of multiple lines quickly and accurately.The corresponding fast calculation method of current carrying capacity is designed in OMS.